The Sinclair QL Forum

That's not needed on the 68881/2 as these chips can accept 8 and 16 bit data too, it's just a question of putting the correct signals in place on the chip so it knows how you are talking to it.

It was quite clever of Motorola to allow the FPU to be used as a peripheral as well, as it opens it's use ...

I can't see why LS wouldn't work in that design - all those logic gates are only driving one load each, so LS will easily handle that. Speed should be ok at that clock speed. If you use sockets, it would be easy enough to swap out chips if you needed to.

The main things to watch for are slew rate, propagaton delay and fanout

The LS devices will drive more devices than the standard HC, but there are a raft of variants. It does depend a little on what you are driving, and what if any are your speed restrictions. There is a Motorola tech arcticle for ...

According to the datasheet for the MC1377 - the power input needs to be nominally 12V, around 30ma available. There is an onboard regulator on the chip to drop this to 8.2V That would suggest that the power supply needs to be at least 10V (so if it's 12v or there abouts, that's fine). The 12V is ...

to get red/blue stripes like that in what should be solid red suggests video is taken from the output of the MC1377, and that is not operating correctly - possibly +12v supply is not working correctly?

I think it's pin 14, but my circuit diagram I printed is tiny..

the service manual and the user manual together have an awful lot of good info on the QEPIII - I found them on Dilwyn's site.

There is a full circuit diagram - all be it on several pages of the pdf. For proper programming and verifying - you need to be able to supply two programmable voltages - vcc ...

Programmable voltage control by software for VCC and programming voltages could be done like this:

http://www.fischl.de/dcdccontrol/

It would be even better if the range of devices could be extended to bigger EPROM devices and also maybe GAL's ?

It's remarkably similar to the QEP III in basic blocks - if slightly less elegant.

You have your programming voltage generator down near the 5v regulator - the switch mode ic. A 4066 analog switch to route programming voltages to pins, there is a 555 timer - perhaps for pulse generation.

a pair ...

I don't mind compiling it, if people are willing to provide a list of the discovered issues, and the necessary patches :-)

In all seriousness, I still keep looking at the Minerva code and the techniques used in the programming in some wonderment. I found DTACK grounded a good source of tips for ...