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tmerritt df11857075 Promote Xevious (U) and Zanac (U) from _wip/ to NROM/

- Xevious (U): Promoted from _wip/NROM/Xevious (U)/ to NROM/Xevious (U)/
  - Pass 3 complete: 34.5% code coverage, 143 semantic entry points,
    4 named data tables, ~20 semantic ZP aliases
  - NROM mapper 0, 32 KB PRG, 8 KB CHR, horizontal mirroring

- Zanac (U): Promoted from _wip/UNROM/Zanac (U)/ to NROM/Zanac (U)/
  - Pass 3 complete: 34.5% code coverage (bank 7 only), 133 semantic
    entry points, 26 named data tables, 14 semantic ZP aliases
  - UNROM mapper 2, 128 KB PRG (8 banks), no CHR
  - Bank 7 fixed at CPU -; banks 0-6 switchable at 000-
  - Bank 7 assembled separately as prg.07.s with .org

Both projects build byte-identical. Updated root README.md inventory,
per-project details, and WIP.md accordingly.

Move Zanac (U) to UNROM/ mapper directory

Zanac (U) is a UNROM (mapper 2) game, not NROM (mapper 0). Move it to
the correct mapper directory and update README.md and WIP.md references
accordingly. Update project counts in WIP.md (857->856 total, UNROM
98->97 projects).

Promote Mermaids of Atlantis (U) from _wip/ to MAPPER8/

Additional cleanup of Mermaids of Atlantis

2026-10-21 07:20:59 -04:00

3.9 KiB

Raw Blame History

Xevious (U)

Status

Pass 3 complete. All routine entry points (jsr/jmp targets) have semantic names, and all raw $XXXX call operands in jsr/jmp instructions have been replaced with label references (except 7 targets outside code range, kept as raw addresses). Major data tables and zero-page aliases have been named. The project builds and verifies byte-identical to the original ROM.

make assembles header.s, prg.s, chr.s, links them with ld65 and compares the result against rom.nes:

Byte-identical ROM verified.

Pass 1 results

Metric	Value
PRG size	32768 bytes (32 KB) at $8000-$FFFF
Code	11321 bytes (34.5%)
Data	21447 bytes (65.5%)
Instructions	5513
Routines/labels	795
Zero-page aliases	156 (in `locals.inc`)
Indirect dispatches	`jmp ($fe)` at $BA88 (table $BA8B, 16 entries), `jmp ($4)` at $CA07 (table $CA0A, 64 entries)

Pass 2 results

Metric	Value
`Label_XXXX` names replaced	781 labels → unique names
Raw `$XXXX` jsr/jmp operands replaced	466 → label references
Remaining raw `$XXXX` jsr/jmp	7 (targets outside code range)
Semantic zero-page aliases	~20 (in `locals.inc`)

Pass 3 results

Metric	Value
Semantic entry-point names	143 (Reset, NmiHandler, IrqHandler, InputRead, ObjInitCall, ObjMoveCall, ObjDrawCall, ObjUpdateCall, SetOamPtrs, WaitVblank, GameModeDispatch, ObjSpriteSetup, ObjCommonUpdate, etc.)
Internal branch labels	~574 (`Sub_XXXX` address-based, local to routines)
Named data tables	PatternData, SpriteAttrTable, JumpTable4, ResetVarTable
Semantic zero-page aliases	~20 (PPUCTRLShadow, ObjectX, ObjectY, ObjPtr, GameMode, Joypad1Cur, etc.)

Pass 1 notes

Two computed-dispatch mechanisms were recovered via declared jump tables:
- jmp ($fe) at $BA88 indexes a 16-entry table at $BA8B (targets in $BAAB–$BB20 range)
- jmp ($4) at $CA07 indexes a 64-entry table at $CA0A (targets mostly in $CA–$CB and $C0–$C3 ranges)
One branch at $E40A targets $E3B5, which falls inside the operand of jsr $CF2F at $E3B3. Emitted as .byte with an explanatory comment since the target cannot be a label.
Six addresses contain undocumented/illegal opcodes not decoded by the tracer: $9848, $A2C3, $CD89, $E0FF, $E3B5, $F230.

ROM

Property	Value
Format	iNES
Mapper	0
Board	NROM-256
Mirroring	Horizontal
Four-screen VRAM	no
Battery	no
PRG	32 KB (2 x 16 KB), mapped at CPU $8000-$FFFF
CHR	8 KB (1 x 8 KB)
Trainer	none
Footer	none
NMI vector	$FC4E
RESET vector	$FAF6
IRQ vector	$FF1D
ROM file	`Xevious (U).nes`
SHA-256	`1915fb1c30251de0c8f7913720a27b25d3ccef871851722a504d95fbb9d0ca7c`

Header notes

none

Open work

Pass 1 - complete. Code/data split produced; build verifies byte-identical.
Pass 2 - complete. All Label_XXXX names replaced with unique names; all raw $XXXX jsr/jmp operands replaced with label references (7 remain outside code range).
Pass 3 - complete. All 143 routine entry points have semantic names; ~574 internal branch labels remain as Sub_XXXX address-based names; ~20 zero-page aliases have semantic names; 4 data tables named.
Promotion to NROM/<name>/ once ready, as git mv.

Files

File	Purpose
`prg.s`	Pass 3 disassembly (semantic entry-point names + Sub_XXXX branch labels)
`header.s`	iNES header include
`chr.s`	CHR include
`prg.bin`	32768 bytes (32 KB) PRG image
`chr.bin`	8192 bytes (8 KB) CHR image
`rom.nes`	byte-identical copy of the original ROM
`linker.cfg`	HEADER / PRG / CHR memory areas
`symbols.inc`	NES hardware register names
`locals.inc`	zero-page aliases (semantic names applied at Pass 2/3)
`Makefile`	build and byte-identity check

3.9 KiB Raw Blame History Unescape Escape