@KennyPowers has an interesting accelerator which puts a ROM in that space.
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MicroMac Power WorkStation - Did anyone ever buy one?
- Thread starter olePigeon
- Start date
No dates I can readily see on board. Do you have a thread to link about this one?
No dedicated thread, but maybe I should make one to try an identify it once and for all. There aren't any identifying markings on it, though Bolle pointed out that that particular warranty sticker hiding how much they're OCing the CPU was typically used on Novy accelerators. There are a lot of obviously hand-soldered components (and R403 is just a piece of wire). Also, the card gives nonsense clockspeed numbers in Speedometer and Clock-o-meter, but runs stabily. It works and sees the 16MB of onboard RAM without any drivers or software...LCII's onboard RAM is ignored. There's also a footprint for a single 72-pin SIMM in place of the 4 30-pin SIMMs.
Definitely start up a thread with pics of both sides of the board. Very, very interesting, buzzing connections between 30pin bank and 72pin footprint would be much appreciated. I've got graphics of such a conversion. Long running project, so confirming that diagram should be a whole lot easier than starting from scratch. 
I have too many other projects on the bench right now to dig that machine out, take it apart, and buzz the RAM slotsDefinitely start up a thread with pics of both sides of the board. Very, very interesting, buzzing connections between 30pin bank and 72pin footprint would be much appreciated. I've got graphics of such a conversion. Long running project, so confirming that diagram should be a whole lot easier than starting from scratch.
. Here's a good picture of the back of the board though:
It took me 3 years, but I believe I've finally found the dual-slot PDS adapter that was an option with the Power Workstation:
There's no programmable logic on it...just a single hex inverter, and near as I can tell, none of the inverted signals are actually used. Only two of the inverters in the 74F04 are used, with both taking the signal from the PDS pin circled in red in the first picture as input (I couldn't find an LC PDS pinout). One of the inverted signals goes through R1B and then appears to go nowhere. The other inverter's output goes to the unconnected side of R2B. I wonder what all that stuff on the right side of the board was for? Aside from that, it appears to be a completely passive adapter. I didn't check all 96 PDS pins, but I checked several of them, and each pin I tested on the male slot was connected directly to the same pin on each of the female slots.
I haven't tried using it yet. Micromac's site specifically mentions using the adapter with a "specially modified MicroMac ThunderCache accelerator". Two ThunderCache accelerators were included in the lot with this adapter, and everything was said to have been "pulled from working installs". I couldn't get any further details about the machine this was pulled from though.
There's no programmable logic on it...just a single hex inverter, and near as I can tell, none of the inverted signals are actually used. Only two of the inverters in the 74F04 are used, with both taking the signal from the PDS pin circled in red in the first picture as input (I couldn't find an LC PDS pinout). One of the inverted signals goes through R1B and then appears to go nowhere. The other inverter's output goes to the unconnected side of R2B. I wonder what all that stuff on the right side of the board was for? Aside from that, it appears to be a completely passive adapter. I didn't check all 96 PDS pins, but I checked several of them, and each pin I tested on the male slot was connected directly to the same pin on each of the female slots.
I haven't tried using it yet. Micromac's site specifically mentions using the adapter with a "specially modified MicroMac ThunderCache accelerator". Two ThunderCache accelerators were included in the lot with this adapter, and everything was said to have been "pulled from working installs". I couldn't get any further details about the machine this was pulled from though.
@KennyPowers Hmm. I wonder if the seller has the rest of the machines still?
@KennyPowers I just messaged the seller on eBay. They said they might still have access to the machine from where they pulled the adapter and upgrades. Hopefully they'll keep in contact and let me know. 
Sounds like you got a more helpful response than I did@KennyPowers I just messaged the seller on eBay. They said they might still have access to the machine from where they pulled the adapter and upgrades. Hopefully they'll keep in contact and let me know.
Their exact reply was, "Maybe but not sure when i will get them." So who knows.Sounds like you got a more helpful response than I did
Oh nice @KennyPowers you picked that listing up? Seems this might be straightforward to clone. Any chance it physically fits with two cards in an LC with case closed?
It would be straightforward to clone, but I suspect it will only work with either very simple, or very specific accelerators.
Nope...it doesn't even fit in an LC without any cards installed.
I've poked at it a bit more, and I was wrong about this (shocking). The clock signal coming in to the adapter goes to two separate inverters in the 74F004. R1B and R2B control whether the adjacent slot receives the unmodified clock signal from the main logic board, or if it receives an inverted clock signal passed through a ~22ohm damping resistor, which to my simple brain means the clock signal for that slot will be delayed by one half cycle? In my pictures, the top slot has a resistor installed, and the clock pin of that slot gets the inverted logic board clock passed through that resistor. However, R2B next to the lower slot has the bottom pads bridged, meaning the lower slot gets the unmodified clock signal directly from the logic board.
So basically, it looks like that stuff on the right end of the board allows you to independently delay/invert the clock signal going to each PDS slot. The Power Workstation manual says the accelerator should go in the lower slot, so it seems to be delaying the clock for any expansion card installed in the top slot. I suppose if you wanted to install those the other way around, you could simply move the resistor. Also, maybe this would allow tweaking timings for specific cards
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