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muPro 80

Bruce Tomlin

Experienced Member
Joined
Jan 6, 2010
Messages
327
Location
San Antonio, TX
muPro 80 was an 8080-based in-circuit emulator from around 1977 or so. I've found a few references to it from magazines back in the day, but it was mostly "this thing exists", with no attempt to review it or anything.

This is another thing I found long ago and only recently got around to properly looking at it. The biggest problem was that it was full of 2708 chips (there are two each of those DRAM and ROM boards in the photos), and I was really worried about frying the chips without a proper reader. I finally dumped a few weeks ago.

It has a 40-pin ground-planed ribbon cable that is apparently a straight-through emulator pod cable, a fly wire that may be some kind of trigger signal (or maybe an extra ground), and a serial port cable. The missing fuse thing in back isn't a problem because it was diked out on the inside. It uses an uncommon power cord, I think it was one that HP used a lot, and I found one at a hamfest. But no way am I turning it on until I've had the time to take it completely apart and repair the power supply, because in addition to being an old linear supply with big electrolytics, at some point one of the filter caps had a mud dauber cell on it.

The front panel seems to be a proper front panel that overrides the CPU signals, but I can't see its guts without taking everything apart. There is a piece of paper taped to the top of it that listed the three entry points for the programs in ROM. The 16K of ROM has an 8K assembler, a 5K editor, and a 3K linking loader. Startup code for the three are in the slack space after the editor and loader. The startup code clears all 16K of RAM and then copies the ROM program to RAM. There seems to be no consideration for restart vectors other than simply not using the first 64 bytes.

There is no sign that it ever had the disk system, and as far as I can tell the ROM programs had no storage other than supporting a paper tape punch. I have a hard time imagining using this system when it doesn't even attempt to keep your code in RAM, so maybe it was just used as a debugger. One of the references I read implied that the ROM programs were included for free (heh), and I guess you get what you pay for?

The ROM boards have a 25-wire jumper for programming. Apparently they had something rigged up that could take the whole board with all eight EPROM chips on it and program them all while in the sockets. They used two dozen pins of the bus just for this, but I think it was only intended to be used externally, so some might have been shared with other functions like DRAM refresh. Note the separate board with DRAM refresh circuitry! One interesting thing is that they had two 7905 regulators on the ROM boards, powering only four chips each with -5V.
 

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Here are some official photos of it. All I have is the main unit and the white cable. I suspect that the "pod" board is a one-to-one pinout with the target's 8080 socket.

This is the memory layout: (You might notice that I numbered the EPROMs in the "wrong" order.)
0000 8K DRAM
2000 8K DRAM
4000 8K ROM (roms 09-16) editor, linking loader, startup code
6000 8K ROM (roms 01-08) assembler

There's also a piece of paper taped to the top of it that says:
Code:
EDITOR          51BB
ASSEMBLER       5FDF
LINKING LOADER  51DD
 

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