Commodore PET - SD card solutions
 

I thought I'd contribute a small write-up of the SD card adapters I've bought.

Initially, I ordered the SD2PET Future from tfw8b, with the SD card included with software on it. At the time of purchase in April 2022, it was £88. It's a well put together bit of kit, sufficiently well put together that you can't get into it (although as my brother used to say, there's no such thing as a sealed unit). It plugs into the IEEE port and picks up power from a cable that plugs into cassette port 1. That means that you have to use port 2 for your datasette, and as there's no pass-though IEEE port, you can't have another IEEE device connected at the same time. I have the Tynemouth ROM/RAM replacement board so I can have 32k and Basic v 4.0 on my 3016 with v 2.0 ROMs, so the DOS wedge works fine with both devices. In order to resolve the datasette port 2 issues, I bought a cable extender for the datasette port so it picks up power from datasette port 2 thus leaving port 1 free.

It all functions fine, but once I'd got my 4040 drive working thanks to help on here, I found the lack of IEEE pass-thru a bit of a limitation so I then bought the PET DISK Max v 2.0 kit from bitfixer. This was $58 including shipping in June 2022.

This needs at most about 15 minutes of soldering which even I could do. I'm not a fan of how it picks up 5v using a clip lead (off a 6520) so I'll look into a neater solution, but it works OK. The device has no cover so I will have to design one for my 3D printer so it's not as good looking as the SD2PET, but it has two big differences. First of all, it has an IEEE pass-thru port so I can plug in my 4040 at the same time as having the PET Disk MAX 2.0 active. The PET DISK MAX 2.0 is configured using a small text file on the SD card which is read at power on, so I have configured it to device 9 which means I can use both this and the 4040. The other difference is that it has wifi capability. The connection (SSID/password) is in the same text file as the deviceid and it allows other device ids to be created that are on remote servers. Bitfixer provide a connection to a server over the internet which has random files on it which change every time, but shows how this works. It's great loading a PET program and running it from a server half-way around the world. More practically, I spun up a Pi with lighttpd on it and have created directories on there that I can then connect to from my PET. I popped the Pi into a 3d printed PET to look good. Again, this works just fine, first time and can have up to 4 deviceids configured on the SD card for connection.

In summary, the SD2PET just work, looks professional and works well, although it's a little expensive by comparison. There are a few programs that struggle with this device due to the default of using datasette port 1 for power.

The PET DISK MAX 2.0 needs some simple soldering (but if I can do it, anyone can) and the IEEE pass thru capability and the ability to remotely connect to servers (internal to your network or external) is pretty awesome to watch and use. For the price, I prefer the PET DISK MAX 2.0.

Happy to answer any questions.

Colin.

Re: Commodore PET - SD card solutions
 

Thanks Colin - while it always feels better to 'Buy British', on the strength of your review it would seem that the PetDiskMax is both cheaper - even accounting for postage from the USA - and more fully featured. Going on what you now know I imagine you probably would have chosen the PetDiskMax in the first place, but therein lies the value of your summary - it helps anyone following to make a more informed first choice.

Did you notice the throwaway comment by 'GaryC' over on VCFED that he has made a Commodore disc substitute using an Arduino Mega and 'just wires'? I didn't get the impression that he has put it into the public arena. In theory you need some hardware level shifting between GPIB lines and any conventional data / control lines, and that is exactly the purpose of those awkward to get MC3446 buffer ICs.

Re: Commodore PET - SD card solutions
 

I did see the comment over there. If I get the time, I may go and ask if there's any more details.

Colin.

Re: Commodore PET - SD card solutions
 

You can certainly drive a GPIB bus with an ATMega processor and 'just wires' as long as there are already the pull-up resistors on the bus and there is not too much capacitance, the ATMega can tristate the pins when not driving the bus. I have one of the USB-GPIB interfaces that does this, but I have never tried it with more than one device at a time.

Roger