11 Feb
2006
11 Feb
'06
8:13 p.m.
I want one anyway. I WANT IT I WANT IT! Another
minimum mode 8088 I seem to perceive. Used to think
that amounted to an 8085, but its not limited to 64k.
Chuckie also chose a non-conformist Hitachi crt
controller. I ran across something else that used it
the other day, but I forget what it was.
--- cctech-bounces at classiccmp.org
<ard at p850ug1.demon.co.uk> wrote:
Chuck Peddle influence,
>
> what you get someone whos got everything else. Or
at
> least every other IBM incompatible on the planet
(ok
Im not quite
there). Also a must for the truly
masochistic (gcr floppies). What every guru/sicko
The hardware is a bit odd... It clearly shows the it's full of 6522s (3 on the mainboard, 3 on the
disk controller), and
the disk read/write circuit is very similar to that
in a Commodore PET
drive...
A couple of odd things. Firstly, the Centronics port
is driven by GPIB
buffers (75160 and I think 75162). A 'little
matter
of programming' and
the right cable would get you a GPIB port there,
Then there's the user port. A 50 pin header on the
mainboard. It's almost
a complete 6522 (I think one of the port lines is
used to clock the sound
circuitry), along with a light pen input and power
lines. Odd....
And the sound iput. THe encoding half of the codec
is wired to the
receive side of the 6852. The input to that codec
comes from a pin on
header on the mainbosrd (along with power lines,
ground, etc). It would
not be hard to feed an audio signal in there, the
hard part would be to
write/find the necessary software....
-tony
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13 Feb
13 Feb
7:18 a.m.
I want one anyway. I WANT IT I WANT IT! Another
minimum mode 8088 I seem to perceive. Used to think
I think so, but I would have to find the schematic to be sure.
that amounted to an 8085, but its not limited to 64k.
Chuckie also chose a non-conformist Hitachi crt
I thought it was just amother 6845-a-like. But it addresses 2K*16 bits of
SRAM, some of the outputs of which are used as part of an address to the
main system DRAM which cotnains the character bitmaps (!). Not
suprisingly, the Apricot does the same thing.
There are enough outputs taken from the SRAM to form that address that
each character cell on the screen can have a different bitmap assigned to
it, thus allowing a rather eccentric bitmapped graphics mode.
Oh yess, the brightness and contrast of the monitor are controlled by 2
3-bit ressitor ladder DACs driven by yet another 6522...
-tony
5:10 p.m.
--- Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Pretty sure it was a Hitachi something or other. At
least according to the BYTE review *not in front of
me*. Whether or not that amounted to a 6845
clone...dunno.
The TI PC used a 6545. I think there may even have
been a discussion about it recently. Is that
essentially a 6845 clone? I think I even have the app
note for it somewhere...
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Chuckie also
chose a non-conformist Hitachi crt
I thought it was just amother 6845-a-like.
15 Feb
15 Feb
4:21 p.m.
Pretty sure it was a Hitachi something or other. At
least according to the BYTE review *not in front of
me*. Whether or not that amounted to a 6845
clone...dunno.
The TI PC used a 6545. I think there may even have
been a discussion about it recently. Is that
essentially a 6845 clone? I think I even have the app
I think so (and I think the Hitachi one was as well). There may be minor
differences, IIRC one manufacture let you read back any of the internal
registers, on the original Motorola part they were write-only (the only
thigh you could read were the light-pen latches).
-tony
6884
days inactive
6888
days old
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