Three motherboards over Plus' lifetime. What changed?

[Jens Larsen]

As the title says, there were three motherboard derivations, beginning in 1985, ending in 1987.
Does anyone know if changes were made with each permutation?
Curious...

 

[adespoton]

AI summary is rather inconclusive:

• Original Revision (1986):
  • Featured the original beige-colored case.
  • Used the Motorola 68000 processor running at 8 MHz.
  • Included 1 MB of RAM, expandable to 4 MB using 30-pin SIMMs.
  • Introduced the SCSI port, though it wasn't fully compliant with the finalized SCSI standard.
• Second Revision (1987):
  • The case color was changed to "Platinum" gray.
  • Minor updates were made to the motherboard to improve reliability and compatibility with peripherals.
  • Continued to use the same processor and memory configuration.
• Final Revision (Late 1980s):
  • Further refinements to the motherboard for better performance and stability.
  • Improved SCSI implementation, though still not fully compliant with the standard.
  • No significant changes to the processor or memory capabilities.

I had the final revision. The only changes I can remember being mentioned over the 1987 model were improved SCSI, an improved flyback converter, and a cheaper method of cold soldering the CRT power leads. That last one resulted in a recall, as over time, this batch of Pluses, having no fan, heated up to the point where the leads started to disconnect; you could whack the Plus on the side of the case to cause the wiring to settle and the display come back on, but as it heated up again, the screen would randomly turn off. Resoldering the leads was enough to fix the problem.

 

[luRaichu]

Why would you trust a machine to tell you about another machine?

 

[adespoton]

Why would you trust a machine to tell you about another machine?

I wouldn't, but it's a great way to jog your memory. And as long as there's no hallucinating going on, it's a useful way of looking up old documentation as long as you're using a model that cites its sources. This one did, but I couldn't validate the sources (again, trusting a server somewhere to serve me the correct documentation).

 

[Jens Larsen]

Hmm. Not sure what source you're quoting, but I know my Plus' motherboard was minted with the date "1985."

 

[finkmac]

AI summary is rather inconclusive:

i asked a fellow at the pub down the road and he said they moved random components about to mess with the repair guide writers.

 

[Jens Larsen]

Ah yes! Let's see wheat we can do to foul up the writers! Usually it's editors writers curse. Now it's the PCB layout designers!

 

[Durosity]

I'm not aware of any changes to the motherboard itself, but I think there was a few different ROM revisions during its production run... possibly that's what it's referring to?

 

[adespoton]

I'm not aware of any changes to the motherboard itself, but I think there was a few different ROM revisions during its production run... possibly that's what it's referring to?

There's different ROM revisions and different cases, but they swapped out a few components and changed a few assembly processes as well. AFAIK, (and I've only looked at a handful of boards from different Pluses, so I'm sure there's people on here who know a LOT more than I do, take anything I say as dim recollections and not authoritative), there were no actual layout design changes to the board.