1MB cache

[Bunsen]

Does anyone actually have a 1MB cache for their 6100,7100 or 8100?

 

[Franklinstein]

I'm pretty sure that all of mine are either 256 or 512k, though there's a chance that my 8100/110 might have the 1MB (I'm not in a position where I could check to be sure).

As for fitting a larger one from a newer machine, I think they changed something on later models where the modules wouldn't physically fit in the older machines, so that's probably out... haven't tried before, tho.

 

[Quadraman]

I don't know that you would want 1 meg cache on those machines. I've seen benchmarks where 1 meg cache is actually slower than 256 or 512k.

 

[Unknown_K]

I have a 1MB cache stick in my 81/110 (not sure where I got it from, the machine originally had a 256K cache SIMM). Not sure if the machine is using it or not (software shows it installed).

 

[Mike Richardson]

I don't know that you would want 1 meg cache on those machines. I've seen benchmarks where 1 meg cache is actually slower than 256 or 512k.

I read somewhere that if you have a 1 MB cache and you use the onboard video, the video memory shifts from RAM to Cache, freeing up about 600 KB of RAM and speeding up the video. The remaining 400 KB or so of cache is still used as cache.

See http://lowendmac.com/benchmarks/6100.shtml

Adding 1 MB cache boost graphics performance 29% over no cache, 27% over 256K cache.

 

[tomlee59]

I don't know that you would want 1 meg cache on those machines. I've seen benchmarks where 1 meg cache is actually slower than 256 or 512k.

Perhaps you are thinking of the effect of the disk cache settings control panel? In that case, there is an optimal range. But that's different from a hardware cache module that does its thing invisibly. The disk cache setting involves the OS as an intermediate agent, which is why bigger is not always better in that case. But a hardware cache module? Bigger is better there.

 

[Bunsen]

If anyone can confirm that theirs is a 1MB cache, it would be great if you could upload a scan labelled as such to the Nubus Mafia. I am pondering the possibility of hacking 256MB SIMMs into 1MB SIMMs, and I want to have a closer look at the similarities and differences.

 

[Bunsen]

Or indeed making up something like a SIMMtree to mount four modules as one

 

[Bunsen]

I have a 1MB cache stick in my 81/110 (not sure where I got it from, the machine originally had a 256K cache SIMM). Not sure if the machine is using it or not (software shows it installed).

Unless you're also running a G3 PDS upgrade (which has its own cache) it should be using it

 

[trag]

If anyone can confirm that theirs is a 1MB cache, it would be great if you could upload a scan labelled as such to the Nubus Mafia. I am pondering the possibility of hacking 256MB SIMMs into 1MB SIMMs, and I want to have a closer look at the similarities and differences.

I have a 1MB cache somewhere. I don't know if I can lay my hands on it. It was from NewerTechnology. I bought it as a clearance item from some Mac equipment seller, years ago, turned out it was defective, and NewerTech replaced it. The original, defective one had a bunch of chips on board. The replacement clearly used higher capacity chips and fewer of them. So the original defective one would have been similar to what you're trying to do probably--build up smaller chips into a larger agglomerate.

One thing I do have which might be helpful for you is the pinout for the cache slot--sort of. As you may know, the cache slot and the ROM slot in the x100 machines are interchangeable, i.e. the ROM and Cache DIMMs may be installed in either slot without preference (except it's sometimes good to put the cache closer to the CPU). What you probably do not know is that the pinout of the ROM slot is the same as on the x500 series and on the Beige G3 series, with some minor differences. And I do have most of the pinout for the Beige G3 ROM slot. If you want it, email me at trag@io.com and I'll throw it up on the space I use for public files.

One difference is that the Beige uses pins, which are unused on the x500/x100, for the 3.3V supply, because its parts run on 3.3V whereas the older machines use chips which run on 5V.

It would still be a good idea to confirm the pinout but this will get you way more started than probing at random. I only identified the pinout needed for a ROM module. There may be other pins implemented in a cache module. Wouldn't there be something like a cache hit/cache miss signal back to the host?

BTW, OWC has bundles of those 256K caches for really low prices.

 

[Bunsen]

BTW, OWC has bundles of those 256K caches for really low prices.

Yeah I know. That's what got me started on the idea of hacking up a 1mb solution.
The market for this solution would be incredibly limited - the PDS G3 upgrades provide 1MB of cache and it would be only those who want to mount a Nubus card in a 6100 (ie me) who could use one of these.

 

[Bunsen]

As you may know, the cache slot and the ROM slot in the x100 machines are interchangeable, i.e. the ROM and Cache DIMMs may be installed in either slot without preference

No I did not know that

(except it's sometimes good to put the cache closer to the CPU). What you probably do not know is that the pinout of the ROM slot is the same as on the x500 series and on the Beige G3 series, with some minor differences. And I do have most of the pinout for the Beige G3 ROM slot. If you want it, email me at trag@io.com and I'll throw it up on the space I use for public files.

Please do. Do you suggest that a 1MB cache SIMM from a later model might be usable in an x100?

 

[trag]

Okay, the firmware module (ROM) pinout is up at http://www.io.com/~trag/Apple_pinouts/

No, I am not suggesting that the PowerSurge cache would work in the NuBus machines. I'm just saying that the ROM pinout is similar to the x100 cache pinout.

The Power Surge cache slot may (or may not) be a different animal entirely.

 

[MacTV]

I have a 1mb cache for my 6100.

When it was my main machine it made a WORLD of difference.

I also had an clock chipper on it - and while that helped - it didn't do nearly as much as the 1mb.

I never knew why it was so dramatic until recently - as the previous poster said it caches the entire video buffer.

 

[Bunsen]

MacTV - would you be able to upload a high quality scan of both sides of your cache to somewhere?

 

[MacTV]

I will be happy to do that.

A couple questions - what is the best software to verify the size of the cache - the Newer Ram Gauge thingy - or even Apple System profiler?

I'm not sure what OS is on the machine right now - dunno if Profiler is on there.

I've got two 6100s and I've swaped parts back and forth for various projects - I want to make sure I'm showing you the right one.

2nd question - it looks like you had a lot of 6100 projects going according to those Applefritter forum posts.

Did they come to fruition? Do you have any pictures?

 

[Bunsen]

Meh. They got put on semi permanent hiatus. The gear's all still here, and it looks like BunsenLabs will actually be up and running in the new year.

 

[trag]

I will be happy to do that.
A couple questions - what is the best software to verify the size of the cache - the Newer Ram Gauge thingy - or even Apple System profiler?

The Clockometer or Cache22 components of NewerTech's Gauge series will show you the L2 cache size, I think. I don't think that RAMometer tells cache size, but I may be misremembering.