HP 16500A memory upgrade part 3

I’ve worked out the wiring of the SIMM to the CPU board. Unfortunately, the OE signal on the SIMM is hard-wired to ground, which is annoying. I’ll have to lift the legs (pin 16) of each of the RAM chips and hand-wire them together.

This is completely untested…

Signal 16500A chip pin SIMM signal SIMM pins
. GND all 20 VSS 1, 39, 72
. Vss all 10 VDD 10, 30, 59
. D0 U43, U52 19 DQ8, DQ24 26, 27
. D1 U43, U52 18 DQ7, DQ23 24, 25
. D2 U43, U52 2 DQ6, DQ22 22, 23
. D3 U43, U52 1 DQ5, DQ21 20, 21
. D4 U23, U34 2 DQ4, DQ20 8, 9
. D5 U23, U34 1 DQ3, DQ19 6, 7
. D6 U23, U34 19 DQ2, DQ18 4, 5
. D7 U23, U34 18 DQ1, DQ17 2, 3
. D8 U44, U53 2 DQ16, DQ32 65, 64
. D9 U44, U53 1 DQ15, DQ31 63, 62
. D10 U44, U53 18 DQ14, DQ30 61, 60
. D11 U44, U53 19 DQ13, DQ29 57, 58
. D12 U24, U35 19 DQ12, DQ28 55, 56
. D13 U24, U35 18 DQ11, DQ27 53, 54
. D14 U24, U35 1 DQ10, DQ26 51, 52
. D15 U24, U35 2 DQ9, DQ25 49, 50
. W0 U23, U34, U43, U52 3 nWE 47 (top half)
. W1 U24, U35, U44, U53 3 nWE 47 (bottom half)
. RAS all 4 RAS0, RAS2 44, 34
. CAS0 U23, U24, U52, U53 17 CAS3, CAS2 42, 41
. CAS1 U34, U35, U43, U44 17 CAS1, CAS0 43, 40
. OE all 16 wire separately
. A0 all 6 A0 12
. A1 all 7 A1 13
. A2 all 8 A2 14
. A3 all 9 A3 15
. A4 all 11 A4 16
. A5 all 12 A5 17
. A6 all 13 A6 18
. A7 all 14 A7 28
. A8 all 15 A8 31
. A9 all 5 A9 32
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One thought on “HP 16500A memory upgrade part 3

  1. Pingback: HP 16500A memory upgrade part 4 | martinjonestechnology

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