Apple ll mouse card PAL chip logic diagram

An interface for a serial PC mouse: https://maceffects.com/products/maceffects-bitmouse-serial-mouse-card-for-the-apple-ii

In post #3, Crusty wrote:

"So the next step is to see who has stock of 16R4 chip. and find some equipment to burn the fuses."

Uncle Bernie comments:

good luck finding a "virgin" PAL16R4 (or any other fuse link PAL for other projects). Beware that Chinese sellers on Alibaba who peddle these long obsolete parts often pull them out of electronics scrap, and so they are already programmed and useless.

I would go for GAL16V8 which you still can buy for $1.95 upwards from various vendors catering hobbyists, and the programmers for those are reasonabley cheap when you buy a used one (such as a GALEP-4), but make sure you get the software with it. GALs are very universal PLDs and based on EEPROM technology they can be erased and reprogrammed many times. So unlike fuse link PALs, you could use pulls / salvaged ones.

For a programmer able to program fuse link PROMs and which still works and is in calibration you are looking at $1000 and upwards. Oh, and the software probably only runs on DOS. And might require a "dongle" on a parallel printer port which is extinct on modern computers. But if you had one, you could buy a fuse link PAL16R4 from Anchor Electronics in Santa Clara for  $1.75 ea., according to their Y2022 price list.

- Uncle Bernie

I agree the Uncle Bernie on the GAL16V8, both the Atmel and Lattice versions are readily available and easily programmed using an inexpensive programmer like the Minipro TL866.  I've programmed quite a few of those.  They are often used as a substitute for the older PAL16R4 chips in designs because they are so similar. 

I also completely agree about any program-once chip from Chinese suppliers on places like Aliexpress...  The likelihood of getting one that has already been programmed and therefore useless is nearly 100%.  You might be able to find some new-old-stock PAL chips from specialty vendors like Uncle Bernie mentions.

Here's the pinouts for comparison...

PAL16R4.png

ATF16V8B.png

In most designs the GAL chips are almost a drop in replacement.

It just came to mind that a good place to start if you are interested in programming a GAL chip for a very similar application as this one is the Mike Willegal "SuperProto".  It uses a 6522 which is a similar parallel chip to the 6520 on the Apple Mouse Interface Card and it also uses a GAL22V10 which is a slighly larger PLD but similar to the 16V8.  The application of selecting the parallel chip and the ROM image selection should be very similar.  If you look at Mike's project on his web site he includes the code for the GAL.  It is pretty understandable source code although you will ned to figure out tools to compile code for whatever platform you use.  Unfortunately I'm not able to access the SuperProto pages on Mike's web site right now.  Maybe someone has a mirror online.  If not, I have an archive of his site that I made and I could supply the source code files if needed.

I think ReActive Micro is selling SuperProto cards either assembled or as a kit.  That might be a good place to start as far as designing a USB mouse card.  I think that one that used a USB mouse would be a lot more useful these days than older designs that use serial mice because those are no longer widely available like they were 15-20 years ago.  Even PS/2 mice are just not common anymore, although still available new.  I don't think serial mice are even made anymore.

There are a few USB modules/chips or microcontrollers like some of the Arduino models that can handle a USB mouse.  If you essentially built a parallel interface card that looked to the Apple II like the Apple Mouse Card does, with the Apple Mouse ROM code on it, and then wrote code for the microcontroller that read the mouse and outputted the right signals for the mouse events, it should theoretically work and a cheap USB wired or wireless mouse would appear to the Apple II as if it was a vintage Apple mouse.