diff --git a/newLang/cfg/compiler.cfg b/newLang/cfg/compiler.cfg
index 5489761..b573252 100644
--- a/newLang/cfg/compiler.cfg
+++ b/newLang/cfg/compiler.cfg
@@ -4,8 +4,9 @@
 #
 # Bank 0 (CR=$0E)                      Bank 1 (CR=$4E)
 #   $0000-$12FF system (BASIC/KERNAL)    $0000-$1FFF hidden by common RAM
-#   $1300-$18FF COMMON (copied at init)  $2000-$BFFF BANK1 compiler tables
-#   $1900-$19FF DISKBUF                  $C000-$FFFF system ROM (unmapped RAM)
+#   $1300-$18FF COMMON (copied at init)  $2000-$6AFF SRCCACHE source cache
+#   $1900-$19FF DISKBUF                  $6B00-$BFFF BANK1 compiler tables
+#                                        $C000-$FFFF system ROM (unmapped RAM)
 #   $1A00-$1AFF private zero page (P0)
 #   $1B00-$1BEF SCRATCH (common)
 #   $1BF0-$1BFF MAILBOX
@@ -28,7 +29,9 @@ MEMORY {
     MAILBOX:   file = "", start = $1BF0, size = $0010, define = yes;
     SWSTACK:   file = "", start = $B800, size = $0800, define = yes;   # to $BFFF
 
-    BANK1:     file = "", start = $2000, size = $A000, define = yes;   # to $BFFF
+    # Whole-file source cache (D118): >= 18,999 bytes, page aligned.
+    SRCCACHE:  file = "", start = $2000, size = $4B00, define = yes;   # to $6AFF
+    BANK1:     file = "", start = $6B00, size = $5500, define = yes;   # to $BFFF
 }
 
 SEGMENTS {
@@ -45,6 +48,7 @@ SEGMENTS {
     SCRATCH:   load = SCRATCH,   type = bss, optional = yes;
     MAILBOX:   load = MAILBOX,   type = bss, optional = yes;
     SWSTACK:   load = SWSTACK,   type = bss, optional = yes;
+    SOURCE:    load = SRCCACHE,  type = bss, optional = yes, define = yes;
     TABLES:    load = BANK1,     type = bss, optional = yes, define = yes;
 }
 
diff --git a/newLang/docs/architecture.md b/newLang/docs/architecture.md
index e1a04d0..f00a3e8 100644
--- a/newLang/docs/architecture.md
+++ b/newLang/docs/architecture.md
@@ -141,7 +141,8 @@ and `docs/memory-map.md` explains it and gives the evidence. In summary:
 - **Bank 0:** COMMON `$1300-$18FF` (copied at init), DISKBUF `$1900`, private
   zero page `$1A00`, SCRATCH `$1B00-$1BEF`, MAILBOX `$1BF0-$1BFF`, MAIN
   `$1C0D-$B7FF` (STARTUP first), SWSTACK `$B800-$BFFF`.
-- **Bank 1:** compiler tables `$2000-$BFFF` (40 KB).
+- **Bank 1:** source cache `$2000-$6AFF` (D118), compiler tables
+  `$6B00-$BFFF` (21,760 bytes).
 - **Zero page:** the compiler owns logical `$02-$FF` via P0; KERNAL calls run
   on the system zero page.
 - **NMI:** guarded by `mmu_nmi_guard` through `$0318`; RESTORE is ignored
@@ -195,8 +196,10 @@ pointer-rich abstract syntax tree.
 - write PRG and MAP output;
 - delete or invalidate partial output on failure.
 
-Repeated passes trade disk/source traversal time for bounded memory. The source
-stream should be rewindable without reopening unsafe shared emulator state.
+Repeated passes re-read the source, not the disk. `src_load` (`source.s`)
+reads the file once into the bank-1 cache and enforces the editor-profile
+limits. Each pass calls `src_rewind`, then `src_next_line` delivers one logical
+line at a time into a common-RAM buffer (D118, E02-S01).
 
 ## 6. Compiler Data Records
 
@@ -386,6 +389,5 @@ features depend on it.
 - Generated-program memory map (the compiler map is frozen in section 4.4)
 - Final interface-result convention
 - Compiler table capacities and their user-visible resource limits
-- Whether to cache the complete source in banked RAM when it fits
 - Physical-hardware acceptance requirements
 
diff --git a/newLang/docs/decisions.md b/newLang/docs/decisions.md
index 2e9e06b..191cae6 100644
--- a/newLang/docs/decisions.md
+++ b/newLang/docs/decisions.md
@@ -39,6 +39,7 @@ documented default. `Proposed` means a later change still needs approval.
 | D115 | Character literals use single quotes and contain exactly one PETSCII character or supported escape. | The `char` type has a direct, unambiguous literal form while `//` remains the comment syntax. |
 | D116 | Runtime faults report a stable code and the best available map-resolvable program address. | Rich stack traces are deferred; faults remain diagnosable within the runtime budget. |
 | D117 | Freeze the compiler memory map in `cfg/compiler.cfg`: 8K bottom common RAM, COMMON at `$1300`, private zero page at bank 0 page `$1A` via P0, bank-1 tables at `$2000-$BFFF`, IRQs masked and NMIs guarded in compiler states, test mailbox at `$1BF0`. | Internal contract backed by E01-S05 x128 evidence (`docs/memory-map.md`); no user-visible behavior except that RESTORE is ignored while compiling. Generated-program maps remain open. |
+| D118 | The compiler loads the whole source file once into a bank-1 cache (`$2000-$6AFF`) and replays it for every pass, instead of re-reading the disk. | Rewind is exact by construction and avoids reading a slow disk three times. Compiler tables get the remaining 21,760 bytes of bank 1 (`$6B00-$BFFF`). Internal; no user-visible behavior. |
 
 ## Proposed
 
@@ -61,6 +62,6 @@ No proposed product changes are currently pending.
 
 1. What generated-program memory map should E04-S01/E04-S02 adopt? (The
    compiler map is D117.)
-2. What compiler table capacities fit in the 40 KB bank-1 window and 254-byte
-   zero page now that the compiler map is frozen?
+2. What compiler table capacities fit in the 21,760-byte bank-1 table window
+   and 254-byte zero page (D117, D118)?
 
diff --git a/newLang/docs/memory-map.md b/newLang/docs/memory-map.md
index eefc8b8..e20d3e5 100644
--- a/newLang/docs/memory-map.md
+++ b/newLang/docs/memory-map.md
@@ -1,7 +1,8 @@
 # Nova128 Compiler Memory Map
 
 Story: E01-S05  
-Status: frozen for the compiler (D117); verified in VICE x128 3.10  
+Status: frozen for the compiler (D117, source cache D118); verified in VICE
+x128 3.10  
 Authoritative source: `cfg/compiler.cfg`. This document explains it.
 
 The generated-program memory map is **not** frozen here. It belongs to E04-S01
@@ -42,12 +43,13 @@ COMMON, DISKBUF, private ZP, SCRATCH, and MAILBOX are visible from bank 1.
 | Range | Size | Name | Contents |
 |---|---|---|---|
 | `$0000-$1FFF` | | hidden | Covered by bottom common RAM in compiler states |
-| `$2000-$BFFF` | 40960 | BANK1 / `TABLES` | Names, symbols, class/interface/type records, pass workspaces |
+| `$2000-$6AFF` | 19200 | SRCCACHE / `SOURCE` | Whole source file, loaded once by `src_load` (18,999-byte limit) |
+| `$6B00-$BFFF` | 21760 | BANK1 / `TABLES` | Names, symbols, class/interface/type records, pass workspaces |
 | `$C000-$FFFF` | | unmapped | System ROM is visible here instead; BASIC string space at the top of bank 1 is untouched |
 
 Bank-1 data is reached only through `mmu.s` helpers (`mmu_peek1`/`mmu_poke1`
-with the zero-page pointer `mmu_ptr`, and later block-copy routines), or by
-code in COMMON. MAIN code never runs while bank 1 is mapped, because MAIN above
+and `mmu_copy_to1`, using the zero-page pointers `mmu_ptr`/`mmu_src`), or by
+code in COMMON such as `src_fetch_line`. MAIN code never runs while bank 1 is mapped, because MAIN above
 `$1FFF` is not visible then.
 
 BASIC 7 keeps variables in bank 1 from `$0400`. The compiler is started with
@@ -59,7 +61,7 @@ state.
 In compiler states P0 points at bank 0 page `$1A`, so the compiler owns the
 whole logical zero page `$02-$FF` (linker area `ZP`, 254 bytes). `$00/$01` are
 the 8502 port and are never allocated. Modules allocate zero page only through
-the `ZEROPAGE` segment. Current users: `mmu_ptr` (2 bytes).
+the `ZEROPAGE` segment. Current users: `mmu_ptr` and `mmu_src` (4 bytes).
 
