Brian K. White
UNITED STATES OF AMERICA • + Follow
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Description
M4ROM 27256 - Writable multi option rom module for EPSON PX-4, PX-8, TANDY 600, any Molex 78805 socket with standard pinout
Provides 4 virtual 32k EPROM from a single 128k flash chip, in a Molex 78802 form factor to fit in a Molex 78805 socket.
The pinout at the castellated edge contacts is standard 32Kx8 parallel mask rom, or the same as 27C256 without the VPP pin.
Compatible with TANDY Model 600, Epson PX-4, Epson PX-8, Kyotronic KC-85, and most other things that have a Molex 78805 socket such as Allen-Bradley PLCs, Intermec and Telexon hand terminals, etc.
This is NOT for TRS-80 Model 100, 102, or 200! For those, see the M4ROM_TANDY
The chip is written and re-writable using this programming adapter common to both M4ROM_27256 and M4ROM_TANDY.
How to program: http://github.com/bkw777/M4ROM
Schematic and Layout
https://github.com/bkw777/M4ROM
CAD-Custom parts and enclosures
https://github.com/bkw777/Molex78802_Module
Molex78802_PCB_28.stl
Feb 13,2023
1,251 views
M4ROM 27256 - Writable multi option rom module for EPSON PX-4, PX-8, TANDY 600, any Molex 78805 socket with standard pinout
Re-writable 4-bank virtual EPROM in Molex 78802 carrier to fit Molex 78805 socket with 27256 pinout.
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Published: Feb 13,2023
Standard PCB
Download Gerber file 11
BOM(Bill of materials)
Centroid file
PCBWay Donate 10% cost To Author
File Last Updated: 2025/11/18 (GMT+8)
File update record
2025-11-1811:30:00
Centroid file is updated.
2025-11-1811:30:00
Gerber file is updated.
2025-11-1810:58:01
Centroid file is updated.
2025-11-1810:58:01
Parts List (BOM) is updated.
2025-11-1810:58:01
Gerber file is updated.
2025-09-1905:02:41
Centroid file is updated.
2025-09-1905:02:41
Parts List (BOM) is updated.
2025-04-0110:48:03
Parts List (BOM) is updated.
2024-04-2004:45:44
CAD or technical drawing file is updated.
2024-01-0203:00:31
Gerber file is updated.
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