Back in the time of the IEEE drive (PET era), IEEE drives used the 6530 RRIOT chip (ROM-RAM-I/O-Timer).  This is a masked programmed IC containing up to 15 bits of I/O, 1 KB of ROM and 64 bytes of RAM.  Each RRIOT chip in the Commodore produced contained specific code relevant to it's respective drive.  Unfortunately, these chips are no longer produced so when one of these drives chips fails, there are no available replacements.

Fortunately, the 6530 was commonly used on many different machines from a number of manufacturers.  For more information about the RRIOT chip, please read the following link: <<RRIOT Wiki>>

This daughtercard allows you to use any 6532 RIOT chip, as it bypasses the requirement of the custom code to reside within the RRIOT allowing you to put the specific code for your device in an EPROM that plugs into the board.  This board, with the drive specific code on the EPROM is a replacement equivalent to the 6530 RRIOT.  The design used here is based on the Ruud Baltissen schematics, and has been re-worked into a board physically compatible with the 8520lp and functionally equivalent to the original design.

Should you be using this IEEE daughter card on an SFD-1001, you will need one 40 pin socket added to bottom of the through pins to give it enough height to clear the ceramic capacitors as well as rotated 180 degrees opposite of the 8250LP installation (note the IC and silkscreen keyways), the drive cover still fits fine. The board was re-designed for using a 8K Eprom like a 2764 (rather than the old 2K 2716).  The contents will vary depending on what drive model number its being used in and the manufacturer of the 5.25 floppy drive that's installed.

Commodore produced various 6530s, for example the ones used in the KIM-1. This design cannot be used to replace these ones, it is only meant to replace the 6530 in the following drives:

- 2040
- 3040
- 4040
- 8050
- 8250
- 8250-LP
- SFD-1001

The board comes to you as shown, fully assembled without  EPROM or 6532.  Those two chips you need to supply yourself.  You will also need to source the appropriate code for your particular drive and create your own eprom for your application.