The Mini PET 40/80 (2022)
a day ago
- #hardware-mod
- #retro-computing
- #commodore-pet
- The Mini PET 40/80 kit uses modern through-hole parts with a WDC W65C02S CPU.
- Compatible with most Commodore PET software (2001 series to 8032), featuring 32K RAM (max for PET).
- Lacks a 6545 CRTC, so some graphical demos won't run, but most other software will.
- Updated design includes 2K video RAM, supporting 40/80 character modes with a 74HC257 for dot clock selection.
- Character inversion is now hard-coded in the ROM, eliminating the need for a 74HC74.
- New DIP switches added for more video mode options.
- Firmware rewritten to handle 80-column mode with only 6 clock cycles per character.
- New power circuitry includes 4000 series logic at 9V for soft power on/off and column selection.
- Replaced 7805 and TIP29 regulators with modern 8-pin versions for better standby control.
- Added a second datasette connector, allowing simultaneous use of SD2PET and datasette drives.
- Four new function keys, soft power controls, full-size reset/NMI buttons, and a 40/80 mode switch.
- Mini PET BASIC 4.1, adapted from Commodore BASIC 4.0, includes extra commands, a file browser, self-test, and DOS Wedge.
- Built-in file browser for quick loading from SD2PET or disk drives.
- 80-column mode ideal for text adventures, programming, and business software.
- 40-column mode remains default for games like 'Attack of the PETSCII Robots' and remakes of 'Tut-Tut' and '3D Monster Maze'.
- Optional 2-pixel gap between lines in 80-column mode improves readability.