6809 (was: Anybody ever use Aztec C for APPLEII?)

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Apr 28 17:53:28 2004

> So? Most (all?) 8-bit CPUs have that "limitation" -> which can be easily
> overcome with bankswitching and other techniques...

Motorola actually sold an MMU chip for the 6809 at one point (I have the
data sheets, but have never seen the chip). It was something of a kludge
-- you could load the new page number and a number-of-cycles into the
chip. After than number of clock cycles, the page changed. That let you
do a jump instruction on the 6809 at the same time, so you ended up
directly at the right address in the new page.

> 2) Show me a "reasonable OS" for anything Intel based. Then show me the
> ones that existed back in '86 or before. Then show me the ones that will

Dynix on a Sequnet Symmetry?

> run on anything <'386. Then see if any are left that cost <$150. The list
> gets *real* small, *real* quick. OS-9 is a reasonable OS, was first written

OK, you win. FWIW, OS-9 was my first 'real OS', and I loved it. I still
think some features, particularly the I/O system, are really well designed.

> Heck, the CoCo tape unit is almost as fast as the Commie disk drive, and
> could be tweaked to go faster! Also, Later CoCo2s & all CoCo3s had

What 'later CoCo2s'? That sounds like the 'Deluxe Colour Computer', and
AFAIK that was never officially sold (there are rumoured to be a couple
out there).

> lowercase builtin... and RS had a cartridge that would give you a full
> 80x25 mono screen w/lower case (and full decenders, too!) if you needed to

I rmember such cartridges being sold in 'The Rainbow' magazine, but I
wasn't aware Radio Shack ever sold them.

> How does [[ Crappy graphics, crappy sound, great I/O speeds & Unix-class
> multitasking OSs ]] == "Game Machine"???

'Crappy Sound'? Not if you added the Speech/Sound cartridge. That
contained a microcontoller, AY-3-891x sound chip and SPO256 speech
synthesiser. It was as good as the sound on other machines of the time.

I guess what I disliked most about the CoCo was the physical design. You
rpetty much had to have the Multi-pack if you were doing anything serious
with ti, then you had the disk cotnroller, serial port cartridge, a
couple of homebrew things (look, this is _my_ machine :-)) plugged into
that, etc. Not a very convenient layout. I would hae prefered a PC-style
case (Yes, I know people repackaged their CoCos, but...).

-tony
Received on Wed Apr 28 2004 - 17:53:28 BST