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Thread: Parity or Non-Parity 30 pin Simm Memory for a RSX?

  1. #1

    Default Parity or Non-Parity 30 pin Simm Memory for a RSX?

    I want to upgrade my newly acquired RSX to 8mb memory. Does it require parity or non-parity memory? Does it matter?

  2. #2
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    When it doubt, get the parity modules, all other things being equal. Used to be that the big difference between 386 PCs and Apple Macs was that Apple didn't use parity memory, while PCs did--unless they didn't.

  3. #3
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    Not sure if you're still looking, but as I recall, the RSX will take either 1 MB or 4 MB SIMMs, both must be identical, and apparently of the "9 chip" variety. I've got 8 megs extended in mine. I can't recall if it's parity or non-parity.
    I was also able to track down extra RAM for the onboard video via eBay from some electronics supplier in Israel (the appropriate Radio Shack kit has long since vanished from the public memory). I could take a picture of the ones I have if you like.

  4. #4

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    Quote Originally Posted by blackepyon View Post
    Not sure if you're still looking, but as I recall, the RSX will take either 1 MB or 4 MB SIMMs, both must be identical, and apparently of the "9 chip" variety. I've got 8 megs extended in mine. I can't recall if it's parity or non-parity.
    I was also able to track down extra RAM for the onboard video via eBay from some electronics supplier in Israel (the appropriate Radio Shack kit has long since vanished from the public memory). I could take a picture of the ones I have if you like.
    That would be awesome. I ordered 8mbs of memory from ebay. The RSX doesn't recognize it.

  5. #5
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    Did you run setuprsx after?

  6. #6

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    I didn't. I wasn't aware there was a Setuprsx program.

  7. #7
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    Here's pictures of the system RAM I have installed, video RAM upgrade (raises it to 512KB, allowing 256 colours within Windows 3.1 at 640x480 and 800x600, or 16 colours at 1024x76, the Math co-processor upgrade, and the modified floppy cable if you need to replace the original floppy.
    rsxdisks.zip has the utilities disk in it, which has both the setupRSX.com utility, and the Windows 3.1 video drivers (you need to use the Windows setup program to install them or change resolution/colour depth).
    http://www.mediafire.com/folder/jb58.../Tandy_1000RSX

    Feel free to ask me any other questions you may have

  8. #8

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    Aren't those 256k chips? I just ordered a set of KM44C256BP-7 110 chips from ebay.

  9. #9
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    They would be 256KB if every byte were only 4 bits long. Computer math is convoluted.

    The "256" refers to the number of words, which is listed as 262144 x 4. The chip only has 4 data lines (pins 1,2, 18, & 19), which means that you're reading/writing words of 4 bits at a time instead of 8, so divide the word count by 2, and you get 128KB if every byte were 8-bits long. Their listed memory density of that chip is "1048576 bits." Divide that by 8 and you get 131072 bytes, which of course is 128K. With those two DIP chips, and the two JIFs soldered onto the motherboard, you get a total of 1024-thousand 4-bit bytes of video RAM, but since we all define a "byte" as 8 bits, that only amounts to 512KB of video RAM.

    Datasheet here: https://www.datasheets360.com/pdf/-7303039259885408999

    To be honest, at the time I bought them, all I was concerned about was getting the exact DIP equivalent of the JIP chips soldered onto the board right below the sockets. The RSX manual says that they need to be 80ns fast-page DRAM, but I figured that matching the 70ns of the ones soldered onto the board would work just fine, and it does.

    A note for when they arrive: When I load Windows with the AcuMOS video drivers, it takes a really long time to load, but with Microsoft's basic 16-color VGA drivers, it's nice and fast. I could well have buggered something up with all the installing/uninstalling I've done over the years (probably due for a wipe anyways), but it does get there eventually. Let me know if you experience the same thing.

  10. #10

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    I installed the ram. Is there a way to test video ram?

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