New batch of pdp8 OMNIBUS to USB interface! Please Read and react!

Philipp Hachtmann hachti at
Sun Feb 19 05:13:04 CST 2017

On 17.02.2017 17:55, Jon Elson wrote:
> On 02/17/2017 10:01 AM, Philipp Hachtmann wrote:
>>> The CPLD you had on the last board, XC9572XL is a bit long in the tooth,
>>> perhaps?   Would you expect to use that one again, or a newer chip?
>> I will use it again. It was already old when I decided to use it. It
>> has 5V tolerant inputs.
> It seems that Xilinx has made some hints that they do NOT plan to retire
> the XC95xxXL series any time soon.

> If they do, the CoolRunner II family can be used with the addition of
> one more voltage regulator.
By the way my handmade prototype with three CPLDs (I ordered the wrong 
pincount) had CoolRunner II.
I then switched to the old one because the IO voltage compatibility.
I was unsure if I could connect TTL IN(!!!)-puts to the pins without 
degrading the chip too much: TTL inputs go up to 5V when they are left 
floating. I was simply not sure if the CoolRunner pins are properly 
protected against that. So I chose the safe option.

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