[Discuss] Old computers Re: (OT) Steve Jobs 1955-2011
Rich Braun
> My first home computer was an Apple II (1978). What Jobs saw back
> then was that a desktop computer could be useful to real people.
> At the time, there were a few hobby computers. I almost bought a
> MITS Altair
The first desktop I ever ran across was in my math teacher's class in
Arlington, VA in 1977: an HP 9830A (you can find pics of it via Google).
Anyone else remember those? It had 4K of RAM, kept your programs on a
cassette tape, printed out (quickly) on an 80-column wide thermal printer.
You programmed it in BASIC; I remember writing a banner printing program and a
biorhythm chart generator.
Being exposed to bigger mainframe computers starting around '72, I never
thought of these micro things as anything other than toys. So when the TRS-80
and Apple ][ came out, they held little interest for me--my first
factory-built (i.e. not cobbled-together) home computer was a 1982 DEC surplus
PDT-11/150; it ran RT-11. The first "real" home computer, that rivaled
mainframe performance, came along about 10 years later: the Intel 486.
That's when speed-of-light constraints came to favor microchips over the
"frames" containing CPUs in multiple circuit boards spread across a backplane,
and transistor density has accelerated ever since.
By the time of the 486, Linux was available: today's supercomputing clusters
usually run Linux.
-rich
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Shirley Márquez Dúlcey
The first computer I had any personal experience with was an IBM 1620.
20K of BCD digits, and the peak instruction rate was about 6,000 per
second. (The memory cycle was 20 microseconds and the shortest
instructions took eight cycles.) Oh, and a hard disk that stored 2M of
BCD digits.
After a year my school replaced it with an IBM 1130, which was hardly a
powerhouse either: 8K bytes of RAM and a peak execution rate of perhaps
80,000 instructions/second (5.85 microsecond cycle time and most
instructions took multiple cycles). Oh yes, another hard disk; this one
stored one megabyte and used stepper motors that made a loud saw-like
noise during seeks. Although it was a hard disk it was no faster than a
floppy drive.
I did have some exposure to more powerful systems at the nearby state
university. They had a midrange 370 system (370/155 if memory serves)
that was used in batch mode (submit deck of cards, come back later for
printouts) and a PDP-10 timesharing system with ASR-35 terminals.
Once home computers had floppy drives they were already exceeding the
performance of the 1620 and 1130 (though the early floppies didn't have
as much capacity as the hard disks did) so they were never toys to me.
It was a while before I could scrape up the cash to buy one of my own (I
had an SWTPC 6800 kit that I never quite got to work properly, and later
an Atari 800XL) but I certainly wanted a home computer right away!
Matt Shields
Mine was a Commodore Pet. Dad bought one for his business and one for home.
Matthew Shields
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Jerry Feldman
>
>
card input in 1965. I learned FORTRAN 2, and subsequently BASIC for a
feed into GE Time Sharing as an undergraduate. In graduate school we had
a DEC PDP-8 with a hard drive. I recall a DEC service guy coming in to
clean the drive. We did not have mag tape, so input was from PPT, TTY,
or punched cards. One project I did was to replace the printer driver
for the Potter Printer. I would spend hours in the lab.
--
Jerry Feldman <g...@blu.org>
Boston Linux and Unix
PGP key id:3BC1EB90
PGP Key fingerprint: 49E2 C52A FC5A A31F 8D66 C0AF 7CEA 30FC 3BC1 EB90
edw...@linuxmail.org
1980). Programs loaded in via cassette tape.
Computers have indeed come a LONG way since then.
MBR
Group at DEC from 1972 to 1977. RT-11 was developed as a successor to
OS-8. The PDP-8 (12-bit word, 3-bit opcode, maximum memory
32K-12-bit-words) was to the world of computers in the early 1970s what
the Model T had been to the world of automobiles in the 1910s. While it
was severely limited compared to mainframes of the day, the PDP-8
brought the price down to the $10,000 to $20,000 range, a price where
every college psych lab could afford their own computer to monitor
experiments and process data.
DEC's mainframe at the time was the PDP-10 (36-bit word, 9-bit opcode,
maximum memory 4M-36-bit-words), which typically cost many hundreds of
thousands of dollars. TOPS-10, the PDP-10 operating system, time-shared
among lots of terminals. I don't remember what its limit was, but I
think 50 users at a time was not unusual.
When I joined DEC's Small Systems Group, one member of the group was
legendary -- Ritchie Lary. PDP-8 development had to be done with a
cross-assembler running on the PDP-10. But the Small Systems Group
didn't have enough PDP-8's for everyone to have one, so we each got a
few hours a day on the real PDP-8 hardware. It was extremely cumbersome
to have to assemble your source code on the PDP-10, punch a paper tape
of the binary, wait for your 2-4 hour time slot on the PDP-8 hardware,
load the binary from paper tape, debug your code, and then have to go
back to the PDP-10 and repeat the process if you needed to change
anything in your code. The story was that a year or two before I
joined, Ritchie Lary realized that to do a standard edit, compile, and
debug cycle all on the same machine, he'd need a single-user version of
TOPS-10 running on the PDP-8. So he went off and wrote it! Other
members of the group wrote the necessary utilities. The editor (TECO)
was translated, instruction-for-instruction, to the 8 instuction set.
