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VRAM SIMMs for Macintosh Display Card 4•8


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Hello,

 

I've recently acquired a Macintosh Display Card 4•8 as a companion for the 8•24GC in my IIfx.  Are the 64-pin 256k VRAM SIMMs for this card available anywhere, or are they basically unobtainium at this point?

 

Thanks,

Casey

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The VRAM used by the 4•8 card is the same as the LC and Quadra/Centris models used. The ones in this listing have “4•8 Display VRAM SIMM” printed on the silkscreen as an added bonus:

 

https://www.ebay.com/itm/Apple-Macintosh-256KB-68-pin-80ns-VRAM-Video-Memory-SIMM-Quadra-LC-475-630-0044-/142042841646
 

As a sidenote: the 64-pin SIMM slots on the 8•24 GC are not for VRAM and instead are SRAM used for GWORLD memory. If you’re looking to track these down I can find pictures of mine. 

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Outstanding! I had read somewhere that the 48 cards took special 64-pin SIMMs but a quick look confirms the slots are 68-pin.  Thank you!

 

I would appreciate some photos of your 8•24 GC SIMMs.  I can confirm that the regular IIfx RAM does not fit.  I'm not sure what advantage filling those slots would have outside of some specialized applications, but it would be cool to have the slots full.

 

Thank you!

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4 hours ago, Unknown_K said:

The Apple 8.24 GC uses IIfx RAM last time I checked.

LEM states they're the same spec, but this has not been true in my testing. Using SIMMs I know work in the IIfx in my 8•24 GC, I get either a death chime or no power at all. Works fine with the ones I have pics of above.

 

I've never found official specs for these, as Apple simply sold an upgrade kit and referred to them as an upgrade kit.

 

I got mine by searching for '64-pin simm' on ebay and buying ones that visually matched this layout (pictures of ebay 8•24 GCs with populated SIMMs seemed to have the same 4-horizontal-chip per side layout.) I got lucky on the third try, though bear in mind I never had a high enough resolution picture to determine any of the silkscreening. It should be easier with my pictures to reference.

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There are other 64 pin SIMMs out there like Amiga GVP RAM and some old one off PC that used them and they are all incompatible.

 

I was luck to find some SIMMs that work in my Supermac Thunder/24 on some old AVID Targa 2000 boards (2 SIMMS will max it out).

 

Its been a while since I looked into VRAM for Macs and I don't have the 8.24GC to mess around with.

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So, back to the 4.8...  I have a single 256k 100ns VRAM SIMM (670-0269).  I tried pairing that with a 512k SIMM I had lying around just to see if it would work (it doesn’t, as expected).  Can I pair the 100ns SIMM with a 256K 80ns SIMM, or does it need to be a matching pair?

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  • 4 weeks later...
Posted (edited)

I just ran Speedometer 4.02 on the upgraded 4-8 and got 0.300 on the 8-bit Quickdraw test with the 8-24GC driver disabled (the 4-8 is not an accelerated card).  With acceleration enabled on the GC, the score improved to 0.420 on the 4-8.  The same test run on the other monitor (connected to the GC) runs at 0.710 with acceleration enabled.  It looks like the NuBus block transfer does help.

 

Those values were indexed to a Quadra 605 if I remember correctly.  So, not great, but not terrible either. 

Edited by cofford
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