Reverse-Engineering the TI-84 Plus OS: System Architecture and Disassembly Notes
By
siraben
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The bagel they save for the regulars. Don't skim, savour.
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Summary
Reverse-engineering notes for the TI-84 Plus calculator OS (version 2.55MP), a Z80-based system. The article documents the system architecture, including the Zilog Z80 CPU with 16-bit address bus and 64 KiB logical space, hardware flash/RAM paging, and a Ghidra project setup for disassembly and decompilation analysis of the 1 MiB ROM dump.
Key quotes
· 3 pulledTarget: ti84plus.rom (1 MiB flash dump). OS self-identifies as 2.55MP.
CPU: Zilog Z80 (16-bit address bus, 64 KiB logical space) with hardware flash/RAM paging.
Confidence is flagged: [confirmed] = verified in disassembly/decompiler; [standard] = matches documented TI-83
Reverse-engineering notes for the TI-84 Plus calculator OS (2.55MP), a Z80 system.
