Monday, 25 May 2020

The Mini PET Pre-Order Open

You've had the Minstrel 2, the Minstrel 3 and the Minstrel 4th. Introducing the Minstrel 5 Mini PET.
It does what it says on the tin. It is a fully functional 6502 based computer, compatible with a Commodore PET 2001N-32 (3032/4032), but in a much smaller form factor, less than a quarter of the size and a tenth of the power consumption.
The connectors at the back are positioned the same, so it can be installed in a PET case as a replacement board.
There's a lot of space left inside, isn't there.
Or it can be used standalone with a composite video monitor as a complete PET, only this one doesn't take up as much bench space.
There is a full IEEE-488 port, a User port and one datasette port (with a header for a second port), and an onboard piezo buzzer as found on later PETs.
The external datasette port can be configured as drive 1 or 2, with the other available for connection of a second drive via a pin header inside the case.
A second board is used to extract 9V DC from the PETs internal power supply (suitable for 5 pin 2001 and later 9 pin power connectors).
Video is generated using the same dual port RAM video as the Minstrel 4th, it outputs 40x25 text as PAL or NTSC composite video or can drive PET 9" or 12" monitors if mounted in a PET case.
It is designed to act the same as 2001N PET technology, 40 column text/character graphics. It does not have the CRTC chip in later 12" monitor PETs.
The kit uses all new, currently in production parts, including WDC 65C02S CPU. The pinout of this is slightly different to the original 6502, so it does not support anything else which plugs into the 6502 socket (so the Super PET board, 64K board and even PET Diagnostics are not supported). IO uses the N variants of the W65C21N/22N, which are more compatible with the NMOS originals than the S variants. There is 32K of RAM, and there are one of eight blocks of 28K of ROM, giving a choice of BASIC 1/2/4 with support for chiclet or normal / graphics or the business keyboard.
Most early PET software was designed for the chiclet or normal/graphics keyboard (20 key keypad), so any titles which bypass the OS keyboard routines may not work correctly with the business keyboard (11 key keypad).
Although it is technically possible to support a VIC20/C64 keyboard via an alternate ROM, this is not recommended as many keys are missing or labelled differently. Seriously folks, please stop asking. I tried this years ago and it really doesn't work very well. You won't like it. Don't bother. 
This is available as a self assembly kit, with all through hole parts for easy assembly, and high quality turned pin sockets for all ICs.

The Mini PET is available to preorder now as two kit options:

Kit A

This is the stand alone unit with 73 key tact switch normal / graphics keyboard. This is powered by a 9V DC power supply (such as this one), and output is via a composite video jack.

Kit B

This is a replacement board that can fit in PET case, uses the PETs power supply, keyboard, monitor and internal datasette (if it had one). It can drive 9" or 12" monitors, there are separate connections for these as the have different signal polarity on some of the pins.
It comes with board to connect to PET power supply (5 pin or 9 pin) and a connector for an internal datasette (as drive ID 1 or 2).
This is a suitable replacement for 2001/2001N/30xx/40xx PET cases, also 80xx and 80xx-SK (although only as a 40 column machines).

SD2PET

The SD2PET SD card disk drive would be an ideal companion to either kit. Fast loading of PRG files of D64/D80/D82 disk image files from SD card.

The Mini PET is available to pre-order now from TFW8b, shipping in 3-4 weeks.

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