Today I was working on a new-to-me VT240 which hadn't been powered up in
a long time (possibly 10 years). Hooked it up to an old 9" B&W CCTV
monitor and everything was running fine for 20 minutes or so - when
suddenly an astonishing amount of acrid whitish-gray smoke started
pouring from the vents =8^ O
So I yanked the power cord out and took the case off. Sure enough, one
if not both of the 0.1 uF X-caps on the line filter had cracked open and
my nose confirmed that was the source of the stench.
Fortunately there is no damage to the PC board or surrounding components
- even the caps don't look toasted, just split. Good thing I was sitting
right there when they failed and could turn the power off immediately.
I've read here and elsewhere about the spectacular failure modes of
these caps, sometimes flames, but this is the first time I ever
experienced it first hand. Maybe it's time for a look inside my VT220? ;)
-Charles
Hi, I've recently come across a CPU chip marked "AlphaMicro" . It has a
date stamp of 8531 and appears to be of the 386 variety (1 5/8 x 1 5/8). It
doesn't appear to be from Alpha MicroSystems. Anyone know who may be the
maker of this chip? I can send a picture for those who'd like to see what
it looks like.
Hi!
I just wanted to drop an email that there's a MDS 80 on eBay:
https://www.ebay.de/itm/333612000595
(Please note: The seller, Michael, is a friend of mine, and a former
coworker.)
Thanks,
Jan-Benedict
--
Working on restoring this 11/83, I would like to replace the Fujitsu
2284E drive with a slightly larger capacity CDC/Imprimis WREN VI
94246-383 ESDI. I think I have the jumper configurations, however the
problem is the disk does not have a terminator pack.
Does anyone know what kind of resistor pack was used for the CDC drives?
It's probably something very basic and easy to find at Digikey but what?
Thanks!
Chris
(working away here)
Title says all,
Backing up all the programmable parts in the Apollo DN100 and the CPU board
has a few of these ceramic DIPs with the same Apollo P/N labels as the
Am27S29 and similar programmable parts.
Thanks
Classic Computer Fans,
I tried out the CYBIS release:
http://www.Control-Data.info/CybisRelease.html
on the DtCYBER emulator when it first came out. I've since forgotten most
of what I'd learned. Recently I fired CYBIS back up and started relearning.
Does anyone know if any user mailing lists for the DtCYBER emulator and/or
the CYBIS release? At the moment I'm trying to find a Linux friendly
terminal type that works with NOS's FSE.
--
Kevin
http://www.RawFedDogs.nethttp://www.Lassie.xyzhttp://www.WacoAgilityGroup.org
Bruceville, TX
What's the definition of a legacy system? One that works!
Errare humanum est, ignoscere caninum.
On Fri, 22 May 2020, Boris Gimbarzevsky wrote:
> Thanks for posting the timeline of various Basic interpreters. I wasn't
> aware that Gates/Allen also wrote Basic for C64.
Microsoft did a BASIC for the Commodore PET. I wasn't aware that they did
the C64.
> Did download the 8080 Basic source code out of interest, but in early
> 1980's had very little to do with IBM PC.
PC was 8088, NOT 8080.
BUT, an original 8080 source code can be run through some algorithmic
translation to automagically patch it into something that is close enough
to 8088.
All of my knowledge of the following is third hand, and probably mostly
WRONG. If you are lucky, maybe some of the folk here who actually KNOW
this stuff will step in and give the right information.
Sequence is only approximate.
Well, we can start by considering the 4004. 1971. It was not the "FIRST"
microprocessor, although the later chips based on it dominated the market.
4 bit data bus. It was designed to be able to make a whole range of
Busicom calculators that could be essentially the same hardware, and
changing ROM, or moving a jumper from cheapest model to most expensive
model would void the warranty.
Then came the 8008, with EIGHT bit data bus, and 14 bit address bus (16K
of RAM)
Then came the 8080, with 8 bit data bus and 16 bit address bus (64K of
RAM) That brought about a giant surge in hobbyists trying to build
computers, including the MITS Altair, etc.
