Interestingly that's more or less what I have got

I have added a fourth 'ATN' line. and got drivers in between.

Thanks Garth. That's the reply I was hoping for.

I'm guessing the 6522 problem you are referring to is the shift register with external clock on CB1. I know about that ( I used to work for Commodore in the 70s and we had a dealer try to build a network using the 6522).

Are you suggesting that if I ...

I have just got a small 6522 board running at 4Mhz and I now want to up the clock rate to 14MHz (well I am planning to use a 14.318MHz Oscillator).
I have added a wait state for EPROM and I am using 15nS static RAM. When I read the W65C22S data sheet there is a timing parameter called tACR which is ...

I helped with a wait-state generator using the 16V8 a few years back. The info is on my website, including winCUPL source. You can find it here -> http://sbc.rictor.org/wsgen.html

Daryl
I have just been trying this. As I only require 1 wait-state I entered the following:
FF.d = !rom & !FF ...

From where did you get those GALs?

Various sources: ATF16V8Cs, ATF22V10 from Mouser. (unable to program)

Lattice 16V8D-15 Ebay ... UK Source.

Atmel 16V8Bs from Ebay. Can program

Just ordered some Lattice 22V10-7s on Ebay from Israel.

It looks like my mod caused the 2V problem, I had 2 ...

I helped with a wait-state generator using the 16V8 a few years back. The info is on my website, including winCUPL source. You can find it here -> http://sbc.rictor.org/wsgen.html

Daryl

Thank you Daryl. I have seen your posts but didn't come across the link before. I'll give that a try ...

OK thanks for that but that bit compiles ok.

I am not using pin 11 so I can ground that.

The problem I am getting is at compile time with the ready.d line:

ready.d = !(ready.dq & rom);

i've tried different extensions for the feedback term but all of them produce a compiler error.

The error ...

Well, I bought it about a month ago from a website called semikart (I think they are essentially a proxy for mouser in india). The part numbers on the chips are:
1) W65C02S6TPG-14
2) W65C51N6TPG-14
Thanks!


be careful of the W65c51, as you will see elsewhere on this forum there are some big ...

I have been reading the posts elsewhere on here about inserting wait states and I also found an old Apple I manual with a wait state using a D flop and a nand gate - WAIT - Schematic.pdf .

I have tried to implement this usng a 16v8 GAL using WinCUPL - wait.txt

I keep getting errors when I use ...

As it turned out I could only get parts in PQFP or TSSOP, so i have ordered everything from mouser, i went for the duart as I can re-use it when I get past the debug on this board. Ordered some proto PCBs as well so should be able to build in about a weeks time. I'll keep you posted, in the meantime ...

Thank you for posting this topic, I have tried to find SC28L91s. My local stockist only has the '92s and no longer stock the '91s. Looking through the datasheet it appears that both parts have the same pinout but the RxDB, and TxDB pins have been removed on the '91. I have pulled a design together ...

Having read this post further I have decided to switch to the SC28L92 or SC26C92 DUARTs. which are 44pin PLCC unfortunately, but fast (10nS for SC28L92) WRb. Will take a closer look at the datasheet but really impressed with the content of this thread, so useful.
I am currently using the 28L92 in ...

Part of my reason for looking for an old keyboard is that the good ones were mechanical and had a really satisfying feel. Most modern keyboards aren't nearly as satisfying to type on unless you spend a fortune. I already have TI 99/4a and it's keyboard is particularly nice, although a bit small ...

Having read this post further I have decided to switch to the SC28L92 or SC26C92 DUARTs. which are 44pin PLCC unfortunately, but fast (10nS for SC28L92) WRb. Will take a closer look at the datasheet but really impressed with the content of this thread, so useful.

Thanks, I kind of guessed that would be the case, all though I'm pretty upset with WDC for continuing to ship pretty useless parts. Especially as they cost me £7 each.

I have already put the code together to use a 6522 timer which works for one board but I don't have a spare timer.

I'm working at ...