[sdiy] Digital topics like PLDs?

Rainer Buchty rainer at buchty.net
Mon May 25 14:51:15 CEST 2015


On Mon, 25 May 2015, Roman Sowa wrote:

> PLDs draw a lot of current, 100mA is not uncommon.

Depends. There's also the Coolrunner line of CPLDs.

> Another option would be to put a little OTP EPROM.

If speed allows. EPROMs often enough have access times of 70ns and more, 
which might be ok in case you're replacing some levels of standard TTL, 
but where originally 74F where used, even a fast EPROM might already be 
too slow.

For the DIL lovers, you may have a look into the GOP/GODIL like of 
products

 	http://oho-elektronik.de/index.php?c=1&s=product1

which offer CPLDs and FPGAs with DIL and, probably even more 
interestingly when it comes to vintage-gear interfacing, 5V-compatible 
I/O.

You can either build them yourself using the provided schematics or 
order them via Trenz Electronic:

 	http://www.trenz-electronic.de/products/fpga-boards/oho-elektronik.html

It's a pity that these days even small logic problems require the use of 
somewhat large-ish CPLDs or even FPGAs plus level shifters where 
what's really needed basically fits into a 22V10.

But the PAL route seems somewhat dead also from the design-software side 
of things (with PALAM1.5 plus PALTOGAL.EXE being among the last working 
alternatives).

Rainer




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