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MicroMac MultiSpeed speed upgrade?
- Thread starter ObeyDaleks
- Start date
The board Phipli posted is the CPU dauterboard out of a PowerBook (170 I think). He was just showing the picture to illustrate that they eventually made MC versions of the 68030. It isn't the accelerator being discussed.Interesting board, strange connectors. What machine is it for, a PowerBook?
- has anyone identified a crystal on that board, I didn't see one right off?
- if no crystal's on board, then it's running on a system bus multiplier, which could be problematic.
Long term quest has been running the 68030/16Mhz Performer from my Drexel Plus at 32MHz. But such appears not to be feasible.
@Bolle has cloned it and tried hooking the 8MHz bus clock-doubling GAL to the 16MHz clock on the board. I'd hoped for success there for a very long time™, but timings appear to be too tight for it to work.
Markings appear to indicate 25MHz is a possibility, wondering about timing complications this case?
Incidentally there are two clock chips on that board which are the black rectangles on the right side labeled 50.000 - (CPU clock) and 31.3344M - (presumably the bus clock). A lot of Macs use that type of clock in case you ever need to identify one.
Heh.
Only reason that warranty void sticker is there is to hide that they overclocked some or all of their processors.
At least they were apparently warrantying the overclock
So I did some more research and I'm pretty much convinced that those jumpers don't have anything to do with the crystal frequency. I think the theory mentioned earlier was that jumper 2 was dividing the clock by 2. But I was able to find some (very blurry) pictures that show various configs of the card, including the same 16Mhz version with bridged jumper 3, and also another picture of 33Mhz version which had the jumper 2 bridged. So I'm not sure what those jumpers are for, but it doesn't look like they control the frequency sent to the processor. Which also makes sense since it's nowhere near the oscillator.
I'm now thinking a more likely candidate is the flip-flop IC on the right of the crystal. I think the only way to know for sure is to get a high-res photo of a 33Mhz board (per @avadondragon suggestion), and specifically the area around the oscillator. If anybody has one and is willing to post a pic, that would be awesome!
I'm now thinking a more likely candidate is the flip-flop IC on the right of the crystal. I think the only way to know for sure is to get a high-res photo of a 33Mhz board (per @avadondragon suggestion), and specifically the area around the oscillator. If anybody has one and is willing to post a pic, that would be awesome!
@KennyPowers How come there is so much hand soldering on your board? Did you take it apart? Did you remove all the resistors for some reason?Kenn
That's what I thought as well from looking at the picture.
You mean on that LCII accelerator? Don't want to derail this thread about the MultiSpeed, but I never noticed the soldering on those resistors. I've never taken a soldering iron to it myself. I've also never definitively identified that accelerator. There aren't any identifying markings on it. It's the accelerator that was in the MicroMac Power Workstation I got from my dad, which was advertised to include a ThunderCache accelerator, which looks kind of similar, but not identical from the few pictures I've found. Given the vaporware-ish nature of the Power Workstation, maybe that accelerator is also some kind of prototype or something that explains the hand soldering? I dunno. I don't know the whole history of that machine. My dad can't remember if he already had the accelerator before adding the Power Workstation expansion or not.
Strange. Yeah, the soldering doesn't look like it was done by someone used to doing surface mount soldering.
You are correct. I had my SE with MultiSpeed apart today and I took a look at it. My MultiSpeed has a 50Mhz oscillator. The output pin of that flip-flop is connected directly to the clock pins on the CPU and FPU. As you can see, the flip-flop is halving the oscillator's frequency:
I've looked at photos of MultiSpeeds with 33Mhz, 40Mhz, and 50Mhz oscillators, and don't see any major differences, and the flip-flop IC appears to be the same on all of them. That suggests two things:
- Either there was an unadvertised 20Mhz version or someone overclocked their 16Mhz version.
- The 33Mhz version that I can't find an example of maybe just had a 66Mhz oscillator?