 System zero page stays intact. KERNAL calls switch P0 back to `$0000` for the
 call. While P0 is relocated, the system zero page is still readable at
@@ -117,7 +119,7 @@ Protocol:
 |---|---|
 | ZP | A store to logical ZP lands at `$1Axx`; system ZP is unchanged |
 | KCALL | CHROUT via `kcall_inline` from both states; private ZP and CR/P0 intact afterwards |
-| BANK1 | First and last TABLES bytes hold bank-1 values; bank 0 at the same addresses unchanged |
+| BANK1 | First and last TABLES bytes (`$6B00`, `$BFFF`) hold bank-1 values; bank 0 at the same addresses unchanged |
 | COMMON | DISKBUF/SCRATCH written in bank 0 read back in bank 1; mailbox written from bank 1 |
 | NMI | A CIA #2 timer NMI taken in the bank-1 state returns with CR `$4E`, P0 `$1A`, sentinel `$C5`, and the same SP |
 | RESTORE | After `mmu_shutdown`: CR/RCR/P0/P1/`$0318` and SP equal their entry values |
diff --git a/newLang/planning/claims/E02-S01.md b/newLang/planning/claims/E02-S01.md
new file mode 100644
index 0000000..6e5448d
--- /dev/null
+++ b/newLang/planning/claims/E02-S01.md
@@ -0,0 +1,90 @@
+---
+story: E02-S01
+owner: e02_source_reader
+status: done
+started: 2026-11-07
+depends-on: [E01-S03, E01-S05]
+---
+
+# E02-S01 Claim
+
+## Intended change
+
+Add the compiler's source reader. `src_load` reads a PETSCII SEQ file from
+device 8 once into a bank-1 cache, enforcing the line, line-count, and file
+size limits with stable error codes and exact positions. `src_rewind` and
+`src_next_line` then replay the cached source identically for every pass,
+one logical line at a time. Disk access goes through new `diskio.s` KERNAL
+wrappers that always close their channels.
+
+## File area
+
+- `src/compiler/source.s`, `src/compiler/diskio.s`
+- `src/common/source.inc`
+- `src/compiler/mmu.s` (bank-1 block copy only)
+- `cfg/compiler.cfg` (bank-1 source cache area)
+- `tests/platform/map-skeleton.s` (table-size constant only)
+- `tests/source/`
+- `scripts/build-source-test.ps1`, `scripts/verify-source-test.ps1`,
+  `scripts/lib/`
+- `docs/memory-map.md`, `docs/architecture.md`, `docs/decisions.md` (D118)
+- `planning/claims/E02-S01.md`
+- generated files under `build/`
+
+## Acceptance evidence
+
+- [x] Reads Vim-created SEQ source without host conversion: fixtures use
+  Vim's exact save format (PETSCII, `$0D` lines, both letter ranges in
+  `decls.n8`); the reader delivers the bytes unchanged, verified by a host
+  Fletcher-16 match. A live Vim edit is E07-S03.
+- [x] Accepts `$0D` lines and a missing final `$0D`: `nofinal.n8` yields the
+  same 50 lines and checksum as `decls.n8` with one byte fewer.
+- [x] Enforces line/file limits with stable errors: `edge.n8` (80-byte line,
+  599 lines, 18,999 bytes) loads; `longln.n8` -> code 3 at 3:81,
+  `manyln.n8` -> code 4 at 600:1, `big.n8` -> code 2 at 500:38.
+- [x] Rewinds identically for all compiler passes: two replays per load give
+  identical line counts and checksums, and `src_line_no` ends at the line
+  count.
+- [x] Disk failure closes channels and leaves no partial output: `LDTND` is 0
+  after every load; after each failure `src_len` is 0 and `src_next_line`
+  returns end of source at once; a later `decls.n8` load succeeds unchanged.
+
+## Coordination notes
+
+Source error codes are reader return codes. E02-S04 maps them to stable `Exxx`
+diagnostics. A true Vim round trip (edit in x64sc, compile in x128) is
+E07-S03; this story proves the reader consumes Vim's exact byte format
+(`../vim/NOTES.md`, `vedit.c` save path) with no conversion.
+
+## Work log
+
+- Confirmed Vim's save format in `../vim/NOTES.md` and `vedit.c` (raw
+  buffer, `$0D` lines, final `$0D` appended, 80-column wrap on load).
+- Recorded D118: one disk read into a bank-1 cache (`$2000-$6AFF`), tables
+  keep `$6B00-$BFFF` (21,760 bytes). Map skeleton re-verified with it.
+- Added `mmu_copy_to1` and `mmu_src` to `mmu.s`, `diskio.s` with a COMMON
+  chunk reader run through `kcall`, `source.s`, and `diskio.inc`.
+- Added `scripts/lib/Nova128Test.psm1` (link, PETSCII conversion, disk
+  images, remote monitor, mailbox polling). The monitor helper waits for the
+  `(C:$xxxx)` prompt; a fixed delay returned empty replies with a 1581.
+- Negative control: allowing 81-byte lines makes the C128 report FAIL and the
+  host flag `longln.n8` (code 0, position 0:0, 100 bytes kept). Restored.
+
+## Completion
+
+- Tests run: `scripts/verify-source-test.ps1` (pass plus mutation run),
+  `scripts/verify-map-skeleton.ps1`, `scripts/verify-kernal-probe.ps1`,
+  `tests/grammar/validate.ps1`, `tests/disk/prepare-disk.tests.ps1`.
+- Results: all 8 fixture records match host expectations; screenshot shows
+  each result code and `NOVA128 SOURCE TEST OK`; regressions pass.
+- Files changed: `src/compiler/source.s`, `src/compiler/diskio.s`,
+  `src/compiler/mmu.s`, `src/common/source.inc`, `src/common/diskio.inc`,
+  `cfg/compiler.cfg`, `tests/source/source-test.s`,
+  `tests/platform/map-skeleton.s`, `scripts/build-source-test.ps1`,
+  `scripts/verify-source-test.ps1`, `scripts/build-map-skeleton.ps1`,
+  `scripts/lib/Nova128Test.psm1`, `docs/memory-map.md`,
+  `docs/architecture.md`, `docs/decisions.md` (D118), this claim.
+- Remaining risks: device 8 is fixed; a read error part-way through a file
+  (ST error other than EOI) is handled in code but not exercised, since VICE
+  offers no simple way to inject one; only the 1581 (D81) was tested; error
+  codes are reader codes until E02-S04 assigns user-facing `Exxx` IDs.
diff --git a/newLang/scripts/build-map-skeleton.ps1 b/newLang/scripts/build-map-skeleton.ps1
index 62a2456..aad1856 100644
--- a/newLang/scripts/build-map-skeleton.ps1
+++ b/newLang/scripts/build-map-skeleton.ps1
@@ -87,7 +87,7 @@ if ($labelText -notmatch "(?im)^al\s+001C0D\s+\.skel_entry\s*$") {
     throw "skel_entry is not at `$1C0D (the SYS 7181 target)"
 }
 Require-Segment "SWSTACK" 0xB800 0xBFFF
-Require-Segment "TABLES" 0x2000 0xBFFF
+Require-Segment "TABLES" 0x6B00 0xBFFF
 if ($segments["MAILBOX"].Start -ne 0x1BF0) { throw "mailbox is not at `$1BF0" }
 
 $bytes = [IO.File]::ReadAllBytes($program)
@@ -95,7 +95,7 @@ if ($bytes[0] -ne 0x01 -or $bytes[1] -ne 0x1C) { throw "load address is not `$1C
 
