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Mostek 3870, possible to extract code?

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HHaase

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Yeah, we're talking real old-school microcontroller stuff here, and my guess is that what I'm looking to do is pretty much impossible.

But the old Mostek 3870 was a 1970's/1980's microcontroller with an internal masked ROM section to it. Later on they came out with the 38P70, which had an EPROM socket on the back of the chip. IIRC it used the old Fairchild F8 assembly language.

I'm looking to see if I can extract the code from the original 3870's, so that I can do repair work and burn it into an EPROM for the 'piggyback' version, to replace the original masked version if necessary.

Anybody ever worked with these antiques?
 

OlPhart

Member
I 1st worked with Z80s, so I'm familiar with that series. IIRC, the 3870 was Mosteks' version of the Z80. As such, it has no internal ROM of any kind... it predates that level of integration. I'd look for a (or several) 27xx chip(s) around it as the ROM/EPROM code storage. If it is the mask ROM version, you're right, extraction is impossible. You'll have to write a new controller/code to mime the behavior.

If 27xxs' are not damaged, they're fairly straightforward to read, but you'll need "old school" toys to do so. An EPROM programmer will read ROMs too. Good Hunting... <<<)))
 
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HHaase

New Member
Unfortunately, it really was that integrated in the 3870's where they had internal ROM right on the processor chip. Later versions used a 2716 that plugged into a socket that was actually on the top of the processor chip, but I need to get the data out of one with the internal ROM.

The older 3850's had separate ROM chips, which were a proprietary design, and these IIRC were a direct copy of the Fairchild F8 processor set.
 

jrr

New Member
I am currently working on reading these 3870s - hope to be able to have a replacement device for them in the near future running the original code. My project is pinball related,but should be able to cover other uses that the Mostek/Motorola 3870 was put to.

John :-#)#
 

alemi

New Member
Hello! At what point is the job of extracting the code?
I have a problem on a Fluke 8860A multimeter has a Mostek 3870 (MK14574P-5) damaged. To recover the functionality of it would be useful to extract the source code and put it on an external EPROM located on a 38P70. is it pratical possible?
Ale
 
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