Do you use any computer based tool for doing project layout?

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And they built computers that couldn't add!
They faked addition by 'complement and subtract'. (true!!)
That said, they were some of my favorite hardware to work on.
The high-level architecture was positively elegant in it's simplicity and regularity.
the closer to the hardware they got, the *stranger* things got.
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On 4/12/2010 8:07 PM, Robert Bonomi wrote:

Was it the IBM-650 that was nicknamed the "CADET" for Can't Add, Doesn't Even Try?
The only CDC machine I ever used was the 6500 at Purdue and it seemed to do crank right along fair reliably.

Speaking of Burroughs... :o)
--
Morris Dovey
DeSoto Solar
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Yuppers. It simulated addition via table-look-up. I never programmed on one of those.

The 6000 series were nice machines, but they did have their quirks.
I, *unintentionally*, was responsible for one University machine crashing nearly _two_dozen_ times in approximately a 1-week period. This accounted for over 90% of all the crashes the machine experienced in two years. <WRY GRIN>
It took a while to establish cause-and-effect, because *nobody* was willing to believe that that 'innocent little job" -- nothing more than 4 standard statements in the system control language -- could _possibly_ be the culprit. Until they ran it as the _only_ job in the system, and watched the machine crash.
The entire job consisted of: 1) request a tape mount 2) copy a file from disk to the tape 3) rewind the tape 4) copy from the tape back to a new file.
{_first_ time using a mag tape, and was checking my understanding of 'how things worked.}
The job _never_ got to step #4
The log file showed a bunch of strange messages, that -nobody- (I took it to the help desk, asking "what's thin mean?") understood. The help desk would puzzle over the job output, look at the 4 punch-cards, look back at the log, say "*OH*!! that was when the system crashed, why don't you try running it again." so I did, when I next had a chance. *sigh*
Experimentation showed that it was the "rewind the tape" command, itself, that was crashing the system.

I think the 6600 had Burroughs beat -- it could *lie* to you in the core- dump of a program that aborted due to a hardware exception (e.g. address out-of-range, using an 'infinite' operand {result of 'n' divided by zero} or using an 'indefinite' operand {result of dividing zero -by- zero}).
i.e., the program attempted to perform that illegal operation, generated a hardware exception which triggered a core dump, and there was *NO* evidence in _any_ register of the 'illegal' data that triggered the exception.
The systems programmers, just for fun, handcrafted a small assembler-code program that triggered _all_three_ of the possible exceptions, _and_ entirely covered it's tracks in the core-dump.
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snipped-for-privacy@host122.r-bonomi.com (Robert Bonomi) writes:

The early BCD burroughs machines (medium systems) would do BCD math on BCD fields that contained 'undigits' (i.e. 1010b - 1111b); needless to say, the results were unusual. Later versions of the architecture would 'catch a cow' (report Undigit Arithmetic Exception) if such a thing was attempted.
scott
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I've known of a number of micro-processors whee the 'BCD' opcodes were usable on any hex nybbles. Yeah, results were *NOT* "intuitively obvious' when what you call 'undigits' were involved, but they -were- consistent -- at least within the same processor model.
The CDC 6000 series didn't have BCD math hardware, but *somebody* had worked out some magic incantations whereby you could do simple arithmetic (addition/subtraction) on character strings of digits. i.e. take words with the strings '0000012345' and '0000056789' in them, perform a binary addition operation on them, followed by the 'magic incantation' instructions, and end up with a word holding the string '0000069134'.
I also knew folks that had worked out some _very_ creative uses for the 'undigit' handling done by some specific microprocessor chips.

sounds like a 'no bull' attempt to me. :)
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On Tue, 13 Apr 2010 15:54:58 -0500, Robert Bonomi wrote:

The original Univac I had tape drives that maintained tension with springs and pulleys rather than vacuum columns. Those drives, as well as the vacuum column model that replaced them on Univac II, could read both forwards and backwards. There were 10 drives.
One of the programmers (no, not me) wrote a program that issued a write command, followed by a read backwards, followed by a skip a block. That sequence apparently exceeded the response of the strings and pulleys and they wound up in a heap at the bottom of the drive.
The resident (yep, 24 hours a day) CEs wouldn't believe him when he described the problem. So he wrote a little program to demonstrate the problem, called in the CEs, and ran the program, dumping *all 10* tape drives. He wasn't very popular with the CEs after that, but when he told them he had a problem, they listened :-).
I sometimes think all us old computer nerds should start a website and record all these stories before we all die and the stories are lost.
--
Intelligence is an experiment that failed - G. B. Shaw