 Write-Host ("built {0} ({1} bytes)" -f $program, $bytes.Length)
 $limits = [ordered]@{
-    ZEROPAGE = 0x00FE; COMMON = 0x0600; SWSTACK = 0x0800; TABLES = 0xA000
+    ZEROPAGE = 0x00FE; COMMON = 0x0600; SWSTACK = 0x0800; TABLES = 0x5500
 }
 foreach ($name in ($segments.Keys | Sort-Object { $segments[$_].Start })) {
     $seg = $segments[$name]
diff --git a/newLang/scripts/build-source-test.ps1 b/newLang/scripts/build-source-test.ps1
new file mode 100644
index 0000000..041eae4
--- /dev/null
+++ b/newLang/scripts/build-source-test.ps1
@@ -0,0 +1,117 @@
+# E02-S01: build the source-reader test PRG and a fresh D81 holding it plus
+# generated PETSCII fixtures. Writes build/source-test/expected.json with the
+# results the host computes independently of the C128 code.
+[CmdletBinding()]
+param()
+
+$ErrorActionPreference = "Stop"
+$project = Split-Path $PSScriptRoot -Parent
+Import-Module (Join-Path $PSScriptRoot "lib\Nova128Test.psm1") -Force
+$out = Join-Path $project "build\source-test"
+New-Item -ItemType Directory -Force -Path $out | Out-Null
+
+$link = Invoke-Nova128Link -Name "source-test" -BuildDir $out `
+    -Config (Join-Path $project "cfg\compiler.cfg") -Sources @(
+        (Join-Path $project "src\compiler\mmu.s"),
+        (Join-Path $project "src\compiler\diskio.s"),
+        (Join-Path $project "src\compiler\source.s"),
+        (Join-Path $project "tests\source\source-test.s"))
+if ((Get-Nova128Label $link.Labels "test_entry") -ne 0x1C0D) { throw "test_entry is not at `$1C0D" }
+
+# ---------------------------------------------------------------- fixtures
+function Get-Lines([byte[]]$bytes) {
+    # Split exactly as src_next_line does: $0D ends a line; trailing bytes
+    # without $0D form a last line.
+    $lines = New-Object System.Collections.Generic.List[byte[]]
+    $start = 0
+    for ($i = 0; $i -lt $bytes.Length; $i++) {
+        if ($bytes[$i] -eq 13) {
+            if ($i -gt $start) { $lines.Add([byte[]]$bytes[$start..($i - 1)]) }
+            else { $lines.Add([byte[]]@()) }
+            $start = $i + 1
+        }
+    }
+    if ($start -lt $bytes.Length) { $lines.Add([byte[]]$bytes[$start..($bytes.Length - 1)]) }
+    return ,$lines
+}
+
+function Get-Fletcher([byte[]]$bytes) {
+    $s1 = 0; $s2 = 0
+    foreach ($line in (Get-Lines $bytes)) {
+        foreach ($b in (@($line) + 13)) {
+            $s1 = ($s1 + $b) % 255
+            $s2 = ($s2 + $s1) % 255
+        }
+    }
+    return @($s1, $s2)
+}
+
+function New-Line([int]$length, [int]$seed) {
+    # Mixed case so both PETSCII letter ranges appear.
+    $alphabet = "abcdefghijKLMNOPQRST0123456789 =+()"
+    $chars = for ($i = 0; $i -lt $length; $i++) { $alphabet[($i + $seed) % $alphabet.Length] }
+    return (-join $chars)
+}
+
+$fixtures = [ordered]@{}
+$decls = ConvertTo-Nova128Petscii (Get-Content -Raw (Join-Path $project "tests\grammar\accepted\decls.n8"))
+if ($decls[-1] -ne 13) { throw "decls.n8 should end with a newline" }
+$fixtures["decls.n8"] = $decls
+$fixtures["nofinal.n8"] = [byte[]]$decls[0..($decls.Length - 2)]
+
+$edge = New-Object System.Text.StringBuilder
+[void]$edge.Append((New-Line 80 0) + "`n")              # exactly the line limit
+for ($i = 0; $i -lt 598; $i++) {
+    $len = if ($i -lt 380) { 31 } else { 30 }        # totals exactly 18,999 bytes
+    [void]$edge.Append((New-Line $len $i) + "`n")
+}
+$fixtures["edge.n8"] = ConvertTo-Nova128Petscii $edge.ToString()
+
+$long = "a = 1`nb = 2`n" + (New-Line 81 3) + "`nc = 3`n"
+$fixtures["longln.n8"] = ConvertTo-Nova128Petscii $long
+
+$many = (1..600 | ForEach-Object { "x = $_" }) -join "`n"
+$fixtures["manyln.n8"] = ConvertTo-Nova128Petscii ($many + "`n")
+
+$big = (1..500 | ForEach-Object { New-Line 37 $_ }) -join "`n"
+$fixtures["big.n8"] = ConvertTo-Nova128Petscii ($big + "`n")
+
+# Boundary sanity: these are the facts the expectations below rely on.
+$edgeLines = Get-Lines $fixtures["edge.n8"]
+if ($fixtures["edge.n8"].Length -ne 18999 -or $edgeLines.Count -ne 599 -or $edgeLines[0].Length -ne 80) {
+    throw "edge.n8 is not at the exact limits"
+}
+if ($fixtures["big.n8"].Length -ne 19000) { throw "big.n8 is not 19,000 bytes" }
+$hasLow = $decls | Where-Object { $_ -ge 0x41 -and $_ -le 0x5A }
+$hasHigh = $decls | Where-Object { $_ -ge 0xC1 -and $_ -le 0xDA }
+if (-not $hasLow -or -not $hasHigh) { throw "decls.n8 lacks one PETSCII letter range" }
+
+$files = @(@{ Name = "source-test"; Path = $link.Program; Type = "prg" })
+foreach ($name in $fixtures.Keys) {
+    $path = Join-Path $out ($name -replace '\.n8$', '.pet')
+    [IO.File]::WriteAllBytes($path, $fixtures[$name])
+    $files += @{ Name = $name; Path = $path; Type = "seq" }
+}
+$disk = Join-Path $out "source-test.d81"
+New-Nova128Disk -Path $disk -Files $files
+
+# ------------------------------------------------------------ expectations
+function Ok([string]$name) {
+    $b = $fixtures[$name]; $f = Get-Fletcher $b
+    return [ordered]@{ name = $name; code = 0; lines = (Get-Lines $b).Count; len = $b.Length;
+        s1 = $f[0]; s2 = $f[1] }
+}
+$expected = @(
+    (Ok "decls.n8"),
+    (Ok "nofinal.n8"),
+    (Ok "edge.n8"),
+    [ordered]@{ name = "longln.n8"; code = 3; line = 3; col = 81 },
+    [ordered]@{ name = "manyln.n8"; code = 4; line = 600; col = 1 },
+    [ordered]@{ name = "big.n8"; code = 2; line = 500; col = 38 },
+    [ordered]@{ name = "missing.n8"; code = 1; dos = 62 },
+    (Ok "decls.n8")
+)
+$expected | ConvertTo-Json -Depth 4 | Set-Content -LiteralPath (Join-Path $out "expected.json")
+
+Write-Host ("built {0}" -f $link.Program)
+Write-Host ("disk  {0} ({1} fixtures)" -f $disk, $fixtures.Count)
diff --git a/newLang/scripts/lib/Nova128Test.psm1 b/newLang/scripts/lib/Nova128Test.psm1
new file mode 100644
index 0000000..ed84765
--- /dev/null
+++ b/newLang/scripts/lib/Nova128Test.psm1
@@ -0,0 +1,233 @@
+# Shared helpers for Nova128 build and x128 verification scripts.
+#   Import-Module (Join-Path $PSScriptRoot "lib\Nova128Test.psm1") -Force
+
+$script:ViceBin = "C:\Program Files\GTK3VICE-3.10-win64\bin"
+
+function Get-ViceTool([string]$Name) {
+    $path = Join-Path $script:ViceBin "$Name.exe"
+    if (-not (Test-Path -LiteralPath $path)) { throw "$Name.exe not found at $path" }
+    return $path
+}
+
+# Assemble each source and link them with an ld65 config.
+# Returns @{ Program; Map; Labels }.
+function Invoke-Nova128Link {
+    param(
+        [Parameter(Mandatory)][string]$Name,
+        [Parameter(Mandatory)][string[]]$Sources,
