New answers tagged mainframe
9
Wire Wrap as used in computers is simply a later development then the ENIAC or vacuum tubes in general (*1).
The Keller tools were first marketed in 1953 and it took a few more years until they made their way from telephone to computers. IBM might have been the first, around 1960, a bit before the /360 came which used it a lot.
*1 - In contrast, PCBs were ...
7
One of the biggest factors is that when you have a machine that requires 5,000,000 successful solder joints to function properly, you need to make sure that all of your solder joints are really really good. If 1 in 10,000 of your solder joints is subtly bad, that means that the first time you try to put everything together you will have 5000 bad solders and ...
3
Did any computers of that era, provide such a variant instruction?
Kind of, the /360 (1964) implemented a Test and Set (TS) instruction for process synchronisation. A byte addressed was read, tested for zero/not zero (*1) and written back with all bits set (X'FF'). This write back was done not by the CPU in a follow up write access, but by the memory ...
6
Yes. Sort of.
The KDF9 had an accumulator stack (the 'nesting store' or nest) which was mostly made of fast (1µs read, 1.5µs write) core - the top 3 elements were in fast registers, with 16 words of core underneath.
Arithmetic was done on the top elements of the nest, popping off operands and pushing the result in the usual manner. Though the top cells were ...
4
Here's a video about manufacturing UNIVAC 1108 (circa 1965, so a bit later but still illuminating). Notice how much is done by hand, even things like winding coils.
According to the University of Minnesota the UNIVAC division employed about 10,000 people.
Price list for some UNIVAC 1104 components (long page of text, search for "UNIVAC 1004 PRICE LIST&...
4
The documentation, possibly including a language's keywords and their descriptions, could be copyrighted. This is why Zilog Z80 assembly language is not compatible with or a strict superset of Intel 8080 assembly language; because, IIRC, Intel registered a copyright.
34
R&D stuff isn't manufactured (at first).
It's usually partially constructed, ripped up, and redone, multiple times, with long testing and debug cycles in between, with the payroll running up the tab the whole time. Tons (literally) of fried or used components and partial assemblies can go into the junk bin. This includes all the mechanical stuff as ...
2
A conventional flip flop requires the following:
Two inverting switching elements that will strongly pull their output in the direction opposite what's required to turn them on.
Two elements that can weakly pull the output of whichever switching element isn't on in the opposite direction.
Two elements that, in response to external stimuli, can pull those ...
1
Back in 1962, when I was in a class to learn machine "coding" on a Burrough's 205A, the first 6 instructions were hand entered with toggle switches on the actual computer rack. They were the "start up" instructions that made the 8 bit computer smart enough to read the paper tape accessory on the side of a KSR-33 teletype. The 205A had ...
14
So what was the other $478,000 spent on?
Paying people to design and build it would have been a fairly big component. People often underestimate the cost of labour, particularly if it is their own time. Also looking at the photos of it on wikipedia, there were a lot of components besides valves. There were racks and other cabinets and what looks like a ...
-1
I'm no historian, and this is not a valid answer. It is just that it cannot fix in a comment. But I don't see why punched card any better than fanfold tape.
Tape predates cards. Folded tape dates back to the 1920s(US1541201A).
Colossus tape reader reads at 5000 cps in the 1940s, doubled card readers.
Folded cards don't need rewinding or waste packaging ...
1
Reading a single punched card is not very difficult. You just need enough photodiodes or spring pins to sense all the rows in one column, and a mechanism to advance the card precisely from one column to the next. The tricky part is handling many cards in sequence, and keeping them in sequence in the output tray for later reuse.
IBM had already solved these ...
4
But I'm used to a flip-flop being made of six transistors, which suggests it would need six triodes,
Not really, a basic flip flop does not need 6 transistors. maybe there's a mix up with RAM cells? Two will do it quite fine (*1,*2). Similar the two triodes of a 6SN7 is all what's needed - well, plus two rather equal resistors between them and another two ...
4
Was it ever possible to take an actual existing punch card reader, and hack a connection to hook it up to a computer?
No, why? The existing tabulating machine was all about parallel processing.
Or was it the case that yes the existing cards could be reused, but to use them with computers required designing and building all new equipment?
