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  • Posts

    • The boards need to be 1.27mm thick.   The original spec. is for .050", which is 1.27mm.  There's some +/- in that spec, but really not enough to go to 1.2 or up to 1.6.   1.6mm is .063" thick board, which is far thicker than .050".  I'm amazed that you could get it into the socket at all.   I posted some datasheets for SIMM sockets in an old thread, which included the specs for boards that fit into the sockets.  
    • AFAIK, the only Quadras that could go over 136 were the Q605 variants and the Q63X version that had two SIMM sockets (636?).     The C/Q 610/650/800 all have, as shipped, limits of 136 MB.  As it turned, as mentioned in my previous post, that was a limitation of the firmware and how memory was detected at boot time, not a limit of the memory controller hardware.   Apparently, the firmware didn't check the higher Row (or column?) address lines that are needed when larger capacity memory is installed.   Let's see, a 16MB bank in 72 pin memory is 4M addresses X 32 bits (4 bytes).   4M addresses is represented in 22 bits.   A 64MB bank in 72 pin memory is 16M addresses X 32 bits (4 bytes).   16M addresses is represented in 24 bits.   The address is "multiplexed" (split up) as ROW and Column addresses.   The 30 pin and the 72 pin SIMMs support a maximum of 12 address pins/signals.    So, as you can see, 16M addresses is the maximum possible (12 + 12 = 24 bits => 16M addresses), and a single bank of memory, which is 4 bytes wide, cannot be larger than 64MB (16M X 4bytes).     Anyway, a 16M bank can be 10 X 12, 11 X 11 or 12 X 10, in theory.   A 64 MB bank must be 12 X 12.     The Quadras were seeing 64MB SIMMs as 16MB, because they were ignoring a couple of the address bits. 
    • Actually, the Quadra 610 and 650 did have a pretty hard 136 MB limit on RAM, even when larger modules were installed, until bbraun (or was it Doug, darn, now it's been too long) dug into the firmware a bit and changed some boot parameters so that the memory controller was allowed to "see" more memory.   There was a thread on it around here before the system change.  I hope its still around.   IIRC, he took the 650/800 up to 512MB or thereabouts.  Part of that may have been forced into a RAM Disk.    On the SE/30, each bank of four 30 pin SIMMs is the equivalent of one, single bank, 72 pin SIMM.    If you built the machine with two 72 pin SIMM sockets, they'd be limited to 16MB or 64MB SIMMs.     32 MB 72 pin SIMMs are not going to work in such an adaptation, because almost all the 32 MB SIMMs in existence are 2 bank SIMMs.  They're made out of two separate banks of 16 MB.  Banks are controlled by having independently controlled RAS lines.  There's no reason to believe that the there are any more than two sets of RAS lines in SE/30.     One possibility would be to modify the board for a single 72 pin socket.  Combine the signals for the two SE/30 memory banks onto a single 72 pin Socket, which would support one or two banks.    That way, one could install a single 16, 32, 64 or 128 MB SIMM and it would work.   If you go with two sockets, then the only way to get 128MB would be with two separate 64MB SIMMs and again, 32 MB SIMMs would not work, or would only be seen as 16 MB.
    • I replied without reading it carefully, but what you are talking about is adjustment in York.
      And in the case of my CRT, the convergence went awry, so I couldn't adjust the yoke unless I turned it about 180 degrees. You can see that the convergence is out of order in the previous images...Convergence is now adjusted.
      I was mistaken for the variable width range. But thx for advice!
    • Also bumping the inner/outer copper on the board might help get a better fit. 
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