It is important to note that each Intel chip consisted of "minor"
modifications to the previous one. That made it easier to modify a design
or software from one to the next one. Minor patches tended to be all
that was needed. THAT is important. 'course it means that some aspects
are really weird due to being patched on top of patched, on top of
patched, instead of redesigned.
MEANWHILE, other companies started trying to get into the game.
Motorola came out with the 6800, which was pretty cool.
But, they were taking a long time to get around to the next ones, so a
group of engineers left and started MOS Technology, and came out with the
6500. Motorola's lawyers were not amused. So, the engineers redesigned
an all new, "non-infringing" one called the 6502.
Motorola eventually got around to trying to design "the best 8 bit
microprocessor", and came out with the 6809.
They had designed from scratch, to try to make it the best, so it had so
much different, that previous machines could not be easily modified for
it, and had to be redesigned for it, and software needed to be re-written,
not just patched.
They had difficulty finding any takers, in spite of obvious design
superiority, because most manufaturers were already established with other
chips. BUT, Radio Shack built a machine called "the Radio Shack Color
Computer" around a Motorola application note. Radio shack didn't want it
competing with their other products, and didn't see any reason to include
capabilities, so they had horrible constraints, such as chiclet keyboard,
unexpandable RF video, cartridge slot instead of expansion bus, etc.
A lot of the early machines were intel 8080, which had 8 bit data bus
and 16 bit address bus, which meant maximum of 64K of RAM, although it was
not very hard to cheat for 128K.
Gary Kildall needed an OS for managing his source code on 8 inch disks
that he added to his computer. He wrote "Control Program and Monitor",
which later became "Control Program for Microcomputers" ("CP/M"). He
tried to get Intel to market it, but they didn't think that there would
ever be enough market to sell an operating system for a microcomputer.
So, he started "Intergalactic Digital Research"
Later, when the hobbyists grew up and lost their sense of humor,
"Thinker Toys" became "Morrow designs". (they had been having some
trademark issues)
"Kentucky Fried Computer" became "Northstar" (they had been having some
trademark issues)
and "Intergalactic Digital Research" bcame "Digital Research Incorporated"
Then Zilog came out with the Z80, which had major enhancements.
BUT, code using those enhancements would not run on an 8080, so CP/M
remained 8080, and many/most? programmers stuck with 8080 for marketable
code.
Intel came out with the 8085, which had DIFFERENT [incompatible]
enhancements, so many/most? continued to stick with 8080 code.
I think that the Radio Shack model 100 is 8085.
A hobbyist named Steve Wozniak wanted to build a Z80 computer. But it was
going to cost too much. At Wescon (trade show), he got a fantastic deal
on some 6502 chips. Not what he had been wanting, but he could make it
work, and he could afford them!
He hooked up with Steve Jobs, who had some marketing ideas. They sold a
bunch of "blue boxes", kited some checks, sold Jobs' VW bus and Woz's
calculator, and put together a batch of kits. ($666.66; they later said
that they had not realized the theological implications of the price)
And, hence, we got "Apple Computer". Later, Apple Music (Beatles) talked
to them about the name. Apple Music agreed to not get into computers, and
Apple Computers agreed to not get into music. Hmmm.
Atari and Commodore both ended up also using the 6502.
Motorola
Then Intel decided to build a "16 bit processor". The 8086 has a 16 bit
data bus and a 20 bit address bus, for a maximum of 1M or RAM
When the IBM PC wasbeing planned, there was a lot of difference in cost
between 8 bit and 16 bit support chips.
The 8088 was ALMOST the same as an 8086, but with an 8 bit data bus, which
significantly reduced costs! From an engineering perspective, the 8088 is
an 8 bit version of the 16 bit 8086.
>From a MARKETING perspective, it's 16 bit, or maybe 32 bit, or maybe 64
bit, etc. If a 4 bit machine has a 128 bit Smell-o-vision port,
marketing will call the machine "128 bit"
The IBM PC was an 8088.
IBM went to Microsoft to get BASIC for it. Bill gates put on a suit and
met with them.
