Sinclair ZX80 questions
julesrichardsonuk at yahoo.co.uk
Tue Aug 22 02:30:55 CDT 2006
Tony Duell wrote:
>> Tony Duell wrote:
>>> I bought an MK14 back when it was current. That put me off Sinclair for
>> Out of interest, what was so bad about them that wasn't typical of that class
>> of machine around that time? Admittedly without having been involved at the
> Well, the keypad was terrible (I ended up soldering 20 switches from
> Maplin onto the MK14 PCB, the holes and traces were there for them...).
> There were some very marginal bits of logic design (hint : a '157 is a
> multiplexer, a '175 is a latch, but the MK14 uses the former as a the
> display output register. It works for _some_ makes of '157...). The CPU
> buses are not broungt off-board, so expansion was a pain.
Hmm, that is really surprising about the (lack of) expansion ability - I would
have thought it's one of the primary reasons in choosing a machine of that
class. I can't imagine doing something like in the ZX series (solder-pad edge
connector) would exactly have put the manufacturing cost up by much!
> And so on. I
> wish I'd saved a little more money and bought an Acorn System 1.
True - at least there was the ability there to re-use the CPU card and add a
eurocard lack later along with all the later System cards. Mind you, from
memory of Acorn ads they didn't really play up any future expansion ability -
I don't think Acorn saw it as a real selling point back then.
> Releated to this was a horrible bit of Torch design. As you may know,
> Torch sold an upgrade for the BBC micro which added an internal PCB
> containing a Z80 running CP/N (no, that's not one of my typos...). The
> Beeb power supply couldn't really supply that as well, so what you did
> was remove the Beeb PSU altogether, connected a cable to the power
> connections on the Beeb's mainboard, and run the whole thing off a PSU
> in the (Torch-supplied) disk drive unit.
You know, my prototype Torch Z80 disk unit has power out at the back; I can't
remember whether the production ones were like that or not. It had never
occurred to me that someone would want to power the machine from it!
In a way I'm surprised that the beeb PSU couldn't cope though - the current
draw can't be a lot worse than other various internal add-ons for the beeb.
I've certainly seen a lot of beebs running the Torch copro without any PSU mods.
A. Because it destroys the natural flow of conversation.
Q. What's wrong with top posting ?
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