Calmos RAM expansion CD101D1-3?

[progman32]

Hey all, new user here. Always been a PC guy, but these old Macs certainly have their charm. I recently rescued a 512k from a guy who was going to turn it into a MacQuarium. A little bit of basic maintenance and it's up and running . It was missing its mouse so I made an adapter for a USB mouse. I'll post that once it's reasonably polished. Anyway, this mac had a surprise inside. I was trying to disassemble it but I found the mainboard was catching on the case. Turns out there was an expansion board installed. It's a 2 meg expansion board by Calmos, CD101D1-3. Couldn't find anything substantial about Calmos, and even less about the board. This thing is bizarre because of how it's installed: two pin headers were SOLDERED RIGHT TO THE MAC'S 68k. The board then plugs into those headers. Also odd is that the expansion board has its own 68k - dual core mac! The Mac's own 68k is probably disabled, but I wonder if there was any special software written to take advantage of both CPUs. Anyone know any info about this monstrosity or Calmos?

Trying to attach a pic of the board, but it's not working ("File is invalid"). Oh well, my blog has lots of pics: http://giferrari.net/blog/?p=115

Video teardown of the Mac, with close up footage of the board:

 

[olePigeon]

I don't know anything about that one. Sounds like you may have gotten lucky and got not just a RAM expansion but some sort of CPU accelerator. Can you tell what model processor is on the upgrade and which is on the motherboard? It'll usually say right on the chip something like MC68020 or MC68030.

 

[Brett B.]

It looks like a memory expansion module of some sort. The processor is an 8MHz chip so no increase there... pretty neat though.

 

[progman32]

Thanks guys. The only difference between the CPUs is that the one on the expansion board is an MC68HC000P8 whereas the Mac one is just MC68000P8. Might try to reverse engineer the board a bit later, but the presence of the board makes the entire thing hard to disassemble (the mainboard doesn't slide out, I have to pry the board out from the bottom :O

Forgot to mention that the double-row header just to the right of the board's 68k connects via ribbon to a DB-25 on the back of the Mac. That's odd too.

 

[Gorgonops]

I would hazard a guess that the 25 pin connector is Mac Plus-compatible SCSI port. Looking at the board picture I don't see the NCR SCSI chip, although that square chip labeled "CALMOS" says "CA53C80" on it. The Plus used the DIP40 version of the NCR 5380, so... there you go. Custom Label SCSI.

 

[progman32]

Haha so basically I have a Mac Plus cleverly disguised as a 512k I'll have to rig up something to that SCSI then!