The "Pirates Of The Valley" story of Microsoft cold-calling IBM to sell an
operating system PINS THE NEEDLE ON THE BOGUSIMETER. The author of that
fiction needs a hot soldering iron shoved 8 inches up his nose.
Microsoft was happy to oblige on BASIC.
One of the IBM engineers had an Apple2 with a Microsoft "Softcard" (Z80)
to run CP/M. So, IBM asked Microsoft to also supply "the CP/M".
Bill Gates explained that that was Digital Research.
So, IBM went to Digital Research in Pacific grove to get "the CP/M".
There was some "culture clash". IBM showed up in blue suits. There is an
unconfirmed report that somebody at DR thought that it was a drug raid. I
have looked out that upstairs window, and can imagine it.
The IBM suits encountered barefoot workers in shorts and not all wearing
shirts (both sexes?) female workers without bras. cats and a dog. plants.
Surfboards and bicycles in every room.
Gary Kildall wasn't even THERE! He had gone to fly his plane up to
Oakland to visit Bill Godbout. Official story is that that was an
essential errand to deliver some documentation (and no lower employee
could have put some shoes on and driven up?). His wife was there, and he
had told her, "They're just coming to sign a license agreement. Let them
wait in the living room with the rest of the customers."
IBM was not amused.
IBM went back to Microsoft. I heard that Bill Gates told his people that
anybody without a suit should stay home for the day.
IBM said that they wante Microsoft to provide the OS. Bill Gates said,
"we do BASIC. We don't do operating systems." IBM said that they
intended to get the BASIC and the OS from ONE source. Bill Gates said,
"Let me tell you about our new OS department!"
Then Bill Gates went down the street to Seattle Computer Products and
bought 86-DOS/QDOS ("Quick and Dirty OS"), including hardware to run it
on, and the contract of Tim Paterson who wrote it.
Microsoft had a new OS department.
Motorola STARTED work on "The best 16 bit processor". Rather than
patching something earlier, and being stuck with legacy oddities, they
designed from scratch. So, it took longer.
Motorola eventually came out with the 68000, which was the best 16 bit
processor. (or 32 bit or 64 bit if you are in marketing)
The Apple3 was a major financial setback. Much more money, for very
little more.
Apple started on a total redesign. It is rumored that for the Lisa, they
explicitly avoided anybody with prior experience to avoid repeating
previous bad ideas. 'course hiring brilliant folk straight out of college
meant that nobody had the prior experience to know the consequences of
building a machine for which software could NOT just be patched from
previous versions. The Lisa was magnificant! and in a price range
(>$20K?) where sales were to overpaid exectuvies wanting to impress other
overpaid executives. It actually came close to putting Apple on the rocks.
And, it was an ALL-NEW (and improved) machine. Old software couldn't just
be patched, it had to be re-written.
The brilliant recovery plan was to take the Lisa design and cut every
corner that could be cut, to make a machine that could be sold for $500.
Once they did, they found that they could still get away with selling it
for $2K. it was mandated that the resulting machine would come with four
significant pieces of software. By the time it was ready, those had
become Mac-Write, Mac-Paint, Mac-Write, and Mac-Paint. But that was
enough. The marketing people were smart enough to change the grumbling
about building a computer for ignorant masses into "a computer for the
rest of US"
Later, Commodore (Amiga) and Atari (ST) used the 68000. There are some
amazing stories (that i don't know) about that "technology swap"
Intel came out with the 80286, 16 bit data bus with 24 bit address
bus. with fewer limitations. But still a few
significant ones, such as how to switch in and out of "protected mode".
"It's like having to turn your engine off to switch gears on the freeway".
Bill Gates called the 80286, "Brain dead."
In "real mode", which would be limited to 20 bits of address, it is easy
to cheat and enable A20, which permits 64K past the 1M boundary. THAT is
required for Windoze 3.10
Then came the 80386, which could sorta be called a 32 bit processor. And
the 80386-SX, which analogous to the 8088, was a 16 bit version of the 32
bit 30386, permitting building a software compatible machine using cheap
80286 support chips.