Someone wrote a native PDP-8 assembler. And thus was OS-8 born! Lary's
original name for it was the _*F*_ully _*U*_pward _*C*_ompatible
_*KE*_yboard _*M*_onitor. Of course, marketing couldn't call it FUCKEM,
so they gave it a more respectable name.
I know that if someone had suggested to me at that time that an OS that
ran in Mega-words of 36-bit word memory could be implemented as a
single-user verison in 8 Kilo-words of 12-bit word memory, with only 256
words resident, I'd have thought the idea was insane! I've always felt
that Lary's ability to see that such a thing could be done and go do it
was true genius.
Around 1973 or 1974, DEC's hardware engineers gave us a brand new, and
quite innovative architecture, the PDP-11. Its instruction set was
nicely orthogonal so it was easy to learn, but was also quite powerful.
Its native post-increment and pre-decrement addressing modes inspired
C's ++ and --.
Our managers came to us and said that because OS-8 was doing so well,
they need OS-8 reimplemented to run on the new PDP-11. That's how RT-11
came into existence.
Gary Kildall's CP/M started out as his own reimplementation of RT-11 for
the Intel 8080. A few years later, Tim Paterson of Seattle Computer
Products (SCP) wrote his own implementation of CP/M called QDOS (Quick
and Dirty OS). Bill Gates didn't write MS-DOS. He simply bought rights
to QDOS from SCP for $50,000 while keeping secret from SCP the fact that
Microsoft's customer was IBM! And that's how the whole chain of cloning
and incremental improvement came to make a fortune for Gates under the
name MS-DOS.
For me, the lessons of this history are:
*
Good software usually involves someone with a brilliant insight
followed by a series of incremental improvements done by
individuals, either collaborating with one another or
unintentionally collaborating by copying and improving each
other's work.
*
Those who reap the rewards seldom have a significant hand in the
creation. Instead they tend to be skilled publicists who make
dubious deals with naive programmers.
I think some, but not all of this, applies to Steve Jobs too. He was
definitely quite skillful at promoting his company, their products, and
himself. He didn't invent the modern bitmapped graphics computer. That
work was done by people like Charles Thacker, Alan Kay, Douglas
Engelbart, Robert Metcalfe, and others that most people have never heard
of. But I think Jobs had vision that allowed him to improve on their
ideas while copying what they'd done, just as Kildall improved on what
we'd done at DEC, and Paterson improved on what Kildall did. In that
regard, whatever other objections I may have had to how Jobs ran things,
I have far more respect for him than for Gates.
Mark Rosenthal
m...@arlsoft.com <mailto:m...@arlsoft.com>
Jerry Feldman
that time, BK's point of sale systems were 8K DEC PDP-8Ms (with no
control panel). The cash register had nixie tubes and a keyboard you
read by reading the row, then column (eg not ASCII). The modem only had
a ring interrupt. To send data, you rotated the accumulator into the
link to send a bit, or from the link to read a bit. The 1200bps was done
in timing loops. The PDP 8 processor speeds were predictable. Since it
had core memory, if there was a power fail, all we had to do was to save
the PC, accumulator and link. The PDP-8 only had those registers plus a
multiplier quotient we did not use, and a 3 bit bank register we did not
use in the 4K versions. Only Connecticut had 8K. At the time, a 4K
memory board cost about $5,000. Each PDP 8 could support a maximum of 4
registers and 8 clerks. (2 clerks could share 1 register). In 4K we
could do inventory, cash reconciliation, hourly sales, and a couple of
other things. We could only store 1 day's worth of data. If the store
failed to send it's data, in the morning the manager had to call Miami.
The printer was a drum printer with only 10 characters. The right side
of the printer was numeric, so we could print 0-9 or a space, and the
left side had Alpha characters, but only 10 letters, so some of the
abbreviations were interesting. We had to write the code to strike the
hammers on the drum. We had a home-grown comms protocol partially
because of the 12 bit data. The Miami host was a Burroughts medium
systems EBCDIC mainframe. Our modem program there was written in COBOL
with integrated assembler. Burroughs medium systems did not have a
linkage editor so your programs were monolithic. So, one of the things
it had to do was to read the 8-bit data convert it back to 12-bit binary
words, then into COBOL integers. The PDP-8 would send 2 words in 3
octets. I was hired as a PDP-8 assembler programmer since I had training
in graduate school. Later on, BK converted to a microprocessor based
system.
--
Jerry Feldman<g...@blu.org>
Boston Linux and Unix
PGP key id:3BC1EB90
PGP Key fingerprint: 49E2 C52A FC5A A31F 8D66 C0AF 7CEA 30FC 3BC1 EB90
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