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ROM socket modifications

A project log for Stuart Conner's Simple TMS9995 board build

Stuart Conner's Simple TMS9995 board build

keithKeith 10/16/2022 at 17:510 Comments

Pin 1 isolated from 5V, then wired to A14 (pin 1 of RAM)

Pin 27 isolated from A14 (pin 1 of RAM), then wired to /WE (pin 27 of RAM).

Cut track on top side of board, from ROM pin 1 to pin 28 (VCC):

Next make the mods shown below:

The RAM is on the left, the ROM on the right. Note:
ROM pin 27 track cuts each side.
The track joining pins 1 joins the A14 track.
The ROM pin 27 is tied to RAM pin 28 (VCC), not 27 (/WE). The latter connection will cause the CPU to corrupt the ROM even if the code never tries to write to EEPROM addresses.

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