80486, which is kinda like a 80386 plus 80387 math chip, and the 80486SX,
with is 80486 without the math processor.
and Pentium. Intel had been finding out the hard way that it was
difficult to maintain trademark of a number (Oldsmobile "442"
notwithstanding) Other manufacturers would make a 80386 like chip and
call it a 486, or an 80486 like chip and call it a 586, etc. So, they had
a naming session. And the other entries were even worse than "Pentium".
I'm surprised that that didn't backfire horribly! Consider: In about
1965, Honeywell bought Pentax from Asahi. Honeywell could totally
legitimately have come out with a processor (joint venture with
AMD/Cyrix/etc.?) and called it the "Pentaxium". Intel wouldn't even be
able to object.
Yeah, there have been more since then, but new stuff isn't interesting for
another ten or twenty years. OR MORE for some of the boring current
stuff.
--
Grumpy Ol' Fred cisin at xenosoft.com
> As was working with PDP-11's at that time, really disliked 8080 instruction
> set and got a C64 instead which was considerably cheaper than IBM PC and much
> easier to write assembly code for. C64 basic is fairly ugly but bought a
> 6502 assembler and just used Basic to display stuff on screen and call my
> work was done in assembly language code. Had no trouble sampling switch data
> at 1 KHz using my "toy" computer. A couple of guys from UBC Physiology
> decided to build a programmable stimulator based on C64 which they were
> trying to sell for $2K, considerably less than the ~$10 K that the dedicated
> device that was commonly used then. Even though their timing specifications
> matched the expensive device, a lot of researchers back then didn't want a
> "toy" to be part of their lab setup so sales were few.
>
> Recently found a movie Pirates of Silicon Valley which had some of early
> Microsoft history and, if depictions of individuals are true to reality,
> explains why I far preferred Mac in comparison to ugly early windows. It
> also helped that 68000 was a very easy processor to migrate to after 8 years
> doing assembler/FORTRAN programming on a PDP-11. Couldn't believe it when I
> had a full 512 Kb of RAM to play in.
> From: Jon Elson
> As far as I know, there was no VM/360. There WAS VM/370, which was out
> in the early 1970's
CP/67, which was a semi-product, and ran only on 360/67's, was basically the
same functionality as VM/370. (I get the impression that the code was
descended from CP/67, but I can't absolutely confirm that - although see
Varian, below.) It was used by many customers who had purchased 360/67's.
The 370/67's instruction set didn't need to be tweaked at all to run a
virtualization (although it had added hardware to do virtual memory, which
CP/67 needed); the '360 Principles of Operation' was defined in such a way
that it could be virtualized. (Unlike, say, the PDP-11, where a RESET
instruction in User mode is a NOP, and does not trap). All that's needed is
the virtual memory hardware, because otherwise the real addresses of the
underlying machine have to be exposed to the virtual machines.
CP/67 was preceded by two earlier iterations: CP/40, which ran on a special
360/40 which has been hacked to have paging hardware added; it was likewise
almost identical to CP/67 (a hacked version of CP/40, with the memory
management of the 370/67 substituted for the special 360/40's, was booted on a
360/67). An older system, M44, which was similar in functionality (although
not a perfect virtualization of the underlying machine), it ran on a modified
7044.
One version of CP/67 provided a /370 virtual machine; it was used
extensively by the MVS development team. CP/67 was also brought up on
/370 hardware.
Full details in "VM and the VM Community: Past, Present and Future",
by Melinda Varian.
Noel
Still looking for the matching? paper tape reader and punch.? For one of these...Ed#
On Sunday, May 31, 2020 Jan-Benedict Glaw via cctech <jbglaw at lug-owl.de; cctech at classiccmp.org> wrote:
Hi!
I just wanted to drop an email that there's a MDS 80 on eBay:
??? https://www.ebay.de/itm/333612000595
(Please note: The seller, Michael, is a friend of mine, and a former
coworker.)
Thanks,
? Jan-Benedict
--