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There is also the story about a university student who got the engineering plans for an IBM mainframe disk drive (one of the washing-machine-size units), _carefully_ calculated the mass involved, and wrote a channel program that consisted of 'seek to outermost track', pause, 'seek to innermost track', pause, and "repeat indefinitely". The 'pause' times were carefully calculated to the 'resonant frequency of the drive unit. Reportedly, the unit 'walked' almost *THREE*FEET* across the floor, _towards_the_operator_, before they managed to find and kill the offending task. I'm given to understand that the operators were 'a bit nervous' for some days thereafter.
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Robert Bonomi wrote:

I managed to knock a selectric style printer off its stand with a little unfortunate development code.
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must have been a rather flimsy stand -- the golf-ball mechanism wasn't that massive.
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Robert Bonomi wrote:

It was the standard table. The ball doesn't have much mass, but the carriage doing full returns against the stop as fast as possible makes a lot of noise and did the deed.
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Doug Winterburn wrote:

Here's the data sheet for the printer showing the stand:
http://tinyurl.com/y5b6zqc
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On 4/13/2010 6:37 PM, Larry Blanchard wrote:

The IBM-1130 used a 1-card IPL program that was normally used to fetch a resident supervisor image from disk, and I kept a stack of 'em on the console for convenience...
I also made a hobby of writing 1-card boot programs to do things like making a copy of the supervisor image in the last of three spare cylinders on the disk, restoring from same, copying card decks, gang-punching control cards... and a little program that would seek past the innermost track to nudge a little rubber bumper against the drive hub - repeatedly - to make a really nasty buzzing sound.
Not exactly sure how it happened to be on top of the stack of boot cards when our friendly FE came in to do scheduled PM. He grabbed a "joybuzzer" card to boot up the machine, and totally freaked out a second time when told "It does that sometimes". :)
He did take it more in stride the time he booted up the machine and the printer wasted a page to inform him that "Sometimes I feel like a motherless child"...
He did not take it so well when someone (caugh) patched the resident supervisor idle loop to do a WAIT when the machine was waiting for work (could be anything from an empty card reader hopper to the interval between card columns while actually reading a card). Seems like the runtime meter (from which IBM billed the school) stopped when the CPU was in a wait state. The school's billings had suddenly dropped mysteriously by 90% and the branch office manager was (very) upset about lost revenue. The FE really was friendly - he negotiated a "Wink, wink, nod, nod, promise not to share this with other customers and you can keep the 90% discount" agreement.
--
Morris Dovey
DeSoto Solar
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*snip*

*snip*
That's apparently how the Apple II drive worked. The stepper motor would seek inwards 40 times, ensuring the head was at track 0. That way, the drive didn't need any fancy track seeking electronics.
Puckdropper
--
Never teach your apprentice everything you know.

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wrote:

I once caused a 6500 to lock out every other job by 'printing' a dozen or so boxes of blank paper. :(
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On Mon, 12 Apr 2010 20:07:05 -0500, Robert Bonomi wrote:

There was a saying back in those days that the perfect computer would have CPU by CDC, peripherals by IBM, and software by GE.
--
Intelligence is an experiment that failed - G. B. Shaw

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GE? The Datanet 30?
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On Tue, 13 Apr 2010 01:36:54 -0700, LDosser wrote:

No, the 400 and 600 series - remember Multics? And the first Codasyl DBMS?
--
Intelligence is an experiment that failed - G. B. Shaw

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Maybe before my time.
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On Mon, 12 Apr 2010 20:07:05 -0500, snipped-for-privacy@host122.r-bonomi.com (Robert Bonomi) wrote:

That's not unusual at all. Subtraction *is* adding the negative (complement).
OTOH, the IBM 1620 was known as the CADET (Can't Add, Didn't Even Try). It had no ADD (or subtract) instruction at all, rather used an index into a lookup table in memory to add. Want a different operator? Overwrite the "ADD" lookup table, sometimes on purpose, even.

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In one of my CS classes, it was pointed out that ADD circuits are usually smaller and easier than SUBtract circuits, so they're used more often. That's what was so weird about the subtractor being used to emulate addition.
Puckdropper
--
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