Tsunami motherboard L2 cache card?

[This Does Not Compute]

A while ago I had another Power Computing machine drop into my lap. It's a PowerTower Pro, and it looks like it's had some upgrades (as was common). But while poking around inside the system, I noticed that the L2 cache card slot is empty.

The PowerTower series is based on Apple's Tsunami architecture, just like the Power Mac 9500. Some research suggests it shipped with a 1MB L2 card. Does anyone know how to identify these? I know they have two notches that are evenly spaced, but some other Mac/clone models used modules that appear similar. Are these all the same? Any particular part numbers to look for? And if I drop in a G3 upgrade, would the L2 card even be necessary?

 

[retr01]

Yeah, @This Does Not Compute, it was shipped with a 1 MB L2 card. See the ad below from MacWorld's August 1997 issue on the inside front spread.

 

[XodiumRetro]

Just seeing this now and hmmmmm.

I'm kinda deep into building up my 9600 (though it's irrelevant now because mine has since been upgraded to a Kansas architecture board) and this whole rabbit hole makes me wonder if the L2 module for the PowerTower could be used on the 9600 for whatever reason. (Though that might be irrelevant as the Tsunami board in the 9600 already has onboard L2 cache). Because as far as I know, no 9600 shipped with that module installed. (The Tsunami board already had the aforementioned L2 onboard, and the Kansas board was really intended to have the L2 be on the CPU card itself.)

Also...

And if I drop in a G3 upgrade, would the L2 card even be necessary?

If my research on the Tsunami 9600 is any indication, no. Actually, the stock Apple/onboard L2 can be a detriment to a G3 CPU as oftentimes that L2 cache is slower than the L2 on the upgrade card itself. Thankfully I can at least verify that NewerTech's drivers (should you be looking at one of their cards for a G3 upgrade) actually dance around this and tell the system to look at the CPU card itself for L2, not the motherboard/cache slot. And assuming in the case of the PowerTower if it has no onboard L2, the system will automatically see the CPU's L2 and use that. But that's a wild guess.

 

[This Does Not Compute]

Just seeing this now and hmmmmm.

I'm kinda deep into building up my 9600 (though it's irrelevant now because mine has since been upgraded to a Kansas architecture board) and this whole rabbit hole makes me wonder if the L2 module for the PowerTower could be used on the 9600 for whatever reason. (Though that might be irrelevant as the Tsunami board in the 9600 already has onboard L2 cache). Because as far as I know, no 9600 shipped with that module installed. (The Tsunami board already had the aforementioned L2 onboard, and the Kansas board was really intended to have the L2 be on the CPU card itself.)

Also...

If my research on the Tsunami 9600 is any indication, no. Actually, the stock Apple/onboard L2 can be a detriment to a G3 CPU as oftentimes that L2 cache is slower than the L2 on the upgrade card itself. Thankfully I can at least verify that NewerTech's drivers (should you be looking at one of their cards for a G3 upgrade) actually dance around this and tell the system to look at the CPU card itself for L2, not the motherboard/cache slot. And assuming in the case of the PowerTower if it has no onboard L2, the system will automatically see the CPU's L2 and use that. But that's a wild guess.

Yeah, in doing some more research for the video I ultimately made on the PowerTower Pro, it sounds like they 1) did indeed ship with an L2 module, but 2) if you installed a G3 upgrade you often (but not always) needed to remove the L2 module. It seems that it came down to the design of the G3 card; XLR8 said you should pull the cache, whereas Sonnet did not. What I surmised from my own machine is that it had likely been upgraded back in the day, which explains the missing cache -- but when the owner reverted the upgrade, they forgot to put the cache back in. What I haven't been able to find are part numbers or any kind of compatibility matrix as to what cache modules came with/work in which systems.

 

[Fizzbinn]

A while ago I had another Power Computing machine drop into my lap. It's a PowerTower Pro, and it looks like it's had some upgrades (as was common). But while poking around inside the system, I noticed that the L2 cache card slot is empty.

The PowerTower series is based on Apple's Tsunami architecture, just like the Power Mac 9500. Some research suggests it shipped with a 1MB L2 card. Does anyone know how to identify these? I know they have two notches that are evenly spaced, but some other Mac/clone models used modules that appear similar. Are these all the same? Any particular part numbers to look for? And if I drop in a G3 upgrade, would the L2 card even be necessary?

I made a resource article on the topic of identifying Power Macintosh L2 cache modules!

https://tinkerdifferent.com/resources/ppc-macintosh-l2-cache-modules.19/

I only have one entry for Tsunami architecture compatible 1MB L2 cache modules although there are most definitely more out there (not that I know how they'd be marked). If you want to check a module with dubious markings you could count the pin groupings to determine if a module was physically compatible and maybe infer by the number of cache chips (and googling the chip markings) the total size. i.e. My 1MB card has 8 Micron 58LC32K32B2LG-10 128KB cache memory chips.

Everything I've seen says you should remove these motherboard L2 cache modules if you put in a G3 upgrade CPU card. That's not possible on at least the 9500 and 9600 (models that came with CPUs slower than 250MHz) which have 512KB L2 soldered onto the motherboard so I think some/all of the G3 upgrade card vendors found ways (perhaps not ideal?) to disable the motherboard L2 cache in software.

 

[XodiumRetro]

That's not possible on at least the 9500 and 9600 (models that came with CPUs slower than 250MHz) which have 512KB L2 soldered onto the motherboard so I think some/all of the G3 upgrade card vendors found ways (perhaps not ideal?) to disable the motherboard L2 cache in software.

Not sure if it's the same on other Tsunami boards, but I know on the 9600 there's actually a resistor on the board that can be desoldered to disable the onboard cache entirely.

Though at least for NewerTech cards, the drivers do dance around it effectively and remap the logic board L2 as L3 cache.