+        [Parameter(Mandatory)][string]$Config,
+        [Parameter(Mandatory)][string]$BuildDir,
+        [string[]]$Defines = @()
+    )
+    $ca65 = (Get-Command ca65 -ErrorAction Stop).Source
+    $ld65 = (Get-Command ld65 -ErrorAction Stop).Source
+    New-Item -ItemType Directory -Force -Path $BuildDir | Out-Null
+    $out = @{
+        Program = Join-Path $BuildDir "$Name.prg"
+        Map = Join-Path $BuildDir "$Name.map"
+        Labels = Join-Path $BuildDir "$Name.lbl"
+    }
+    foreach ($path in $out.Values) {
+        if (Test-Path -LiteralPath $path) { Remove-Item -LiteralPath $path -Force }
+    }
+    $defineArgs = @()
+    foreach ($d in $Defines) { $defineArgs += @("-D", $d) }
+    $objects = @()
+    foreach ($source in $Sources) {
+        $object = Join-Path $BuildDir ("$Name-" + [IO.Path]::GetFileNameWithoutExtension($source) + ".o")
+        & $ca65 --cpu 6502 @defineArgs -o $object $source
+        if ($LASTEXITCODE -ne 0) { throw "ca65 failed on $source" }
+        $objects += $object
+    }
+    $linkOutput = & $ld65 -C $Config -o $out.Program -m $out.Map -Ln $out.Labels @objects 2>&1
+    if ($LASTEXITCODE -ne 0) { throw ("ld65 failed:`n" + ($linkOutput | Out-String)) }
+    return $out
+}
+
+function Get-Nova128Label {
+    param([Parameter(Mandatory)][string]$Labels, [Parameter(Mandatory)][string]$Name)
+    $text = Get-Content -Raw -LiteralPath $Labels
+    $m = [regex]::Match($text, "(?im)^al\s+([0-9a-f]+)\s+\." + [regex]::Escape($Name) + "\s*$")
+    if (-not $m.Success) { throw "label $Name not found in $Labels" }
+    return [Convert]::ToInt32($m.Groups[1].Value, 16)
+}
+
+# ASCII text -> PETSCII SEQ bytes, using the same rules as Vim and
+# prepare-disk.ps1: a-z -> $41-$5A, A-Z -> $C1-$DA, CRLF/LF -> $0D.
+function ConvertTo-Nova128Petscii {
+    param([Parameter(Mandatory)][AllowEmptyString()][string]$Text)
+    $bytes = [Text.Encoding]::ASCII.GetBytes($Text)
+    $out = New-Object System.Collections.Generic.List[byte]
+    for ($i = 0; $i -lt $bytes.Length; $i++) {
+        $v = $bytes[$i]
+        if ($v -eq 13) {
+            if ($i + 1 -lt $bytes.Length -and $bytes[$i + 1] -eq 10) { continue }
+            $out.Add(13); continue
+        }
+        if ($v -eq 10) { $out.Add(13); continue }
+        if ($v -ge 0x61 -and $v -le 0x7A) { $out.Add([byte]($v - 0x20)); continue }
+        if ($v -ge 0x41 -and $v -le 0x5A) { $out.Add([byte]($v + 0x80)); continue }
+        $out.Add($v)
+    }
+    return ,$out.ToArray()
+}
+
+# Create a fresh disk image and write files to it.
+# $Files: ordered list of @{ Name = "decls.n8"; Path = host file; Type = "seq"|"prg" }
+function New-Nova128Disk {
+    param(
+        [Parameter(Mandatory)][string]$Path,
+        [Parameter(Mandatory)][object[]]$Files,
+        [ValidateSet("d64", "d81")][string]$Type = "d81",
+        [string]$Label = "nova128,n8"
+    )
+    $c1541 = Get-ViceTool "c1541"
+    if (Test-Path -LiteralPath $Path) { Remove-Item -LiteralPath $Path -Force }
+    $c1541Args = @("-format", $Label, $Type, $Path)
+    foreach ($f in $Files) {
+        $suffix = if ($f.Type -eq "seq") { ",s" } else { "" }
+        $c1541Args += @("-write", $f.Path, ($f.Name + $suffix))
+    }
+    $output = & $c1541 @c1541Args 2>&1
+    if ($LASTEXITCODE -ne 0 -or -not (Test-Path -LiteralPath $Path)) {
+        throw ("c1541 failed:`n" + ($output | Out-String))
+    }
+    $listing = (& $c1541 -attach $Path -list 2>&1) | Out-String
+    foreach ($f in $Files) {
+        if ($listing -notmatch ('"' + [regex]::Escape($f.Name) + '"\s+' + $f.Type)) {
+            throw "$($f.Name) ($($f.Type)) missing from $Path"
+        }
+    }
+}
+
+# Start x128 with a remote monitor. Returns a session object.
+function Start-Nova128X128 {
+    param(
+        [Parameter(Mandatory)][string]$Autostart,
+        [int]$Port = 6530,
+        [string]$Drive8Image,
+        [string]$Drive8Type = "1581",
+        [string]$Screenshot
+    )
+    $x128 = Get-ViceTool "x128"
+    $argList = @()
+    if ($Drive8Image) {
+        $argList += @("-drive8type", $Drive8Type, "-drive8truedrive", "-8", ('"' + $Drive8Image + '"'))
+    }
+    $argList += @("-autostart", ('"' + $Autostart + '"'), "-autostart-warp", "-warp",
+        "-sounddev", "dummy", "-remotemonitor",
+        "-remotemonitoraddress", "ip4://127.0.0.1:$Port")
+    if ($Screenshot) {
+        if (Test-Path -LiteralPath $Screenshot) { Remove-Item -LiteralPath $Screenshot -Force }
+        $argList += @("-exitscreenshotvicii", ('"' + $Screenshot + '"'))
+    }
+    $psi = [Diagnostics.ProcessStartInfo]::new()
+    $psi.FileName = $x128
+    $psi.Arguments = $argList -join ' '
+    $psi.UseShellExecute = $true
+    $psi.WindowStyle = [Diagnostics.ProcessWindowStyle]::Hidden
+    $process = [Diagnostics.Process]::Start($psi)
+
+    $client = $null
+    $deadline = [DateTime]::UtcNow.AddSeconds(10)
+    while ([DateTime]::UtcNow -lt $deadline) {
+        if ($process.HasExited) { throw "x128 exited before the remote monitor connected" }
+        try {
+            $client = [Net.Sockets.TcpClient]::new()
+            $client.Connect("127.0.0.1", $Port)
+            break
+        } catch {
+            if ($client) { $client.Dispose(); $client = $null }
+            Start-Sleep -Milliseconds 200
+        }
+    }
+    if (-not $client) { $process.Kill(); throw "could not connect to the VICE remote monitor" }
+    $stream = $client.GetStream()
+    $writer = [IO.StreamWriter]::new($stream, [Text.Encoding]::ASCII, 1024, $true)
+    $writer.NewLine = "`n"
+    $writer.AutoFlush = $true
+    return [pscustomobject]@{ Process = $process; Client = $client; Stream = $stream; Writer = $writer }
+}
+
+function Invoke-Nova128Monitor {
+    param([Parameter(Mandatory)]$Session, [Parameter(Mandatory)][string]$Command,
+        [int]$TimeoutMs = 5000)
+    $Session.Writer.WriteLine($Command)
+    $buffer = New-Object byte[] 65536
+    $text = ""
+    # Every monitor reply ends with a prompt such as "(C:$1c0d) ".
+    $deadline = [DateTime]::UtcNow.AddMilliseconds($TimeoutMs)
+    while ([DateTime]::UtcNow -lt $deadline) {
+        if ($Session.Stream.DataAvailable) {
+            $n = $Session.Stream.Read($buffer, 0, $buffer.Length)
+            if ($n -le 0) { break }
+            $text += [Text.Encoding]::ASCII.GetString($buffer, 0, $n)
+            if ($text -match '\(C:\$[0-9a-f]{4}\)\s*$') { break }
+        } else {
+            Start-Sleep -Milliseconds 50
