Model and ROM information

Information regarding Model type, PCB code, ROM marking, ROM version and checksum is captured here. S. Adolph

  Note: I'll try to keep this list updated.  If anyone has comments or corrections to this please let me know.

What Kind of Model 100 or Tandy 102 do You Have?

Model 100

The first M100s were released with a custom ROM pinout, in agreement with the published schematic. Over time, Radio Shack changed the design to use standard 27C256 compable ROMs. Both variants use essentially the same ROM code. Clearly the schematic for these later variants was different due to the ROM pinout.

Later, versions of the M100 were produced for UK and EU markets. These M100 appear to use 27C256 compatible ROMs, but the ROM code differs from the USA version. The schematic for these versions had changes as the UK M100 had no modem function, and the EU version had a different modem.

Tandy 102

Tandy introduced the 102 from the beginning using a 23C256 compatible ROM. There is a published schematic available. the T102 main ROM had a few improvements and bug fixes compared to the standard M100 main ROM.

Later, versions of the T102 were produced for UK and EU markets. The ROM code again differs from the USA version.

Model Type Information

You can tell these variants apart by observing the presence of the modem, and by looking at the PCB itself. The ROMs will have a unique marking, as does the PCB. In some cases the Tandy product number is different as well. This information is captured in the below table.

M100

Variant	Product number	PCB code	ROM marking	ROM checksum	ROM image	Note
Early USA	26-3801/3802	PLX110CH1X	LH535618	A2D4	m100	This is the usual M100
Late USA	26-(3801)/3802	PLX110EH1X	3256C07-3J1	A2D4	same as above	Later version
EU	26-3801/3802	??	3256C05-3E1	A8AF	M100rom-e_Y2K	Different modem
UK	26-3801/3802	PLX120CH1X	3256E30-4C3	EEA4	m100UK_nomodem	no modem, BCR, similar as KC-85
EU? UK?	26-3801/3802	PLX120BH1X	3256E30-4F3	??	??	no modem, BCR, similar to KC-85

T102

Variant	Product number	PCB code	ROM marking	ROM checksum	ROM image	Note
USA	26-3803	PLX144FH1X	M53256-02	A8CA	t102_rom	This is the usual T102
EU	26-3803	PPPCG2007A*01	PB INT	B20F	T102_EU_modem	Different modem, QWERTY
UK	26-3803	??	??	XXXX	binary file	no modem