Thanks a lot for the kind words.

You may be able to use a FTDI USB chip if you already have one and skip the official programmer. There is a schematic here https://www.hackup.net/2020/01/erasing-and-programming-the-atf1504-cpld/ that I have not personally tested yet.

The programmer is basically ...

I'm regularly using my phone to browse the forum, with Firefox on iOS. It's a bearable experience, but yeah the text is tiny.

One super annoying thing, though, is I keep getting logged out, presumably as I move across cell towers and my IP changes?

Dataman S4 - as far as that's concerned it's "just another GAL" and will fit in the same adapter module.

Not really "hobbyist-level", at a few hundred euros, with only two available on eBay :mrgreen:

There's also an open-source GAL programmer based on an Arduino which lists support for the ...

I'm not aware of any hobbyist-level programmer able to program the ATF750s, what are you using?

What do you use to program the ATF750CL?

Can you implement a transparent latch with a GAL? I thought they only had D flip flops and you had to upgrade to a CPLDs to do that

No idea, actually! Wouldn't make sense for it to be a buffer, though, since the buffer is the '245

Really the circuit shown in the datasheet for demultiplexing the bank address is all you need, unless you want to use BE or RDY. For the latter I go into it in more detail in episodes 3, 5 and 6 of my YouTube series.

Why would a bank address of 0 be safer than any other value during power up?

Also, a 273 is not recommended because it is a D flip flop, meaning the bank address only appears after the clock rising edge. You want a transparent latch so the bank address is already present, and the select logic has ...

You don't need to reset the latch, as the cpu goes through a few internal cycles before accessing the reset vector and starting the program execution. Even though the latch powers up in an undefined state, its value will become known during the first internal clock cycle.

Sounds like a reasonable plan! Good luck with your project

You can look at what the CPU does for all cycles of every instruction in the datasheet starting at page 36 (Instruction Operation). I haven't tested it in hardware, but based on that table I don't believe a case where RWB, VDA and VPA are all low simultaneously exists.

There is no need to insert ...

Indeed - the PC is 16 bits and only increments within that. The bank byte is independent.

Thanks for confirming!

having a multi-byte Instruction like COP split at the edge of a bank seems like a pretty rare scenario. unless the program is specifically written to make use of the PC wrapping ...

I've been working on getting the COP signature byte, no use case in mind just a fun challenge. Here is the code I came up with in emulation mode and in native mode.
I don't have the hardware to test it with me yet, which makes me think I need to work on an emulator for the project! I'll report back ...

This is great, thanks for sharing!