+        }
+    }
+    return $text
+}
+
+# Read memory through the monitor. Returns byte[] (length = Count).
+function Read-Nova128Memory {
+    param([Parameter(Mandatory)]$Session, [int]$Address, [int]$Count)
+    $text = Invoke-Nova128Monitor $Session ("m `${0:X4} `${1:X4}" -f $Address, ($Address + $Count - 1))
+    $memory = @{}
+    foreach ($row in [regex]::Matches($text, "(?i)C:([0-9a-f]{4})((?:[ ]{1,2}[0-9a-f]{2}){1,16})")) {
+        $a = [Convert]::ToInt32($row.Groups[1].Value, 16)
+        foreach ($hex in ($row.Groups[2].Value.Trim() -split '\s+')) {
+            $memory[$a] = [Convert]::ToByte($hex, 16); $a++
+        }
+    }
+    $bytes = New-Object byte[] $Count
+    for ($i = 0; $i -lt $Count; $i++) {
+        if (-not $memory.ContainsKey($Address + $i)) {
+            throw ("monitor did not return `${0:X4}; response: {1}" -f ($Address + $i), $text)
+        }
+        $bytes[$i] = $memory[$Address + $i]
+    }
+    return ,$bytes
+}
+
+# Poll the test mailbox ($1BF0) until it reports PASS or FAIL. Returns its
+# 16 bytes. Resumes emulation between polls.
+function Wait-Nova128Mailbox {
+    param([Parameter(Mandatory)]$Session, [int]$TimeoutSeconds = 60)
+    $deadline = [DateTime]::UtcNow.AddSeconds($TimeoutSeconds)
+    while ($true) {
+        Start-Sleep -Seconds 1
+        $mb = Read-Nova128Memory $Session 0x1BF0 16
+        if ($mb[0] -eq 0x4E -and $mb[1] -eq 0x38 -and ($mb[3] -eq 0xA5 -or $mb[3] -eq 0xFA)) {
+            return ,$mb
+        }
+        if ([DateTime]::UtcNow -ge $deadline) {
+            $state = if ($mb[0] -eq 0x4E) { "status `$" + $mb[3].ToString("X2") } else { "never initialized" }
+            throw "mailbox did not finish within $TimeoutSeconds s ($state)"
+        }
+        Invoke-Nova128Monitor $Session "x" | Out-Null
+    }
+}
+
+# Let the program finish printing, then quit x128 (writes any exit screenshot).
+function Stop-Nova128X128 {
+    param([Parameter(Mandatory)]$Session, [int]$SettleSeconds = 2)
+    try {
+        if ($SettleSeconds -gt 0) {
+            Invoke-Nova128Monitor $Session "x" | Out-Null
+            Start-Sleep -Seconds $SettleSeconds
+            Invoke-Nova128Monitor $Session "m 0000 0000" | Out-Null
+        }
+        $Session.Writer.WriteLine("quit")
+        $Session.Writer.Dispose()
+        $Session.Client.Dispose()
+        if (-not $Session.Process.WaitForExit(10000)) { throw "x128 did not exit" }
+    } finally {
+        if (-not $Session.Process.HasExited) { $Session.Process.Kill(); $Session.Process.WaitForExit() }
+    }
+}
+
+Export-ModuleMember -Function Get-ViceTool, Invoke-Nova128Link, Get-Nova128Label,
+    ConvertTo-Nova128Petscii, New-Nova128Disk, Start-Nova128X128, Invoke-Nova128Monitor,
+    Read-Nova128Memory, Wait-Nova128Mailbox, Stop-Nova128X128
diff --git a/newLang/scripts/verify-source-test.ps1 b/newLang/scripts/verify-source-test.ps1
new file mode 100644
index 0000000..0474a61
--- /dev/null
+++ b/newLang/scripts/verify-source-test.ps1
@@ -0,0 +1,64 @@
+# E02-S01: run the source-reader test in x128 (1581 true drive) and compare
+# every result record with the host-computed expectations.
+[CmdletBinding()]
+param([int]$Port = 6531, [int]$TimeoutSeconds = 180)
+
+$ErrorActionPreference = "Stop"
+$project = Split-Path $PSScriptRoot -Parent
+Import-Module (Join-Path $PSScriptRoot "lib\Nova128Test.psm1") -Force
+& (Join-Path $PSScriptRoot "build-source-test.ps1")
+
+$out = Join-Path $project "build\source-test"
+$disk = Join-Path $out "source-test.d81"
+$screenshot = Join-Path $out "source-test-vicii.png"
+$expected = Get-Content -Raw (Join-Path $out "expected.json") | ConvertFrom-Json
+
+$session = Start-Nova128X128 -Autostart $disk -Drive8Image $disk -Port $Port -Screenshot $screenshot
+try {
+    $mb = Wait-Nova128Mailbox $session -TimeoutSeconds $TimeoutSeconds
+    $count = $mb[8]
+    $table = $mb[9] + 256 * $mb[10]
+    if ($count -ne $expected.Count) { throw "program ran $count fixtures, host expects $($expected.Count)" }
+    $raw = Read-Nova128Memory $session $table (16 * $count)
+} finally {
+    Stop-Nova128X128 $session
+}
+
+$failures = @()
+for ($i = 0; $i -lt $count; $i++) {
+    $r = $raw[(16 * $i)..(16 * $i + 15)]
+    $e = $expected[$i]
+    $got = [ordered]@{
+        code = $r[0]; dos = $r[1]; kernal = $r[2]; line = $r[3] + 256 * $r[4]; col = $r[5]
+        ldtnd = $r[6]; lines = $r[7] + 256 * $r[8]; len = $r[9] + 256 * $r[10]
+        s1 = $r[11]; s2 = $r[12]; flag = $r[13]; lastline = $r[14] + 256 * $r[15]
+    }
+    $problems = @()
+    if ($got.code -ne $e.code) { $problems += "code $($got.code) expected $($e.code)" }
+    if ($got.ldtnd -ne 0) { $problems += "$($got.ldtnd) file(s) left open" }
+    if ($got.flag -ne 1) {
+        $problems += $(if ($e.code -eq 0) { "passes differ" } else { "source delivered after failure" })
+    }
+    if ($e.code -eq 0) {
+        foreach ($k in "lines", "len", "s1", "s2") {
+            if ($got[$k] -ne $e.$k) { $problems += "$k $($got[$k]) expected $($e.$k)" }
+        }
+        if ($got.lastline -ne $e.lines) { $problems += "src_line_no $($got.lastline) expected $($e.lines)" }
+        $detail = "{0} lines, {1} bytes, fletcher {2:X2}{3:X2}" -f $got.lines, $got.len, $got.s1, $got.s2
+    } else {
+        if ($got.len -ne 0) { $problems += "src_len $($got.len) after failure" }
+        if ($null -ne $e.line -and ($got.line -ne $e.line -or $got.col -ne $e.col)) {
+            $problems += "position $($got.line):$($got.col) expected $($e.line):$($e.col)"
+        }
+        if ($null -ne $e.dos -and $got.dos -ne $e.dos) { $problems += "DOS $($got.dos) expected $($e.dos)" }
+        $detail = if ($e.code -eq 1) { "DOS {0}" -f $got.dos } else { "at {0}:{1}" -f $got.line, $got.col }
+    }
+    $status = if ($problems) { "FAIL" } else { "ok" }
+    Write-Host ("  {0,-11} code {1}  {2,-36} {3}" -f $e.name, $got.code, $detail, $status)
+    if ($problems) { $failures += "$($e.name): " + ($problems -join "; ") }
+}
+
+if ($mb[3] -ne 0xA5) { $failures += ("C128 reported FAIL ({0} fixture(s))" -f $mb[4]) }
+if ($failures) { throw ("source-reader verification failed:`n  " + ($failures -join "`n  ")) }
+Write-Host "verified source reader: $count fixtures match host expectations"
+Write-Host "screenshot: $screenshot"
diff --git a/newLang/src/common/diskio.inc b/newLang/src/common/diskio.inc
new file mode 100644
index 0000000..5b4e647
--- /dev/null
+++ b/newLang/src/common/diskio.inc
@@ -0,0 +1,12 @@
