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Easy wifi display and keyboard for the HP-75c
09-24-2019, 07:49 AM (This post was last modified: 09-24-2019 07:54 AM by Martin Hepperle.)
Post: #17
RE: Easy wifi display and keyboard for the HP-75c
The IO-ROM consists of 3 ROMs (LEX numbers 0x4063 0x4064 0x4065). The main part of the KEYBOARD IS command is in the first ROM, but it refers at least to one routine in the second ROM. This should be combined into a single LEX file.

The ROM images can be disassembled with Everetts disassembler - I have done this only for the first ROM and can provide the listing as a starting point.
Comments for the code can be found in the printed IO-ROM listings, but these listings use macros from the KARMA HP-1000 assembler (like IF/THEN/ELSE) which are not available in the HP-85 assembler.
Therefore I prefer to disassemble the original ROMs and use the printed listings as a guideline for comments.

Note for hardware experts: It would still be interesting to design a modern ROM emulator for the HP-75 ... if the connector problem can be solved.

Martin
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RE: Easy wifi display and keyboard for the HP-75c - Martin Hepperle - 09-24-2019 07:49 AM



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