Cmod C2 CPLD?

[porcupine]

Has anybody looked at using this for address decoding, 816 bus demultiplexing, etc.?

https://store.digilentinc.com/cmod-c2-b ... ld-module/

Not super cheap, but DIP-type package, breadboardable, 40 pins, has the JTAG etc. bolted on, and once one proves out the design one could use the SMT chip form instead. Would replace a handful of 74 series chips and allow the design to be worked out in the Xilinix tool, etc.

3.3v tho.

Curious if the 64 macrocells would be enough?

[BigDumbDinosaur]

porcupine wrote:

Curious if the 64 macrocells would be enough?

Depends on what is to be accomplished. My POC V2 units use about half of the available logic resources in an Microchip (Atmel) ATF1504AS CPLD, which has 64 macrocells. I'm actually constrained by the number of available I/Os (32 on a PLCC44 package). not the logic resources.

[porcupine]

At a minimum it'd be 816 data bus demultiplexing stuff + address decoder. Chip has I believe, 33 I/Os (XC2C64A VQ44). So about the same as yours. More pins would surely be nice. Too bad they don't make a 48 or even 64-pin version of this. The next thing up from them in this vein are two 48-pins that host full FPGAs. Useful but overkill, and $60-$75.

Life really would be much easier if WDC just made a 816 in a PDIP 48 package (or various SMT forms) with the extra 8 address lines broken out.

[LIV2]

I've been using the Altera EPM7064S which is 64 macrocells and supports 5V but like BDD the biggest problem is lack of pins.
I am using one as the address decoder for my 65C02 based system which only ends up using about 11 macrocells. I also managed to fit a basic VGA controller in one too.

I should get around to making a 600-mil dip breakout for it though. I've been using these breakout boards but they're wider than a 600-mil dip package and having both the TQFP footprint and traces on one side + the QFN ones on the other it's probably not great for high speed stuff. I should get around to making a breakout like the digilent one linked.

[porcupine]

Well, just ordered a couple of these. I'll see what I can do with them, at least to prototype on breadboard. Once I'm more confident with them maybe I'd just try my hand at SMT soldering and get something with more pins.

[LIV2]

Nice, are you building 3V systems?

Also what programmer are you going to use?

[porcupine]

So I was _thinking_ of attempting a 3v system. But it appears that I'm doomed really on account of the fact that there seems to be no through-hole EPROM or NVRAM type chips with a parallel interface and 3v supply voltage.

So now it looks like I've ordered this 3v only CPLD module but won't really be able to use it with a 65816 without coming up with some sort of SMT solution. Or doing level conversion between the CPLD and the system.

[Martin A]

You can get 3 volt SST39LF040 flash in PLCC format, that's reasonably through hole friendly.

[porcupine]

Cool. Tho PLCC isn't breadboard friendly.

[Dr Jefyll]

Technological Arts (and others) offer adapters like this...

[porcupine]

Cool. I see the SST39VF010-70-4C-NHE at Mouser, 128KB, 70ns access time, and cheap.

But what does one use for a programmer for such PLCC flash chips?

My EPROM programmer was destroyed in a flood last year, so need to replace it.

[Dr Jefyll]

This may sound like an odd question, but are you sure your EPROM programmer needs replacement? You might be in for a pleasant surprise, as I was after a freak rainstorm flooded my (and many other) basements in 2002.

A lot of my electronic gear, including audio and musical equipment, got entirely submerged. But at least half of it turned out to be OK, after simply having had a chance to dry out. Good thing I didn't just assume the worst and send the stuff to the landfill.

YMMV, depending on what sort of water is involved. I was comparatively lucky; rainwater is probably as benign as it gets. But in any case the takeaway is, don't just assume the stuff is pooched.

[porcupine]

The insurance settlement was such that anything that I was to be compensated for, they had to take away to discard. So it was either keep it and risk it not working again and not getting anything, or get compensated and go buy a new one.

That thing always annoyed me because it didn't work with GALs or CPLDs or anything, and the programming software was windows only. Cheap Chinese thing.

For what it's worth stuff I knew I couldn't replace (vintage computers, synthesizers) I kept and tried to repair. My amazing coworker just fixed two C64s of mine that were damaged in the flood. Some stuff worked just fine after, stuff I would never have thought would work.

The water was clean, it was a broken water softener, so just my well water. Most things came out ok, with a little corrosion.

[GARTHWILSON]

In many cases, PCBs are washed with water after the parts are soldered on in production. I have kept our company from using water-soluble fluxes because of problems these fluxes can cause in sensitive analog circuits. The water itself does not hurt the components though.

[Martin A]

There's cheap PLCC32 to DIP32 adaptors on e-bay and other places. Then you can program in a regular programmer as if it was a DIP version. The sockets on them may not take too many insertions and removals, but given how inexpensive they are, it may not be an issue.