I’ve been working on an update for the PETdisk firmware which includes a bootloader to make future firmware updates simple. Now you will be able to update the firmware directly from the SD card – just copy a file onto the micro-SD card, put it into the PETdisk, and power on the PETdisk. Once the device finds a firmware update, it will automatically reprogram itself with the new code. This will even allow people to hack around on the firmware and try out changes themselves, without a programming cable. New PETdisk orders will include this update. I have changed the microcontroller in the PETdisk from an ATMega8 to an ATMega168, which has twice the program memory (16k as opposed to 8k).
In addition to the bootloader, the firmware upgrade will add support for wildcards, so commands like
will now work.
Also the BASIC 4.0 DLOAD command is working, and I have fixed a bug which was preventing certain files with capital letters in the extension (“.PRG”) from loading properly.
It turns out that the serial programmer wasn’t working earlier because I was using it with a USB-Serial adapter, as I feared. However, when I dug out an old Sony laptop with a real serial port, it worked right away.
The PETdisk has most of the necessary connections for reprogramming brought out to the socket used by the SD card adapter, so it should be simple enough to connect a programmer to update the firmware. I will try this soon and let you know how it goes.
Also looking into AVR bootloaders so in the future the PETdisk firmware can be upgraded by just putting a file on the SD card.. watch for that also.
So far, no success in getting this simple DASA programmer to work.. Although I am using a USB-serial converter, which may be a problem. I will try again with a machine that has a true serial port.
Commodore PET enthusiasts out there might be interested in the PETdisk, which is a gadget I put together recently. It is a simple storage device for Commodore PETs which connects directly to the IEEE-488 port, and has a passthrough port so you can still connect other disk drives. Check it out at the PETdisk page.
For the PETdisk and other Atmel AVR projects, I normally use an STK500 programmer to program the microcontrollers, which works well – but I would like to try one of the simpler serial programmers to see how well they work. The immediate use of this would be to help those who already have a PETdisk to update their firmware when updates are available, but I am also generally interested in how simple the simplest possible serial programmer would be. I’ll let you know how it goes!
Welcome to bitfixer. Here I’ll talk about all sorts of electronic/tinkering projects, with an emphasis on repairing and building modern hardware for vintage computers. Hope you enjoy it.