The Ulti-PET
(C) 2022-2024 André Fachat
The Ulti-PET is a re-incarnation of the Commodore PET computer(s) from the later 1970s. It is currently build on a multiple Eurocard board and has only parts that can still be obtained new in 2021-2023. It is re-using various technologies from the Micro-PET, the CS/A computer, and others. Currently it is a work-in-progress.
The goal is to combine multiple of these boards into a single PCB that fits a (slightly modified) C64 case. This board is currently in the design phase.
Note that I now call it "Ulti-PET" to avoid confusion with Gideon's Ultimate projects.
After building the Micro-PET I noticed, that for further features, I would have to get larger than a Euro-card. The challenge - for me at least - is that I use an older, private-use restricted version of Eagle that can only do Euro-card PCBs, but not larger.
So, the current version is based on multiple Euro-PCBs, but will eventually be combined into a single PCB.
The main development is happening on github (see link left in the menu).
Features
Here is a list of the features. Most of them have been implemented in the Eurocard version already, and only need to be combined into the single PCB:- Ulti-PET features
- Commodore 3032 / 4032 / 8032 / 8296 with options menu to select at boot
- Boot-menu to select different PET versions to run
- 40 col character display
- 80 col character display
- 8296 memory map emulation
- IEEE488 interface (via PETIO board)
- Tape connector (pin, via PETIO board)
- PET graphics keyboard, or alternatively a C64 keyboard
- Improved system design:
- 512k video RAM, 512k fast RAM accessible using banks on the W65816 CPU
- boot from an SPI Flash ROM
- up to 12.5 MHz mode (via configuration register)
- VGA Colour video output (RGBI in 640x480)
- Write protection for the PET ROMs once copied to RAM
- lower 32k RAM mappable from all of the 512k fast RAM
- Improved Video output:
- Multiple colour modes (Colour-PET, C128-VDC-compatible, Multicolour)
- Colour Hires graphics mode
- Modifyable character set
- 40/80 column display switchable
- 25/50 rows display switch
- multiple video pages mappable to $8000 video mem address
- Audio output:
- DMA engine to play audio samples on stereo DAC sound output
- Dual-SID
- Extra I/O features on top
- Colour-PET compatibility (as defined by Steve Gray's colour-PET project)
- RS232 interface
- Fast serial IEC bus (like in the C128)
- Both IEEE488 and IEC bus are capable of being used as device for another computer (ATNA capability)
- An extra 8-bit I/O port in addition to the Userport
- Simpler and more versatile system bus (using the Ultra-BUS backplane:
- CS/A bus (my standard)
- Some Apple-II bus compatibility
- RC2014 bus connectors
- Extensions planned on the combined board:
- (Built-in disk drive simulator (e.g. nano488 or pico488) - Cancelled due to space restrictions
- Built-in Userport extensions, like Joystick ports
As mentioned, the current design uses multiple PCBs, esp. the Ultra-CPU and the Ultra-Bus. The Ultra-CPU, Ultra-Bus and the existing CS/A PETIO board already make up a Colour-PET clone.
Some pictures of the current state of the Ultra-PET
Return to Homepage
Last modified: 2024-02-03