topic Seeking info - Motorola SC44125P microcontroller in 8-bit Microcontrollers

Seeking info - Motorola SC44125P microcontroller

meterman1980 — Thu, 09 Apr 2020 05:15:57 GMT

I'm hoping someone can help me out with this vintage 1980s microcontroller - the Motorola SC44125P.

It is clearly an OEM version of a 6800-class microprocessor (see attached picture for pinout; the highlighted pins are those that differ from a stock MC6800).

The information I am after specifically:

Confirmation of which MC6800 variant this chip is based on (6800 / 6801 / 6805 / 6809 etc.), so I can look up the correct opcode table.

Presence and size of onboard ROM and method by which said ROM can be read out.

Re: Seeking info - Motorola SC44125P microcontroller

vicentegomez — Wed, 15 Apr 2020 18:35:24 GMT

Sorry, I do not have data of this part.

Regards

Vicente

Re: Seeking info - Motorola SC44125P microcontroller

meterman1980 — Sat, 27 Mar 2021 18:50:05 GMT

I asked on another forum and after some discussion and examination of the accompanying EPROM code, it was determined that the code uses the 6801 instruction set.

There were no calls that would redirect to internal RAM or ROM, so these two sections are unused. One example of this part was 'decapped' and was revealed to have a 6800 die inside the chip.

So, the SC44125 is a customized 6800 with 6801 instruction set and hard-wired address / data pins.