problem with MicroMac accelerator in SE

[YMK]

Cool!

 

[JDW]

...I started working back from each SIMM slot to the CPU and eventually found a bad via on each of those two data lines. I've repaired them and now have good continuity from the SIMM back to the CPU.

Congratulations on your successful repair!

Look forward to seeing Benchmarks (Norton Utilities System Info 3.5, Speedometer, etc.) when you have time!

 

[KennyPowers]

Should I dump the ROM from this accelerator? The EPROM is an Atmel AT27C512R, which is apparently supported by my programmer:

http://www.autoelectric.cn/MiniPro/TL866II_List.txt



I've only used my programmer for writing EPROMs for some breadboard projects and don't have a lot of experience dumping old ROMs. Is there any chance of damaging the ROM or that it might be copy-protected somehow?

Using the minipro CLI, it looks like a command like this might work?

minipro -p AT27C512R@DIP28 -x -r rom.bin

 

[KennyPowers]

Got it

 

[retr01]

Aha! Now we know who wrote that program. Benjamin!

 

[KennyPowers]

I loaded this thing up with 16MB of RAM and was about to put the machine back together for some benchmarks when that big empty FPU socket was staring at me. So, I ordered a 68882 off ebay...ETA March 8th-14th. I guess it's sat on my shelf for a year...I can wait a week or two more to play with it

 

[KennyPowers]

So the FPU arrived, I installed it, reassembled the machine, and fired it up. It was...flaky. Random, inconsistent instruction and bus errors, etc. Finally narrowed it down the 16MB of RAM I'd replaced the original 4MB on the accelerator with. I put the original four 1MB SIMMs back in, and now it's rock-solid. The 4MB SIMMs I tried *should* be compatible, so maybe one of them is bad? I only have four 4MB 30pin SIMMs to try unless I want to take apart my accelerated Classic...and I don't. Anyways, this thing is currently working great in its original configuration plus an FPU, so I'm happy

logic board and accelerator reassembled (with flaky 4MB SIMMs):


some Speedometer benchmarks:


nifty MicroMac boot screen (sorry about the vertical video):