REFORGE
Atari 2600 / F264
BEING VERIFIED

ZERO-PAGE INDEXED RMW DISCARDS THE BASE READ AND WRAPS BEFORE BOTH WRITES

STATUS
BEING VERIFIED
AREA
Memory / cartridge
RECORDED
2026-07-16
PUBLIC SOURCE
Research dossier / finding 264
RECORD ID
atari2600-f264
SNAPSHOT
f114355884d03a2c

MOS manual section 6.2, Example 6.8 fixes zero-page indexed execution as opcode and operand reads, a discarded read at the unindexed zero-page base, then an effective access after adding X or Y with page-zero wrap. Pinned Stella revision 90d01ecb309b9c3317ca762078d4df40681e111b supplies the remaining NMOS RMW sequence for ASL/ROL/LSR/ROR/DEC/INC and stable SLO/RLA/SRE/RRA/DCP/ISC: read the wrapped operand, write the old byte, compute, then write the…

Raw traces, ROM material, local paths, and personal data are not part of this public record.