Monday, 8 June 2015

pet microSD - Commodore Pet SD card disk drive

Update: The PET microSD is now available to buy, there are also some new versions for different models of PET.
This is a disk drive replacement for Commodore Pet range of computers, the 2001, 3000, 4000 and 8000 series.
Plug it into the IEEE-488 port of one of these machines and it will work as a standard Commodore disk drive, so all the standard BASIC commands such as LOAD "$",8 and SAVE "FILENAME",8 etc. will work. As will the BASIC 4.0 extensions such as DIRECTORY and DLOAD "MYFILE".
Unlike the petdisk clones I built previously, these boards are based on PetSD by Nils Eilers. This is a much better design that uses proper IEEE-488 bus drivers to connect to the Pet, so should co-exist happily with real Commodore disk drives.
The original PetSD was based on SD2IEC, a very popular disk drive replacement for the Commodore 64 and other computers with the 6 pin din IEC connector. This has a very stable code base, with good support for file and access types, and D64 disk images etc. Nils has forked the SD2IEC code to produce NODISKEMU, and that is the firmware that is running on the pet microSD. It is compatible with the original petSD firmware as well, but the new code is recommended. This firmware is still under development, and can be updated as new versions are released by placing the update files on a microSD card - no programmers are required. There are various new products soon to be available in the world of pet disk drives. Dave Stevenson has a useful comparison matrix.
There are various connection options. The standard version will plug into the back of a 2001 / 3000 / 4000 / 8000 series pet using the IEEE-4888 edge connector. Power is supplied from the datasette drive connector.
Alternatively, power can be supplied by clipping into a reservoir capacitor inside the pet, with the cable fed out next to the connector.
This gives a slightly neater appearance, and frees up the rear datasette port.
The standard edge connector version with either power connector is £50.
The 8032-SK and 8096-SK do not have the edge connector at the rear, so there is a version for them which fits internally. Inside, it's the same board as the 8032, but the edge connector is not externally accessible, it has extension cables connecting the edge connectors to GPIB IEEE-488 connectors on the rear.
The pet microSD can be installed via a riser board which has an edge connector at the top to allow the original rear panel cable to plug in.
The 8032-SK internal mount version is £60.
For those with multiple Pets, there is a version that can be used for either 8032-SK internal mounting, or with a different riser card, on the standard pet edge connector.
The multi connector kit is £70, and comes with both risers and both types of power connector.
Finally, the 8296, 8296D and some early 8032's have a 24 pin header connector on the board. Pet microSD can be supplied with a similar header to allow internal mounting in one of those machines, although this is currently untested.
The jumper on the side can be removed to make the SD card read only. The 6 pin header on the side allows connection of an FTDI or similar serial cable. Currently this is used for debug, but there are some interesting future plans for that.
Please contact me if you would like to order one of these.

I've now written a pet microSD user guide.

Update 2:
The new batch of pet microSD boards, in blue, also include a datasette power connector with passthrough.

Update 3 :
There are now some new versions for different models of PET, including internal mount. That link has buy it now buttons.