No. Of course not....
1
As pointed out in the other answers, trying to "edit" paper tape directly is awkward.
One solution is to have a batch editor that reads an edit tape into memory, then use the batch edit commands to read a source tape and punch an edited tape, according to the edit commands. A second tape reader could be used to reduce memory requirements.
A more ...
1
Other reasons:
Economics. Making a long roll is more expensive than cards. Shipping cubes is more space efficient than cylinders. If one section of the tape is damaged, it can't be sent to customer, but if cards are damaged, such as with oil from cutting machine, just replace them with non-damaged cards.
Structure: You can make a card stiffer, and it ...
4
There was paper tape and paper tape. For example, see Here for fan fold papertape. This could be read in by a conventional ASR33 type teletype reader but often was read by a specialized high speed reader. The fan folded tape could be fitted on one side and read through quickly. It could then be rewound almost like a tape from one side to the other. The first ...
3
Another advantage of cards over tape: Ease of setup for batch processing:
With cards, it is a trivial effort to pile up multiple stacks for successive scanning.
With tape, either you have to splice multiple tapes together in sequence and respool (a process fraught with peril of tearing), or dismount each tape and mount the next, which takes up a fair ...
2
A few additional side benefits of punched cards as opposed to punched paper tape:
Punched tape was supplied on rolls of particular lengths. A roll of
tape could only accommodate a certain amount of data. A stack of
cards could be any length.
Paper tape wasn't as robust as punched cards - the paper was thinner
than that used for cards. Punched cards were ...
11
Punch cards and paper tape are suited for different tasks.
Punch cards work better when the size of the data is not known in advance. How long would you manufacture the unpunched paper rolls? If the roll is too long, you are wasting paper and increasing costs. If the roll is too short, you either have to splice it together, or have the operator load more ...
39
Specifically concerning EISPACK. what happened was that James Hardy "Jim" Wilkinson in the UK (whose career as an applied mathematician started with practical ballistic modelling in WWII, working with Turing and other computing pioneers, and continued for the rest of his life at the UK National Physical Laboratory, not in some academic ivory tower) ...
7
An other nice thing about punch card is that you can use them, or better use a small pack of them, in another program. Some sort of copy/pasting.
I remember packs of hundrands cards with colored cards slipped from time to time to physically separate subprogrames that could be reused elsewhere.
9
What I'm wondering is: why punch cards instead of paper tape?
Because it was already there?
Early commercial computers were made to replace tabulating machines. To do so they had of course to be able to read (and write) punch cards. There was no need for paper tapes.
Well, ok, paper tape was first, as the Zuse machines used them and some other experimental ...
11
To add one more dimension to the answers already given: cards are easier to handle, whether by operators, or in a cafeteria (user self-service) system.
A high-speed card reader has an input hopper and an output stacker. After reading a deck of cards, you've got a deck of cards in the stacker.
The high-speed paper tape readers of my acquaintance would do ...
35
Punch cards long long long predated paper tape.
But there's a practical consideration you're not thinking of. If you had ever used punch cards and paper tape, you'd know:
Punch cards can be dropped, and they scatter on the floor. Then you pick them up, put them all face up (by the printing on them) in the same orientation (with the one corner that's cut ...
90
The basic issue that paper tape is hard to edit. In theory you can cut the existing tape and splice in a new section, but in practice there is no easy way to find the correct location except by printing the contents of the tape (at 10 characters per second) and searching by hand. People did learn to read the tape hole patterns (they were no harder to learn ...
15
The information to answer the question "exactly" is available on the internet, but I'm not going to do the arithmetic for you!
The Maintenance Manual (http://bitsavers.org/pdf/cdc/1604/033a_1604_Computer_Vol_3_Maintenance_Dec60.pdf) Appendix B gives the schematic of each printed circuit card, so you can count the number of transistors on each.
The ...
12
Make your way to Palo Alto, California, and find the Xerox PARC facility. Do whatever it takes to get a conversation with Alan Kay. Admittedly, you don't know any Smalltalk, but neither does anybody else. Your ability to think in terms of a collection of software objects interacting with each other will impress the hell out of him.
He'll get you a job ...
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