TRS-80 Model I

Liam Busey buseyl at yahoo.com
Sun Feb 4 13:39:35 CST 2007


--- Chuck Guzis  wrote:

> On 4 Feb 2007 at 0:56, Tony Duell wrote:
> 
> > And another oddiity. The whole design of the Apple
> ][ seems to have been 
> > to save a chip if at all possible (provided the
> machine still works -- 
> > just). And yet the kayboard was encoded in
> hardware.
> Why? It meant you 
> > couldn't implelement a lower case keyboard in
> software (there are the 
> > well-known shift key mods where you run a wire
> from
> the shift keyswitch 
> > to one of the single-bit inputs on the games
> connector, which shouldn't 
> > have been necessary).
> 
> Thank you for absolving me of being the first to use
> the term 
> "gutless wonder".  :)

LOL. That has a certain ring to it. 

It gives character. :)
 
> In a way, I suppose the disk controller was a clever
> design.  But it 
> locked the CPU into 2MHz operation.  The use of a
> simple arithmetic 
> checksum for each sector was not perhaps the most
> reliable solution 
> either.  But the biggest problem is that disk
> reading
> and writing 
> required 100% attention from the CPU.  On most other
> computers that 
> used dedicated LSI controllers, the possibility
> existed for 
> overlapped computation/disk access.

Oh yes, that's a huge gotcha with the disk II. It
could make communications software or data logging
interesting.

There were other disk systems for the Apple though
none as ubiquitous.

I like the Disk II. I don't think it was the ultimate
disk system, just a clever/ cheap one (for Apple at
least).


Liam Busey


 
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