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Thread: Apple IIgs 8MB RAM problem

  1. #11

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    Quote Originally Posted by Eudimorphodon View Post
    I have the GGlabs 4MB card that takes a single 30 pin SIMM and, knock on wood, I haven't seen any problems with it. But a 4MB 30 pin SIMM is *almost* directly electrically compatible with the GS's RAM slot so there's significantly less to need to get right than there is with an 8MB card. (The IIgs was really designed to support only 4MB, 8MB cards require some logic tricksiness to synthesize a D22 address line. Presumably that's what GGlabs isn't getting quite right.)
    The funny thing is, it *appears* to work fine in my ROM1 box. But the ROM3 box crashes within 10 seconds.

    I was thinking maybe since the ROM3 boards have more built-in ram, the card was shadowing some of the system ram and they were glitching each other out or something, I dunno.....
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  2. #12
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    From my understanding the IIgs as built can do 8MB of ROM and 8MB of RAM. The first 4MB of RAM uses build in DMA and refresh from the RAM controller, any RAM over that does not use DMA and you need to add chips to refresh it (engineering required). ROM 1 machines have 256KB of RAM on the motherboard, ROM 3 have 1.25MB on the motherboard. So on a ROM 3 machine when you attach an 8MB RAM card some of it is unusable and generally the RAM that falls outside of DMA is best used for s RAM Disk.

    A ROM 3 with the Apple 1MB RAM card is pretty much good for anything outside of GS/OS 6 and GS/OS is only nice to use if you have an accelerator (and 4MB RAM).
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  3. #13

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    Quote Originally Posted by george View Post
    Did you get a refund for the buggy GGLABS card? Their apple2 SCSI card appears to be buggy too. Shame for GGLABS "Designed and assembled in USA with all new components." advertisement in ebay, obviously the latter is not a key to error free and working products. Their publications full of colorful fancy screen captures from expensive state-of-the-art oscilloscopes/analyzers and technical explanations for the dazzled impressed breathless public But with the 8M //GS RAM card the well known superior German quality wins.
    I haven't contacted them about that. I bought it nearly two years ago and used it with a ROM 1 system without the TWGS or CFFA3000 and didn't have any problems, then put the old IIgs away. Then I got a ROM 3 board and installed it along with the TWGS, CFFA3000, and GGLABs card and installed GS/OS. I had the lockups and then ran the diags. As I'm relatively new to the IIgs before I started tearing everything apart I thought I'd check here first.

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