The Commodore IEEE-488 Cartridge for C64

Commodore 64 disk drives were usually connected through the slow serial bus. This article shows some hi-res photos of the Commodore “IEEE-488 cartridge”, which made the faster PET drives available for the C64.


The IEEE-488 cartridge is connected to the expansion port of the C64.

It has a pass-through expansion connector at the top, which allows using certain additional cartridges.

The IEEE-488 connector is on the side. This is the edge connector version, like on the PET.

If all you have is a standard IEEE-488 cable, you can use the adapter from RETRO Innovations.

The two main chips on the board (ASSY NO 250418 REV.A, P/N NO 250411 REV.B) are a MOS 6525A TPI (“Tri-Port Interface”) I/O controller with 24 GPIOs, and a 4 KB EPROM. The contents are available on

The back side reveals that the sockets of the four smaller chips of this cartridge have been added later by the user. U6 has probably been replaced: Originally, it should have been a MOS 7713 part.


These Commodore cartridges are rather rare these days, but
* There were several (historic) third party cartridges with the same functionality.
* DL2DW describes how to build your own.
* PolyPlay sells new cartridges.


The VICE emulator allows you to add the Commodore IEEE-488 cartridge to your configuration by attaching the EPROM as a cartridge image and hinting to VICE that it’s the IEEE cartridge. The UI will then let you attach disk drives like the CBM-8250 and the SFD-1001.

5 thoughts on “The Commodore IEEE-488 Cartridge for C64”

  1. I have the original IEEE card. My clip came out of the c64. Can you PLease, tell me where to attach the clip to in the mother board please.. you wouldn’t have any idea how much this would mean to me! I have the one that plugs into the back, and then the ribbon plugs into the 1541. And it’s a needle prong that attaches to the board. I just need to know which prong,inside of the computer, it attaches too ..please,

  2. Tommy, I’m making a big guess here but it may very well work out for you. I had a IEEE card also that I used on my C64 with an SFD 1001. Unfortunately they are long gone when I closed down my BBS. Doing a search I found this URL:
    This is for a BusCard II IEEE-488 Interface from Batteries Included. I would guess many of these manufacturers used a similar design and needed to get timing from a similar source. At his page there is a link to the Manual for the BucCard II. On page 6 (Page 1-2) under Installation it references clipping their wire to Resistor R44, “hook the clip under the resistor lead from front to back. The images they provide are a bit muddy so it gives a general idea of where to look for R44. It may be a risky adventure to try this but it’s all you’ve got. Good lick to you on this.



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