Hi
I am being offered this computer.
I think it's 3 large modules.
I have large collection of micros from the 197x-198x but, I know almost
nothing about vax'es...
I would we prepared not to keep it or donate/trade parts or whole...I
have no real space to keep this for a long time...
It would be in Montreal, Canada.
Is it worth the hassle of picking it up? What should I check for?
My wish list : TRS80 III (I and IV too), NExT, older CP/M systems...
Thanks
Claude
From: Eric Smith <eric(a)brouhaha.com>
>> Hint the KA650 was not a upgrade only cpu, it happens that it's Qbus
>> and fits in any BAxx3 box.
>
>And those don't say "MicroVAX III" on them anywhere, now do they?
None did. From MVII on the term became just Microvax despite going
>from MVIII, Nvax, NVAX-5 and other varients of the VAX on a chip.
if You wanted a MicrovaxIII cpu in a new box you bought a Microvax3x00
(3200, 3400).
Allison
>At 08:28 AM 11/4/00 +0000, Eric Smith wrote:
>>Although it appears that DEC did not sell a MicroVAX III as a new
>>product, they offered a MicroVAX II to MicroVAX III upgrade that
included
>>the KA650, MS650, and a new nameplate.
Yes and the 3200, 3400 and 3600 seris VAXes had what cpus?
Hint the KA650 was not a upgrade only cpu, it happens that it's Qbus
and fits in any BAxx3 box.
Allison
>I'm not including internal temporaries that are not
>exposed in any way either. But depending on how your
>hardware is wired, the NMI edge detect flop can have
>substantial influence on how you write your interrupt
>handler. Thus it is in fact programmer visible, though
>not as much as e.g. the Z-80's R register.
It is a feature as they say. I like to use it for a RTC
heartbeat as you bang it with and edge. Hard to use
for CP/M as it hits the default FDB.
Z80 is as feature rich a cpu one could ask for at that time
or since. Z180 and all added some nice touches.
I happen to like the 8085 for mid sized tasks that are too
big for 8048/9 but Z80 may not fit as well. SIN/SOUT and
the four RST{5.5, 6.5, 7.5,TRAP) lines are handy for
some things. THose interrupts and IO lines offere more
than most minimal z80 systems without Zilog peripherals.
The 8085 is often forgotten despite being a decent chip.
Allison
>I'm not including internal temporaries that are not
>exposed in any way either. But depending on how your
>hardware is wired, the NMI edge detect flop can have
>substantial influence on how you write your interrupt
>handler. Thus it is in fact programmer visible, though
>not as much as e.g. the Z-80's R register.
It is a feature as they say. I like to use it for a RTC
heartbeat as you bang it with and edge. Hard to use
for CP/M as it hits the default FDB.
Allison
From: Eric Smith <eric(a)brouhaha.com>
>Allison wrote:
>> To be exact the z80 has
>[list of registers deleted]
>
>You forgot IFF2. :-)
I know that but consider who most of this is aimed at.
No question the z80 has many more bits than 6502,
8080, 8085, 9900, and a pot load more. Only the 1802
has more stoarge (though simpler elsewhere).
>And both the Z-80 and 6502 have at least one more
>bit that's "sort of" programmer visible, the NMI
>edge-detect flop.
I tried to limit it to the programmer accessable. If
we add temp registers and whole knows what in the
state or microcode portion of the machine it surely
would grow more.
The 6502 distinguished itself in the same fashon as PDP-8.
That is it was simple, cheap to manufacture and had an
adaquate instruction set to do a lot of tasks. it's cheapness
was due to the ease of implementation in silicon.
>
>> 6502
>> SP 9BIT (HIGH BIT =1)
>
>It's either 8 bits, or 16 bits with the high 8 being stuck at
"00000001".
>There's no meaningful reason to consider it a 9-bit register. I
personally
>only find it sensible to count the bits that change, so I call it 8.
Agreed. The 9bit comes from the Osborne view of microprocessors.
>
>> STATUS 8BIT
>
>7 bits, or 8 with one bit stuck high..
same deal. We can consider the unused bit as "reserved".
Allison
If the connections are only to the video board, then the "magic switch" is
simply a way of adjusting the "height" of the display. In one position, the
video is full height, with the standard Lisa rectangular pixels. In the other
position, the video is vertically squashed to produce square pixels. Its
pretty low-tech. The device probably has adjustable resistors somewhere on a
small circuit board in order to tweak the display for each position of the
switch. If you pull it all off, you have just the standard Lisa (full height)
display.
I think that it would be pretty straight forward to homebrew one of them.
The real Apple-supplied modification was more involved and produced a full
height, square pixel display. It included a transformer which modified the
screen height, a new video rom (which controlled generation of video sync
signals and the Lisa serial #), and new boot roms.
John
jlewczyk(a)his.com
-----Original Message-----
From: owner-classiccmp(a)classiccmp.org
[mailto:owner-classiccmp@classiccmp.org]On Behalf Of Marion Bates
Sent: Saturday, November 04, 2000 2:52 PM
To: classiccmp(a)classiccmp.org
Subject: Lisa WEIRD!
Okay, so after my post I went and fiddled some more and lo and behold, after a
few more power cycles it booted perfectly from the hard disk. It's running
MacWorks Plus some version or other with Mac System 6.0.3. The hard disk sounds
like it's full of sand (yikes) but otherwise it seems to be fine. :)
This is where it gets bizarre. I took the top lid off to get at the video
adjustment pots and managed to eliminate the vertical jumping etc. so the
screen is pretty much back to normal operation. But inside, on that same board
just below those adjustments, I saw two or three sets of jumper wires, the kind
with the little spring-loaded L-clip at the end. One end of one of them is
clipped to R1 right near the top of the board, and I can't see where the other
end is without really gutting the machine, which I'm not ready to do just yet.
Another jumper has one end connected to a leg of R21 and then it disappears
inside. It also looks like there's a small alligator clip connected to a heat
sink and leading off somewhere else.
So it looks like someone went in there and jumped some connections, then closed
it all back up and left it that way. I'm afraid to touch them. Maybe this is
related to the mystery switch (see my earlier post). Strange... ? Somebody
hotwired this Lisa?
-- MB
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