+; diskio.inc - logical file numbers and device used by src/compiler/diskio.s.
+
+.ifndef DISKIO_INC
+DISKIO_INC = 1
+
+DIO_DEVICE      = 8
+DIO_LFN_CMD     = 15            ; command/status channel: opened first, closed last
+DIO_LFN_IN      = 2             ; source input
+DIO_SA_IN       = 2
+DIO_STATUS_MAX  = 40            ; bytes kept from a drive status line
+
+.endif
diff --git a/newLang/src/common/source.inc b/newLang/src/common/source.inc
new file mode 100644
index 0000000..f8ff6ac
--- /dev/null
+++ b/newLang/src/common/source.inc
@@ -0,0 +1,20 @@
+; source.inc - source-reader limits and result codes (E02-S01).
+;
+; These are the reader's return codes. They are stable: E02-S04 maps each to
+; a user-facing Exxx diagnostic without renumbering them.
+
+.ifndef SOURCE_INC
+SOURCE_INC = 1
+
+SRC_MAX_LINE_BYTES = 80         ; logical line, excluding the $0D
+SRC_MAX_FILE_BYTES = 18999      ; whole file, including every $0D
+SRC_MAX_LINES      = 599
+SRC_EOL            = $0D
+
+SRC_OK                 = 0
+SRC_ERR_DISK           = 1      ; src_kernal_err / src_dos_code say why
+SRC_ERR_FILE_TOO_LARGE = 2      ; position of byte 19,000
+SRC_ERR_LINE_TOO_LONG  = 3      ; position of the 81st byte of the line
+SRC_ERR_TOO_MANY_LINES = 4      ; line 600, column 1
+
+.endif
diff --git a/newLang/src/compiler/diskio.s b/newLang/src/compiler/diskio.s
new file mode 100644
index 0000000..0a418c8
--- /dev/null
+++ b/newLang/src/compiler/diskio.s
@@ -0,0 +1,168 @@
+; diskio.s - KERNAL file and command-channel wrappers for the compiler.
+;
+; All routines are called from the bank-0 compiler state and reach the KERNAL
+; only through kcall_inline (mmu.s). They return C=1 on a KERNAL error with
+; A = the KERNAL error number. Callers own the open/close ordering: open the
+; command channel first, close it last (docs/architecture.md section 9).
+
+.setcpu "6502"
+.include "../common/c128.inc"
+.include "../common/diskio.inc"
+
+.import kcall_inline
+
+.export dio_open_cmd, dio_open_in, dio_chkin_in, dio_read_status
+.export dio_read_chunk, dio_clrchn, dio_close
+.export dio_count, dio_eof, dio_st, dio_dos_code, dio_status
+
+.import __DISKBUF_START__
+
+; ------------------------------------------------------------------ CODE
+.segment "CODE"
+
+; OPEN 15,8,15 with no name. Nothing is sent on the bus until it is read.
+dio_open_cmd:
+        jsr dio_setbank
+        lda #DIO_LFN_CMD
+        ldx #DIO_DEVICE
+        ldy #15
+        jsr kcall_inline
+        .word SETLFS
+        lda #$00
+        jsr kcall_inline
+        .word SETNAM
+        jsr kcall_inline
+        .word OPEN
+        rts
+
+; OPEN 2,8,2,name. In: A/X = name address (bank 0), Y = name length.
+dio_open_in:
+        sta dio_tmp
+        stx dio_tmp+1
+        sty dio_tmp+2
+        jsr dio_setbank
+        lda dio_tmp+2              ; SETNAM: A=len, X/Y=address
+        ldx dio_tmp
+        ldy dio_tmp+1
+        jsr kcall_inline
+        .word SETNAM
+        lda #DIO_LFN_IN
+        ldx #DIO_DEVICE
+        ldy #DIO_SA_IN
+        jsr kcall_inline
+        .word SETLFS
+        jsr kcall_inline
+        .word OPEN
+        rts
+
+dio_chkin_in:
+        ldx #DIO_LFN_IN
+        jsr kcall_inline
+        .word CHKIN
+        rts
+
+; Read the drive status line from channel 15 into dio_status (CR ended) and
+; its leading number into dio_dos_code. Leaves the default channels selected.
+dio_read_status:
+        lda #$FF
+        sta dio_dos_code
+        ldx #DIO_LFN_CMD
+        jsr kcall_inline
+        .word CHKIN
+        bcs @out
+        ldx #$00
+@read:  stx dio_tmp
+        jsr kcall_inline
+        .word CHRIN
+        ldx dio_tmp
+        sta dio_status,x
+        cmp #$0D
+        beq @parse
+        inx
+        cpx #DIO_STATUS_MAX - 1
+        bcc @read
+        lda #$0D
+        sta dio_status,x
+@parse: lda dio_status             ; two decimal digits -> binary
+        sec
+        sbc #'0'
+        cmp #10
+        bcs @bad
+        sta dio_tmp
+        asl a                      ; *10 = *8 + *2
+        asl a
+        adc dio_tmp
+        asl a
+        sta dio_tmp
+        lda dio_status+1
+        sec
+        sbc #'0'
+        cmp #10
+        bcs @bad
+        adc dio_tmp
+        sta dio_dos_code
+@bad:   jsr dio_clrchn
+        clc
+@out:   rts
+
+; Read up to 256 bytes from the current input channel into DISKBUF.
+; Out: dio_count (0 = 256), dio_eof ($40 at end of file), dio_st (ST with
+; the EOI bit removed; non-zero means a read error).
+dio_read_chunk:
+        jsr kcall_inline
+        .word dio_chunk_sys
+        rts
+
+dio_clrchn:
+        jsr kcall_inline
+        .word CLRCHN
+        rts
+
+; CLOSE the logical file in A.
+dio_close:
+        jsr kcall_inline
+        .word CLOSE
+        rts
+
+dio_setbank:
+        lda #$00                   ; data and filename in bank 0
+        tax
+        jsr kcall_inline
+        .word SETBNK
+        rts
+
+; ---------------------------------------------------------------- COMMON
+; Runs in the system state through kcall (system zero page, IRQs enabled),
+; so it uses only absolute variables.
+.segment "COMMON"
+dio_chunk_sys:
+        lda #$00
+        sta dio_count
+        sta dio_eof
+        sta dio_st
+@loop:  jsr CHRIN
+        ldx dio_count
+        sta __DISKBUF_START__,x
+        inc dio_count
+        jsr READST
+        beq @more
+        tax
+        and #$BF                   ; everything except EOI is an error
+        sta dio_st
+        txa
+        and #$40
+        sta dio_eof
+        rts
+@more:  lda dio_count
+        bne @loop                  ; stop after 256 bytes (count wraps to 0)
+        rts
+
+dio_count:      .byte $00
+dio_eof:        .byte $00
+dio_st:         .byte $00
+
+; ------------------------------------------------------------------- BSS
+.segment "BSS"
+dio_dos_code:   .res 1
+dio_tmp:        .res 3
+dio_status:     .res DIO_STATUS_MAX
diff --git a/newLang/src/compiler/mmu.s b/newLang/src/compiler/mmu.s
index db845f7..ede2cca 100644
--- a/newLang/src/compiler/mmu.s
+++ b/newLang/src/compiler/mmu.s
@@ -28,13 +28,14 @@
 .export mmu_init, mmu_bank0, mmu_bank1, mmu_system, mmu_shutdown
 .export kcall, kcall_inline, kc_target
 .export mmu_nmi_guard, mmu_nmi_count
-.export mmu_peek1, mmu_poke1
-.exportzp mmu_ptr
+.export mmu_peek1, mmu_poke1, mmu_copy_to1
+.exportzp mmu_ptr, mmu_src
 .export mmu_sys_cr, mmu_sys_rcr, mmu_sys_p0l, mmu_sys_p0h
 .export mmu_sys_p1l, mmu_sys_p1h, mmu_sys_nmi, mmu_comp_rcr
 
