Modern mass storage solution for Commodore PETs
A petSD is a modern mass storage solution for Commodore PETs with an
IEEE-488-bus. It can be used instead of and alongside vintage floppy
disk drives. The petSD makes file sharing between the PET and the PC easy
by using standard SD cards for storage.
Since the first petSD from 2011 (now obsolete),
a small family of successors emerged, varying in price and capabilities.
Dave Stevenson offers a nice
Dave Curran distributes his
microSD: a small and affordable device in a form-factor comparable to the
PETdisk but with a more
powerful controller running the NODISKEMU firmware (formerly sd2iec), offering real plug'n'play.
The petSD-duo will eventually
sit at the upper end of the range. I'm occasionally sharing pictures of the
development on flickr.
Between these in terms of price and capabilities lies the
The hardware is based on an Atmel AVR
microcontroller with 128 KB Flash and 16 KB RAM which connects
to the IEEE-488-bus using dedicated bus drivers
75161) to ensure proper
operation when multiple devices are connected.
A green LED indicates activity, a red one flashes on errors.
As an option, a battery-backed real-time-clock
is available, accessible from the CBM and allowing the usage of a current
time stamp when writing files to the SD-card.
The PCB offers multiple assembly variants:
Here, the petSD+ is mounted inside the Commodore and attaches to the
IEEE-488-bus with a ribbon cable plugged into pin headers. The device number
is set by two DIP switches in a range from 8-11, as seen on the 1541-II.
The petSD+ offers the option to use a "proper"
IEEE-488-connector to fix the cable with screws. A text LCD display
(4 x 20 characters), having the same dimensions as the petSD+ PCB,
can stack on top for a sandwich construction. A menu system is controlled
by three buttons (prev, next and select) to operate on
settings such as the device number.
NODISKEMU is a fork of
sd2iec by Ingo Korb (et al) with some modifications
and extensions by Nils Eilers.
The IEEE-488 bus routines were re-written from scratch for improved
reliability and higher speed.
Binaries are available as nightlies.
Release-versions currently don't exist.
In case you'd like to show Ingo Korb your gratitude, you might want to
have a look on his wish lists at
100% Open Source
Firmware, Hardware and all necessary tools to work on them are free
The firmware NODISKEMU
is licensed under GPL 2 only.
Schematics, the PCB layout (made with KiCad)
and the further documents required to build the hardware are licensed under
CC BY-SA 4.0.
petSD+ rev. 1
Alternatives you might want to consider
- pet microSD — plug'n'play petSD without LCD display
- Flyer Internet
Modem — internet modem and disk drive emulator
- PETdisk — cheap
and simple microSD card storage (status unknown)
- ZoomFloppy —
attach vintage floppy disk drives to your PC over USB
Thankfully Dave Stevenson is willing to offer them in one form or another, he even made a huge
website about the petSD/petSD+ including an Ordering Page.