newbie building a scratch-built computer
classiccmp at memory-alpha.org.uk
Fri Aug 10 23:31:49 CDT 2007
>> Good point, and the exact reason I picked up a "Softy S3"
>>about 10 years back (which is in SERIOUS need of TLC
> I rememebr seeing the adverts for that -- and drooling :-).
It is a *SERIOUSLY* useful device....it'll even emulate RAM, which is
surprisingly useful when debugging code. :-)
>....Alas I was an undergraduate at the time, and no way could
>I afford one, so I built my own programmer/emulator....
I first came across the S3 in '89, it was standard equipment at the company
I was working for at the time. It's one of the few times that I have been
genuinely blown away by a piece of technology. A sort of "Eureka" moment.
Even then I couldn't afford (well, justify) the cost of getting one to use
at home. In the end I picked this one up in '97, from the small ads of the
local paper, for £35!
It had been dropped, so the case is pretty badly damaged, but other than
needing an new Ni-Cad battery pack it's fully functional. Or at least it
was, I seriously need to overhaul it.
The irony is, I'm pretty sure this unit is one of the very ones I used
between '89 and '91. The guy I got it from bought it at a "clearout" sale at
Aston Science Park in '91....which was when the aforementioned company I'd
been working for, on said science park, closed down.... :-)
>....3 large boards of TTL chips (I couldn't use a processor,
>what could I have programmed the firmware with :-)).
LOL, good point.
I actually built my first EPROM burner from scratch too (though I never
built an EPROM emulator). I had little choice, as an Atari user my options
for off the shelf programmers were very limited - most connected via RS232,
no use to me as I didn't have the 850 serial/printer interface module. And
the only other one I remember would only work in an Atari 800 as it plugged
into the right hand cartridge port (I, of course, had a 400).
So I threw together a very simple design which connected to the machine via
it's joystick ports. The joystick ports were connected to a 6520 PIA inside
the machine which gave me two 8 bit I/O ports to play with.
Used one port to pass the data to be burned, and used the other to provide
assorted control signals - like the programming pulse, clocking/resetting a
pair of 4040 counters which provided the address to the EPROM (I said it was
Worked surprisingly reliably.
> I do have the original Softy somwhere. SC/MP based, TV output,
>programs 2708s. I can't rememebr if it emulatrs as well.
I've never actually seen one of those for real, just pictures.
Is it just me, or did they use a very similar case to that of the ZX-80?
Certainly, the bottom part of the case looks identical in the pictures I've
TTFN - Pete.
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