 .segment "ZEROPAGE"
 mmu_ptr:        .res 2             ; bank-1 access pointer (private page)
+mmu_src:        .res 2             ; common-RAM source for mmu_copy_to1
 
 ; ------------------------------------------------------------------ CODE
 .segment "CODE"
@@ -229,6 +230,19 @@ mmu_poke1:
         sta (mmu_ptr),y
         jmp mmu_bank0
 
+; Copy X bytes (X=0 means 256) from (mmu_src) to bank1[(mmu_ptr)]. The
+; source must be visible from bank 1: common RAM or $0000-$1FFF. Call from
+; the bank-0 state; returns in it. Clobbers A/X/Y; pointers unchanged.
+mmu_copy_to1:
+        jsr mmu_bank1
+        ldy #$00
+@copy:  lda (mmu_src),y
+        sta (mmu_ptr),y
+        iny
+        dex
+        bne @copy
+        jmp mmu_bank0
+
 ; Compact form: JSR kcall_inline / .word target. Preserves A/X/Y in, then
 ; behaves exactly like kcall.
 kcall_inline:
diff --git a/newLang/src/compiler/source.s b/newLang/src/compiler/source.s
new file mode 100644
index 0000000..482a75d
--- /dev/null
+++ b/newLang/src/compiler/source.s
@@ -0,0 +1,341 @@
+; source.s - buffered PETSCII source reader (E02-S01).
+;
+; src_load reads one SEQ file from device 8 into the bank-1 source cache
+; (SOURCE segment, D118), checking the editor-profile limits as bytes arrive.
+; Every pass then calls src_rewind and src_next_line, which replay the cache
+; one logical line at a time into src_line (common RAM). Bytes are not
+; translated: PETSCII in, PETSCII out. Only the line terminator is consumed.
+;
+; Lines and columns are 1-based. A file that ends without $0D still has its
+; last line. All routines run in the bank-0 compiler state.
+
+.setcpu "6502"
+.include "../common/source.inc"
+.include "../common/diskio.inc"
+
+.import mmu_copy_to1, mmu_bank0, mmu_bank1
+.importzp mmu_ptr, mmu_src
+.import dio_open_cmd, dio_open_in, dio_chkin_in, dio_read_status
+.import dio_read_chunk, dio_clrchn, dio_close
+.import dio_count, dio_eof, dio_st, dio_dos_code
+.import __DISKBUF_START__
+
+.export src_load, src_rewind, src_next_line
+.export src_line, src_line_len, src_line_no
+.export src_valid, src_len, src_lines
+.export src_err_line, src_err_col, src_kernal_err, src_dos_code
+
+; ------------------------------------------------------------------ CODE
+.segment "CODE"
+
+; Load a source file.
+;   in:  A/X = filename address (bank 0), Y = filename length
+;   out: C=0, A=SRC_OK, src_len/src_lines set, src_valid=1
+;        C=1, A=SRC_ERR_*, src_err_line/col (limit errors) or
+;             src_kernal_err/src_dos_code (disk errors); src_valid=0, src_len=0
+; Channels 2 and 15 are closed on every path.
+src_load:
+        sta name_ptr
+        stx name_ptr+1
+        sty name_len
+        lda #$00
+        ldx #state_end - state_start - 1
+@clr:   sta state_start,x
+        dex
+        bpl @clr
+
+        jsr open_source
+        bcc @chunk
+        cmp #$00                   ; A=0: command channel never opened
+        beq @fail_closed_disk
+        lda #SRC_ERR_DISK
+        bne @fail
+
+@chunk: jsr dio_read_chunk
+        jsr validate_chunk
+        bcs @limit_err
+        lda #<__DISKBUF_START__    ; append the chunk to the bank-1 cache
+        sta mmu_src
+        lda #>__DISKBUF_START__
+        sta mmu_src+1
+        clc
+        lda #<src_cache
+        adc src_len
+        sta mmu_ptr
+        lda #>src_cache
+        adc src_len+1
+        sta mmu_ptr+1
+        ldx dio_count
+        jsr mmu_copy_to1
+        lda dio_count              ; src_len += count (0 means 256)
+        bne @add
+        inc src_len+1
+        bne @added
+@add:   clc
+        adc src_len
+        sta src_len
+        bcc @added
+        inc src_len+1
+@added: lda dio_st
+        bne @read_err
+        lda dio_eof
+        beq @chunk
+
+        jsr close_all
+        lda v_lines
+        sta src_lines
+        lda v_lines+1
+        sta src_lines+1
+        lda #$01
+        sta src_valid
+        jsr src_rewind
+        lda #SRC_OK
+        clc
+        rts
+
+@read_err:                         ; ST error mid-file: ask the drive why
+        jsr dio_clrchn
+        jsr dio_read_status
+        lda dio_dos_code
+        sta src_dos_code
+        lda #SRC_ERR_DISK
+        bne @fail
+@fail_closed_disk:
+        lda #SRC_ERR_DISK
+        bne @fail_closed
+@limit_err:                        ; A = SRC_ERR_* from validate_chunk
+@fail:  pha
+        jsr close_all
+        pla
+@fail_closed:
+        sta src_err
+        lda #$00                   ; no partial source survives a failure
+        sta src_valid
+        sta src_len
+        sta src_len+1
+        sta src_lines
+        sta src_lines+1
+        jsr src_rewind
+        lda src_err
+        sec
+        rts
+
+; Open channel 15, then the source on channel 2, and select it for input.
+; C=0 on success. C=1 on failure with src_kernal_err/src_dos_code set and
+; A=0 if channel 15 could not be opened (nothing to close), else A=1.
+open_source:
+        jsr dio_open_cmd
+        bcc @cmd_open
+        sta src_kernal_err
+        lda #DIO_LFN_CMD           ; OPEN may have entered the file table
+        jsr dio_close
+        lda #$00
+        sec
+        rts
+@cmd_open:
+        lda name_ptr
+        ldx name_ptr+1
+        ldy name_len
+        jsr dio_open_in
+        bcs @kernal
+        jsr dio_read_status        ; e.g. 62,FILE NOT FOUND
+        bcs @kernal
+        lda dio_dos_code
+        sta src_dos_code
+        cmp #20
+        bcs @failed
+        jsr dio_chkin_in
+        bcc @ok
+@kernal:
+        sta src_kernal_err
+@failed:
+        lda #$01
+        sec
+@ok:    rts
+
+close_all:
+        jsr dio_clrchn
+        lda #DIO_LFN_IN
+        jsr dio_close
+        lda #DIO_LFN_CMD           ; command channel last
+        jmp dio_close
+
+; Check every byte of the chunk in DISKBUF against the limits.
+; C=1 with A=SRC_ERR_* and src_err_line/col on the first violation.
+validate_chunk:
+        ldx #$00
+@byte:  lda v_col
+        bne @in_line
+        inc v_lines                ; first byte of a new line
+        bne :+
+        inc v_lines+1
+:       lda v_lines+1
+        cmp #>(SRC_MAX_LINES + 1)
+        bcc @lines_ok
+        bne @too_many
+        lda v_lines
+        cmp #<(SRC_MAX_LINES + 1)
+        bcc @lines_ok
+@too_many:
+        lda #$01
+        sta src_err_col
+        lda #SRC_ERR_TOO_MANY_LINES
+        bne @error
+@lines_ok:
+@in_line:
+        inc v_total
+        bne :+
+        inc v_total+1
+:       lda v_total+1
+        cmp #>(SRC_MAX_FILE_BYTES + 1)
+        bcc @size_ok
+        bne @too_big
+        lda v_total
+        cmp #<(SRC_MAX_FILE_BYTES + 1)
+        bcc @size_ok
+@too_big:
+        ldy v_col
+        iny
+        sty src_err_col
+        lda #SRC_ERR_FILE_TOO_LARGE
+        bne @error
+@size_ok:
+        lda __DISKBUF_START__,x
+        cmp #SRC_EOL
+        bne @not_eol
+        lda #$00
+        sta v_col
+        beq @next
+@not_eol:
+        inc v_col
+        lda v_col
+        cmp #SRC_MAX_LINE_BYTES + 1
+        bcc @next
+        sta src_err_col
+        lda #SRC_ERR_LINE_TOO_LONG
+        bne @error
+@next:  inx
+        cpx dio_count              ; dio_count 0 = 256: stops when X wraps
+        bne @byte
+        clc
+        rts
+@error: pha
+        lda v_lines
+        sta src_err_line
+        lda v_lines+1
+        sta src_err_line+1
+        pla
+        sec
+        rts
+
+; Restart line delivery at the first line. Valid after any src_load.
+src_rewind:
+        lda #$00
+        sta src_pos
+        sta src_pos+1
+        sta src_line_no
+        sta src_line_no+1
+        sta src_line_len
+        rts
+
+; Deliver the next logical line.
+;   out: C=0: src_line = bytes without $0D, src_line_len, src_line_no
+;        C=1: end of source (or no valid source loaded)
+src_next_line:
+        lda src_valid
+        beq @eof
+        sec                        ; remaining = src_len - src_pos
+        lda src_len
+        sbc src_pos
+        sta remaining
+        lda src_len+1
+        sbc src_pos+1
+        sta remaining+1
+        ora remaining
+        beq @eof
+        lda remaining+1            ; fetch at most one line plus its $0D
+        bne @cap
+        lda remaining
+        cmp #SRC_MAX_LINE_BYTES + 1
+        bcc @limit
+@cap:   lda #SRC_MAX_LINE_BYTES + 1
+@limit: sta fetch_limit
+        clc
+        lda #<src_cache
+        adc src_pos
+        sta mmu_ptr
+        lda #>src_cache
+        adc src_pos+1
+        sta mmu_ptr+1
+        jsr src_fetch_line         ; Y = content length, X = bytes consumed
+        sty src_line_len
+        txa
+        clc
+        adc src_pos
+        sta src_pos
+        bcc :+
+        inc src_pos+1
+:       inc src_line_no
+        bne :+
+        inc src_line_no+1
+:       clc
+        rts
+@eof:   sec
+        rts
+
+; ---------------------------------------------------------------- COMMON
+; Runs with bank 1 mapped, so it lives in common RAM.
+.segment "COMMON"
+src_fetch_line:
+        jsr mmu_bank1
+        ldy #$00
+@copy:  cpy fetch_limit
+        beq @no_eol                ; last line without a final $0D
+        lda (mmu_ptr),y
+        cmp #SRC_EOL
+        beq @eol
+        sta src_line,y
+        iny
+        bne @copy
+@eol:   tya
+        tax
+        inx                        ; the $0D is consumed too
+        jmp mmu_bank0
+@no_eol:
+        tya
+        tax
+        jmp mmu_bank0
+
+fetch_limit:    .byte $00
+
+; ---------------------------------------------------------------- SOURCE
+; Bank-1 cache for the whole file. Never touched directly from bank 0.
+.segment "SOURCE"
+src_cache:      .res SRC_MAX_FILE_BYTES
+
+; --------------------------------------------------------------- SCRATCH
+.segment "SCRATCH"
+src_line:       .res SRC_MAX_LINE_BYTES
+
+; ------------------------------------------------------------------- BSS
+.segment "BSS"
+name_ptr:       .res 2
+name_len:       .res 1
+remaining:      .res 2
+src_line_len:   .res 1
+src_line_no:    .res 2
+src_pos:        .res 2
+
+state_start:                       ; cleared at the start of every src_load
+src_valid:      .res 1
+src_len:        .res 2
+src_lines:      .res 2
+src_err:        .res 1
+src_err_line:   .res 2
+src_err_col:    .res 1
+src_kernal_err: .res 1
+src_dos_code:   .res 1
+v_col:          .res 1
+v_lines:        .res 2
+v_total:        .res 2
+state_end:
diff --git a/newLang/tests/platform/map-skeleton.s b/newLang/tests/platform/map-skeleton.s
index 4782aac..bd27ae5 100644
--- a/newLang/tests/platform/map-skeleton.s
+++ b/newLang/tests/platform/map-skeleton.s
@@ -70,7 +70,7 @@ swstack_last:   .res 1
 
