SX 64 I/O board

Commodore SX 64 I/O Board

  • only two versions known (to me) 251106 Rev A and 251106 Rev 1, difference seems to be capacitor c9 that is missing in Rev 1.
  • contains the logic and two CIA’s that the SX uses to communicate to external equipment like drives, printers and modems (and internal drive)

Integrated Circuits

PCB Identifier Chip NumberRemarks Memory Location/bit
UA1 TMM2016PRAM$0000-$07FF
UA3ROM$E000-$FFFF
UA4ROM$C000-$DFFF
UB274LS04
UBC36522VIA 1 (I/O)$1800-$180F
UBC46502ACPU
UC274LS00
UD274LS42
UD374LS86
UD4
UDC56522VIA 2 (Disk)$1C00-$1C0F
UE274LS14
UE37406
UF2M54532P
ULN2064
UF37404
UF5GATE ARRAY
UG47407
UG574LS193
UH1592Video AMP
UH49602One Shot
UH574LS197
UJ1592Video AMP
UJ474LS86
UK4LM311Comparator

Schematics

Commodore SX 64 I/O Board Schematics 251107

Commodore SX 64 I/O Board Schematics 251107

Board Image

251106 REV A

251106 REV A

251106 REV 1

251106 REV 1

2 Responses to SX 64 I/O board

  1. Ken says:

    interesting about the C9 on the rev 1
    I just ran into that issue installing a switchless jiffydos board
    I think c= directly soldered it to the 556 on that version
    if you look at the 2 picks of UE3 v1 has a resistor soldered on as a afterthought and the other its on the board properly marked as C9

  2. Ken says:

    um my bad UE3 has a capacitor …not resistor
    shouldn’t try and type before my morning coffee

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