SIPOD IEEE-488 Interface

  • The SIPOD is an IEC to IEEE-488 bus converter. It allows computers with an IEC port such as the Commodore VIC-20 and 64 to use IEEE-488 peripherals intended for PET/CBM computers. However, the SIPOD uses a Commodore PET/CBM computer as its intelligence! It effectively turns the PET into a giant INTERPOD.


    The SIPOD hardware is a simple cable that consists of only wires. One end of the cable connects to the IEC port of a computer such as the C64. The other end connects to the PET user port. The wiring is as follows:

    • IEC Port pin 3 (ATN) = User Port pins B (CA1), C (PA0)
    • IEC Port pin 5 (DATA) = User Port pins E (PA2), F (PA3), L (PA7)
    • IEC Port pin 4 (CLOCK) = User Port pins H (PA4), J (PA5), K (PA6)
    • IEC Port pin 2 (GND) = User Port pin N (GND, or any other User Port GND pin)
    • User Port pin M (CB2) connects directly to User Port pin 11 (GRAPHIC)

    See this photo and the same photo again with annotations.


    While the SIPOD software program is running on the PET, any IEEE-488 peripherals attached to the PET are made available to the IEC bus.

    Download (SIPODV3.ZIP)

    An interesting aspect of the software is that it was designed to run on BASIC versions 1 though 4. It contains its own implementations of the IEEE-488 and IEC protocols, along with conditional code to deal with the differences in these systems.


    Mick Bignell, who was an ICPUG member in the 1980’s, developed the SIPOD and sold it through his company, Microport Ltd. In addition to the Microport contact info shown while the program runs, the code contains the string (C) MG BIGNELL.

    Ken Ross, who maintained the ICPUG software library, preserved the SIPOD. If he had not posted the information and software, the SIPOD may have been lost. Sadly, Ken passed away in 2005. He was active in the Commodore community until his death.