XC9572 breakout

Frank and I have been working on reverse engineering and fixing/finishing these cheap S100 PCBs I bought off of ebay. These are “DOUBLER” floppy controller and serial controller cards. The first thing I did was scan the blank PCB I got and post it on the internet archive if anyone wants to make a schematic or replica board. This is version 14, as indicated in the copper layer. The only ones I can find documentation for are up to version 2… so what even is this? That will come later, hopefully, but as we read the schematics that are available and trace our PCB we have been putting together what the PROMs on this board should contain. We haven’t done it for the disk controller stuff yet, but we have done it for the serial controller portion. Now, how do we burn PROMs? well, we could try to get original devices and get a programmer for them but that sounds expensive and hard. We decided to go with a CPLD. This one isn’t too old and still supports 5v logic levels. But using this package dead bug is a pain.


That’s not super ideal. And programming it…

That’s some 30ga wire to a protoboard with some pin header on it that we can plug in a knock off usb programmer into. That is not ideal. So what did I do? breakout board!

look at the Rossmann level of flux shine!

I have here a programmer that I modified to supply 5v to the target hooked up to the new breakout and it works great. Let’s look at the design:

Here is the programming header, already wired up to the relevant pins so I can just plug in my programmer. I have pins as breakouts for power, ground, and IO power. I also have a jumper to connect IO power to core power. This chip can run the IO at a lower voltage that the internal logic, or you can run both at 5v. on mine I jumper it for 5v on both, but I left a jumper so these could be more general use boards.

You can see I completely punted on the pinout. I just wanted something easy for me to hand wire. If I need to build this into a project, I’ll spin another design for that, but I prioritized readability of pin names over positioning because I didn’t want to have to resort to the documentation for how I laid out the pins. They’re all there, they’re all labeled, just use it. The files are here for anyone who also needs a solution for older bipolar PROMs. Hopefully there will be follow ups with the setting up of the toolchain in a VM and the fixing of the doubler card.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: