On 10/28/2015 10:45 AM, clipka wrote:
> Am 28.10.2015 um 08:56 schrieb Stephen:
>
>>> As an aside, Hackaday.io seems to be full of people building computers
>>> "from scratch", using only individual logic gates. One guy claimed to be
>>> building a computer from nothing but 7400s...
>>>
>>> ....until you realise that he means the members of the 7400 family that
>>> implement entire counters, encoders, decoders, latches, etc.
>
> Fair enough, as far as I'm concerned.
>
Not worth mentioning unless it was built only using NAND gates. Now that 
would be something. ;-)

>> I hope he has a big power supply and lots of fans.
>> In the mid 70's I built a digital clock out of TTL. It needed 25 amps at
>> 5 volts to drive the logic. A couple of years later I built one out of
>> CMOS and that would run for an hour on a PP3 battery. (It was mains
>> powered the battery was for backup.)
>
> I suspect the guy in question wouldn't be using classic TTL (where on
> Earth would you get those nowadays, anyway), but rather LS-TTL, cutting
> power consumption to 20%.
>

This was about 40 years ago* and I was limited to what I could borrow 
from the production line. :-)
 From what I can remember of the circuit. It was mostly shift registers 
and divide-by counters built from D type flip Flops. Ending up driving 
Nixie Tubes for the display. (I worked for Boroughs at the time and 
there were a few lying around.)

*
I did not invent my Tardis until a few years later. ;-)

> I for one wouldn't use 7400-family chips anyway, and instead go for a
> CPLD (or, more likely, a collection thereof). Makes it much easier to
> make minor design changes even after the circuitry has been wired.
>
>

How about a LM8560? Or if you want to push the boat out and spend USD 4
http://www.ecyberspaces.com/productsview.asp?id=3179


>> Funnily enough. His project reminded me of you. Did you not once write
>> programs in PostScript or Printer Command Language?
>
> PostScript is fun! Especially since it comes with high-resolution
> graphics output fully integrated ;)
>

That raises the question. If Pov will not contemplate using a GPU. How 
about using a printer to do some calculations? :-P

-- 

Regards
     Stephen

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