> > I can understand why the Apple ][ has a significant following - it was a
> > machine that was 'open', that hackers could get inside, etc. But I also
> > know that it's not a good piece of hardware design, and thus don't put it
> > high up my list of interesting machines.
>
> It depends on how you define "good". Wozniak clearly had a different
> definition - he would fret for days about reducing chip count by
> using some clever scheme. From the hardware manufacturer's point
> of view, a couple dozen assembly language instructions are free, while
> chips (and board space) costs real money.
Yes, but it some cases the 'kludges' led to problems later on - 'trivial'
problems like a total incompatability between the Disk II and just about
any other machine in the world, 'mariginal behaviour' like a case that
overheated, a PSU that was beyond the design limit when running a system
board, language card and 1 drive, things like that that caused some
machines to crash after about 1 hour, that _crazy_ slot addressing scheme
and the saving on chips/PSU consumption by switching the power line to
the I/O card ROM - I may be old-fashioned, but I don't like driving input
pins past the supply rails..., etc
Saving components is only 'good' when it doesn't affect performance. I am
not convinced that this is the case with the Apple ][
Oh, please don't think I am picking on Apple. The PERQ (my favourite
machine) has a number of _very_ marginal timings. The various CPU board
clocks are delayed with respect to each other by a string of TTL inverters
and buffers. Some memory cards will only work in landscape mode - the
timing is 'on the edge', so that the portrait mode doesn't work. And for
those that do work in portrait mode as well you often have to change a
coupld of chips to slower versions (say a 74S157 -> 74LS157) to get it to
work correctly.
> Wozniak's attempts to reduce chip count aren't very different than
> the efforts that radio manufacturers have made to reduce tube counts.
> Almost all consumer-grade superhets will combine the local oscillator
> and the mixer, for example.
Well, in the UK, a 'pentagrid converter' was very uncommon except in
battery sets. Most mains superhets used a triode-hexode frequency changer
- one 'bottle', but separate oscillator (triode) and mixer (hexode)
sections.
> Tim. (shoppa_at_triumf.ca)
--
-tony
ard12_at_eng.cam.ac.uk
The gates in my computer are AND,OR and NOT, not Bill
Received on Sun Jun 22 1997 - 22:21:51 BST