TRS-80 Model I
ard at p850ug1.demon.co.uk
Sun Feb 4 16:03:41 CST 2007
> I see nothing wrong with that. The Tandy machines
> seemed like decent computers for the money. I wouldn't
> mind picking up a TRS-80 someday.
If you don't want 'the first', try to get a Model 4, original
(non-gate-array) CPU board versions. It's got a couple of features not
found on the earlier machines, including an 80*24 text mode display and
selectable memory mapping allowing RAM at location 0 so you can run
normal CP/M as well as TRS-DOS, LDOS, etc. And the origianl CPU board is
all standard chips with some PALs dotted about,
> Strange, I haven't noticed any stability problems with
> my ][ and ][+ under similar loads. Still, an unstable
> machine is unlikely to impress.
i must admit my comments are based on one machine, and are hardly
scientific. Perhaps my machine had chips that drew more current than
average, or someting (still, a good design would haev taken the
> Would you recoil in horror if I told you that some
> companies made single sided 40 track 3" (Amdisk) and
> double sided 80 track 5.25" (Rana Elite 3) drives for
> use with the original Disk II controller? ;)
Yes, I remember seeing those advertised in Byte. Still, they came out a
good few years after the Apple drive, and even then the choice of drives
as limited compared to, say, the TRS-80.
> > The first seiral port for the Apple ][ was a
> > bit-banger. It was the only
> > one I had for some time, and it was almost unusable.
> > The TRS-80 used a
> > real UART, and worked. Yes, there were better serial
> > ports avaiable for
> > the Apple later.
> Was this an early serial board or were you using the
No, this wa a plug-in card which went into one of the normal Apple slots.
It contained a couple of firmware ROMs, a few TTL parts, an opto-isolator
and some discretes.
All it implelented was TxD and RxD (no handshaking at all). It did have
both current loop and RS232 I/O. The lack of handahake inputs was a big
problem. Ordiarily you'd have used software flow control (XON/XOFF, for
example0, but the darn thing was a bit-banger (and Apple didn't believe
in interrupts) so you couldn't reliably receive the handshake characters.
It was a genuine Apple product, I still have it somwhere along with the
> game port? I've always enjoyed the luxury of a 6551
> equiped board (Super Serial Card II).
I've also seen 6850-based serial cards for the Apple, but I don't think
they were Apple products (CCS or somebody).
> I think Woz was allergic to peripheral chips in the
> beginning. :)
Unlike Chuck Peddle who had a love of 6522s (the Sirius/Victor 9000 has 6
of thtm in it...)
> The colors are NTSC artifacts! :) I thought that was a
> neat hack. How did they deal with that in PAL land?
Well, there was the ;'Eurapple mod' which was a couple of cnt/blob
changes to the main PCB and a different master clock crystal. That got
you Europane video timing, albeit without PAL colour (most, if not all
Apples ][ machines sold over here came with that mod done). There was a
board you put in Slot 7 (which had soem extra timing signals brought out)
which did the appropriate phase-shifts to get PAL video. Or there were
3rd party board to give RGB video.
> Bingo! Legend has it that Woz's aesthetic ideal was to
> bum a design down to as few chips as possible. Almost
> a Madman Muntz I suppose.
> Methinks you're not a fan of Clive Sinclair either? :)
How ever did you guess :-). No I don't much care for his kludges. Suffice
it to say that I once did battle with a QL (which at the time sold for
\pounds 400). My comments were that had it sold for \pounds 600 but had
working serial ports, a real keyboard, and a disk drive, then I might
have actually bought one.
> understand where you're coming from. I like the Apple
> because I feel it's a machine with interesting
> capabilities yet made from a small amount of simple
> parts. It's a machine I can both grasp and enjoy.
I am suprised by that last comment. Actually some parts of the Apple
hardware are quite difficult to understnad properly becuase they do use
unobvious tricks to save components. It reminds me of some of the
circuits you find in those Radio Shack '300 in 1' kits. Some of those are
not easy to follow IMHO.
In may ways a somewhat more complicated computer can be easier to
understand because everything is done in the obvious way without trying
to save every last gate.
> What's your opinion of the BBC Micro? I've never had
> the pleasure of using one, but on paper it sounds a
> lot like a fast Apple II with a pair of 6522, 6845,
> hardware ACIA, 1770 FDC, and enhanced basic.
I'd rather have an ACW :-) (This is a joke which I'll explain in a moment)
The BBC micro is IMHO,. the best 6502-based home computer ever, it's one
of the best of the 8-bitters (no matter what processor). The only thing
the Apple has that the Beeb doesn't are the expansion slots. But a Beeb
has a printer port, disk controller (8271 on early machines, 1770 on
later models),serial port (The ACIA is also used for the cassette
interface, BTW), ADC, user port, expansion bus, etc. And the BASIC is
excellent. Named procedures with formal parammeters and local variables,
multi-line functions, built-in assembler, etc, etc, etc. And there are
bank-switched ROM sockets where you can put other language ROMs (or
Now for the omment on the ACW. An ACW is an Acron Cambridge Workstation.
Take a BBC B+ (64KL RAM) board. Put it in a case with a colour monitor,
floppy drive and hard drive. Now add a coprocessor board containing a
32016 and 4M RAM (!). As a workstation it's let down by the BBC's
graphics (excellent for a home computer, but not up to workstation
standards). But as a 'home micro' it does everything the Beeb does and a
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