 .segment "TABLES"
 tables_first:   .res 1
-                .res $A000 - 2
+                .res $5500 - 2
 tables_last:    .res 1
 .ifdef OVERFLOW_TABLES
                 .res 1
diff --git a/newLang/tests/source/source-test.s b/newLang/tests/source/source-test.s
new file mode 100644
index 0000000..49f5604
--- /dev/null
+++ b/newLang/tests/source/source-test.s
@@ -0,0 +1,346 @@
+; E02-S01: source-reader test in x128.
+;
+; Loads each fixture from drive 8 with src_load. For a successful load it
+; replays the source twice (src_rewind + src_next_line) and records the line
+; count and a Fletcher-16 checksum of the delivered lines, each terminated by
+; $0D. For a failed load it records the error and checks that no source
+; survives. Every record is 16 bytes in `results`:
+;   +0 result code       +1 DOS status code   +2 KERNAL error
+;   +3 error line (2)    +5 error column      +6 LDTND after src_load
+;   +7 lines (2)         +9 src_len (2)       +11 Fletcher s1, +12 s2
+;   +13 flag: OK -> both passes identical; error -> next_line gave EOF
+;   +14 src_line_no after the last line (2)
+; Mailbox: PASS when every result code matches its expectation and every
+; flag is 1; MB_DATA+0 = fixture count, MB_DATA+1/2 = address of results.
+; The host checks every other field against values it computes itself.
+
+.setcpu "6502"
+.include "../../src/common/c128.inc"
+.include "../../src/common/mailbox.inc"
+.include "../../src/common/source.inc"
+
+.import mmu_init, mmu_bank0, mmu_shutdown, kcall_inline
+.import src_load, src_rewind, src_next_line
+.import src_line, src_line_len, src_line_no, src_len
+.import src_err_line, src_err_col, src_kernal_err, src_dos_code
+.import __COMPILER_ZP_PAGE__
+
+REC_SIZE = 16
+
+.segment "LOADADDR"
+        .word $1C01
+
+.segment "EXEHDR"
+        .word basic_end
+        .word 10
+        .byte $9E
+        .byte "7181"
+        .byte $00
+basic_end:
+        .word $0000
+
+.segment "MAILBOX"
+        .res MB_SIZE
+
+.segment "ZEROPAGE"
+fx_ptr:         .res 2             ; current fixture table entry
+rec_ptr:        .res 2             ; current result record
+
+.segment "STARTUP"
+.export test_entry, results
+test_entry:
+        php
+        sei
+        ldx #MB_SIZE - 1
+        lda #$00
+@clr:   sta MB_BASE,x
+        dex
+        bpl @clr
+        lda #MB_MAGIC0_VALUE
+        sta MB_MAGIC0
+        lda #MB_MAGIC1_VALUE
+        sta MB_MAGIC1
+        lda #MB_PROD_PLATFORM
+        sta MB_PRODUCER
+        lda #MB_ST_RUNNING
+        sta MB_STATUS
+
+        jsr mmu_init
+        jsr mmu_bank0
+
+        lda #$00
+        sta failures
+        sta fx_index
+        lda #<fixtures
+        sta fx_ptr
+        lda #>fixtures
+        sta fx_ptr+1
+        lda #<results
+        sta rec_ptr
+        lda #>results
+        sta rec_ptr+1
+
+@next:  ldy #0                     ; entry: name lo, name hi, length, expected
+        lda (fx_ptr),y
+        sta name_lo
+        iny
+        lda (fx_ptr),y
+        sta name_hi
+        iny
+        lda (fx_ptr),y
+        sta name_len
+        iny
+        lda (fx_ptr),y
+        sta expected
+        jsr run_fixture
+        clc
+        lda fx_ptr
+        adc #4
+        sta fx_ptr
+        bcc :+
+        inc fx_ptr+1
+:       clc
+        lda rec_ptr
+        adc #REC_SIZE
+        sta rec_ptr
+        bcc :+
+        inc rec_ptr+1
+:       inc fx_index
+        lda fx_index
+        cmp #FIXTURE_COUNT
+        bne @next
+
+        jsr mmu_shutdown
+        lda #FIXTURE_COUNT
+        sta MB_DATA+0
+        lda #<results
+        sta MB_DATA+1
+        lda #>results
+        sta MB_DATA+2
+        lda failures
+        sta MB_CODE
+        ldy #ok_msg - messages
+        lda failures
+        bne @fail
+        lda #MB_ST_PASS
+        bne @report
+@fail:  ldy #fail_msg - messages
+        lda #MB_ST_FAIL
+@report:
+        sta MB_STATUS
+        plp
+@print: lda messages,y
+        beq @end
+        sty print_y
+        jsr CHROUT
+        ldy print_y
+        iny
+        bne @print
+@end:   rts
+
+.segment "CODE"
+
+; Load one fixture and fill its record (rec_ptr).
+run_fixture:
+        ldx #REC_SIZE - 1
+        lda #$00
+@zero:  sta record,x
+        dex
+        bpl @zero
+
+        jsr show_name
+        lda name_lo
+        ldx name_hi
+        ldy name_len
+        jsr src_load
+        sta record+0
+        lda src_dos_code
+        sta record+1
+        lda src_kernal_err
+        sta record+2
+        lda src_err_line
+        sta record+3
+        lda src_err_line+1
+        sta record+4
+        lda src_err_col
+        sta record+5
+        lda __COMPILER_ZP_PAGE__ * 256 + LDTND   ; system ZP via the swap
+        sta record+6
+        lda src_len
+        sta record+9
+        lda src_len+1
+        sta record+10
+
+        lda record+0
+        bne @failed
+        jsr replay                 ; pass A
+        lda count
+        sta record+7
+        lda count+1
+        sta record+8
+        lda s1
+        sta record+11
+        lda s2
+        sta record+12
+        lda src_line_no
+        sta record+14
+        lda src_line_no+1
+        sta record+15
+        jsr replay                 ; pass B must match exactly
+        lda count
+        cmp record+7
+        bne @check
+        lda count+1
+        cmp record+8
+        bne @check
+        lda s1
+        cmp record+11
+        bne @check
+        lda s2
+        cmp record+12
+        bne @check
+        inc record+13
+        bne @check
+@failed:
+        jsr src_rewind             ; nothing may be delivered after a failure
+        jsr src_next_line
+        bcc @check
+        inc record+13
+
+@check: lda record+0
+        cmp expected
+        bne @bad
+        lda record+13
+        cmp #$01
+        beq @store
+@bad:   inc failures
+@store: ldy #REC_SIZE - 1
+@copy:  lda record,y
+        sta (rec_ptr),y
+        dey
+        bpl @copy
+        lda record+0
+        ora #'0'
+        jsr kcall_inline
+        .word CHROUT
+        lda #$0D
+        jsr kcall_inline
+        .word CHROUT
+        rts
+
+; One pass over the source: count lines, Fletcher-16 over line bytes + $0D.
+replay: lda #$00
+        sta count
+        sta count+1
+        sta s1
+        sta s2
+        jsr src_rewind
+@line:  jsr src_next_line
+        bcs @done
+        inc count
+        bne :+
+        inc count+1
+:       ldy #$00
+@byte:  cpy src_line_len
+        beq @eol
+        lda src_line,y
+        jsr fletcher
+        iny
+        bne @byte
+@eol:   lda #SRC_EOL
+        jsr fletcher
+        jmp @line
+@done:  rts
+
+; s1 = (s1 + A) mod 255; s2 = (s2 + s1) mod 255. Preserves Y.
+fletcher:
+        clc
+        adc s1
+        adc #$00                   ; end-around carry: 256 = 1 (mod 255)
+        cmp #$FF
+        bne :+
+        lda #$00
+:       sta s1
+        clc
+        adc s2
+        adc #$00
+        cmp #$FF
+        bne :+
+        lda #$00
+:       sta s2
+        rts
+
+show_name:
+        ldy #$00
+@ch:    cpy name_len
+        beq @sp
+        lda name_lo
+        sta @rd+1
+        lda name_hi
+        sta @rd+2
+@rd:    lda $FFFF,y                ; patched
+        sty print_y
+        jsr kcall_inline
+        .word CHROUT
+        ldy print_y
+        iny
+        bne @ch
+@sp:    lda #' '
+        jsr kcall_inline
+        .word CHROUT
+        rts
+
+.segment "RODATA"
+; name address, name length, expected result code
+fixtures:
+        .word f_decls
+        .byte f_decls_end - f_decls, SRC_OK
+        .word f_nofinal
+        .byte f_nofinal_end - f_nofinal, SRC_OK
+        .word f_edge
+        .byte f_edge_end - f_edge, SRC_OK
+        .word f_longln
+        .byte f_longln_end - f_longln, SRC_ERR_LINE_TOO_LONG
+        .word f_manyln
+        .byte f_manyln_end - f_manyln, SRC_ERR_TOO_MANY_LINES
+        .word f_big
+        .byte f_big_end - f_big, SRC_ERR_FILE_TOO_LARGE
+        .word f_missing
+        .byte f_missing_end - f_missing, SRC_ERR_DISK
+        .word f_decls
+        .byte f_decls_end - f_decls, SRC_OK     ; again, after failures
+FIXTURE_COUNT = (* - fixtures) / 4
+
+; Unshifted PETSCII letters ($41-$5A) are what c1541 stores for lowercase.
+f_decls:   .byte "DECLS.N8"
+f_decls_end:
+f_nofinal: .byte "NOFINAL.N8"
+f_nofinal_end:
+f_edge:    .byte "EDGE.N8"
+f_edge_end:
+f_longln:  .byte "LONGLN.N8"
+f_longln_end:
+f_manyln:  .byte "MANYLN.N8"
+f_manyln_end:
+f_big:     .byte "BIG.N8"
+f_big_end:
+f_missing: .byte "MISSING.N8"
+f_missing_end:
+
+messages:
+ok_msg:    .byte "NOVA128 SOURCE TEST OK", $0D, $00
+fail_msg:  .byte "NOVA128 SOURCE TEST FAIL", $0D, $00
+
+.segment "BSS"
+results:        .res REC_SIZE * FIXTURE_COUNT
+record:         .res REC_SIZE
+failures:       .res 1
+fx_index:       .res 1
+name_lo:        .res 1
+name_hi:        .res 1
+name_len:       .res 1
+expected:       .res 1
+count:          .res 2
+s1:             .res 1
+s2:             .res 1
+print_y:        .res 1