New answers tagged

5

Worthy of mention is the rise of the microprocessor- notably the 4004 which was designed for mostly numerical operation in calculators. Whether the step to 8 bit architecture was inevitable is open to debate, but once memory ICs started being produced in 8-bit forms, it would be difficult to justify anything other than 16-bit as the next step. Looking at ...


36

there some particular design theory or constraint that made a 32-bit word size attractive for IBM to migrate to? It all comes down to the most basic data type, addressing constrains and, less important, reuse of existing memory technology. The byte size had to be a multiple of 4, as needed to accommodate BCD numbers without wasting space. So 8 was chosen ...


6

One small reason is that you can access memory as a bit array without needing to divide (or do a modulo). Just use the bottom N bits for the byte or word or data cache line position or shift, and the rest of the bits left over as a memory address offset. Which can be done in hardware for free if needed.


3

Not sure I would trust 30 gauge wire wrap wire insulation with vacuum tube plate voltage. The cross-talk at the higher voltages plus digital edge speeds would also be far worse.


10

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 all over. *1 - In contrast, PCBs ...


20

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 ...


7

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 ...


7

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.


54

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, all the while with payroll running up the tab. Tons (literally) of fried or used components and partial assemblies can go into the junk bin. The specifications then often evolve with the ...


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 ...


2

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 ...


24

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 ...


9

If you want to read it as octal, having the low order 3 bits grouped together is handy. Many of the early ASCII tables showed the codes in octal. HEX makes more sense once your computers begin to work on 8 bit bytes, but earlier computers had units like 36 bit words that were divisible by 3, and this led people to use octal for a few years. Punched cards ...


-2

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 ...


5

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....


2

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 ...


2

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 ...


9

There were two issues, the first being that data entry was not interactive and data was often strangely formatted to get around the constraints of the 80 column punched card so the data wasn't easy to enter. An additional problem that not all punched card machines printed on the cards as holes were punched making verification harder. So type twice to verify ...


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 ...


4

Entering data twice squares the probability of a typo going undetected. Things have moved forward and these days we have the computing power to do some more comprehensive sanity checks ‘if (x = 0) { }’. I (just) missed the punched-card era but I’d say that pretty much as soon as a programmer was allowed to type commands directly into a computer they would ...


29

Maybe we don't always enter things twice, but verification is still a major part of software engineering. A lot of pure data entry is still done by double keying, which is to say, the data is entered twice by two different people and the results compared to try to reduce the error rate. As for programming, if you do it properly, there are code reviews and ...


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 ...


2

The MCS-51 family of microprocessors are post 8008 and do support a dedicated stack in hardware registers. Stack sizes of 128 and 256 bytes were common. As other people have said, it is very prone to stack overflow during interrupt handling. But also it is very awkward for RTOS support. For CPUs that support a stack pointer to some unique, external memory,...


12

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.


10

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 ...


37

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 ...


95

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 ...


1

The question mentions “early PCs” that generated a TV-compatible RF signal and “the color TVs of those days”. This would be a period spanning from at around mid-to-late 1970s to mid-1980s. The computer systems in question would be microcomputers aimed at the home market. By the late 1970s, new TV sets were already transistor-based and IC-based designs. ...


20

Many TV designs up into the 1970s were so called live chassis designs, which used one leg of the mains input as a reference ground. This saved materials and weight - given some early color TVs used 200+ watts at 100% duty cycle, you would have needed a rather bulky and heavy transformer, given that PSMPS technology was not really mature for consumer devices ...


10

TV manufacturers didn't have a single, obvious RGB connection standard to implement. Physically, there was SCART (with competing European and Japanese pinouts), RCA, DE-9, and various manufacturer-specific DIN plugs to choose from. Then you have the various electrical signals to send over them such as RGBS, RGsB, RGBHV, YPrPb, digital RGBI, etc. And VCRs ...


63

When colour television broadcasts began (1960s, in the UK; perhaps a little earlier in North America?) there weren't any local devices that customers might want to use. Broadcast TV was the only source of images that any home user could imagine. Adding extra circuitry to handle separated R, G, B and sync inputs (with appropriate protections against overload ...


21

Early colour TVs predated VCRs and home computers by many years. Even if it did not cost much, adding an RGB input would still be a cost for something that no one would use. However, it would have been more complex and expensive than you might expect today.


2

Regarding the last question, I've tried running Cyrus II on ZX Spectrum versus CuckooChess engine on android (droidfish app). If the engine was severely down-tuned, sometimes Cyrus II was winning.


3

The technique predated the modern combination of mice and graphical displays. Text terminals needed to show the cursor simultaneously with the character being highlighted by, or adjacent to, the cursor. Several very simple techniques for that have been employed, and inverted characters, also known as XOR, ended up as the most conspicuous and rather common ...


4

Really it was born out of neccesity. It was started in the days of monochrome displays. If your only colours are black or white then your options are somewhat limited. Back then, resolutions were not really good enough to have a white pixel and black pixel border around a white cursor like we have today. As colour displays became more common, the XOR mouse ...


-4

The name of the complete package (here a particular computer) has no relation to the name of the parts (here CPU). It may go as far as being legally risky to use the same name (moot if e.g. IBM or DEC did it with their CPUs and machines).


10

On systems without hardware sprites, this technique allows to avoid storing/redrawing the background without any backbuffer thanks to XOR properties. On the Amiga, on the other hand, the cursor is made with a hardware sprite. In that case, it's not possible to achieve the XOR effect, but the mouse move takes virtually no CPU. In that case, choosing a very ...


1

This is a "modern" chess program for the c64 that at least could be used as a framework maybe: https://github.com/StewBC/cc65-Chess


11

That makes me wonder if there was some reason for it other than individual preferences? Oh yes! Historically it even predates modern desktop systems, as the inverted mouse cursor was already part of the original Star design - as a UI feature for better usability. And it was/is really a necessary one. With an inverted 'inner' area, it offers maximum contrast ...


67

XORing a cursor into a frame buffer (which is what you seem to be calling "inverted cursor") is actually simpler than ORing it in there: when the cursor has to be removed again (to move to another position) you simply draw it a second time, with the same pixels, and it will vanish, courtesy of the XOR logic. If you have ORed the cursor into the ...


31

On Windows (1.x), at least, it's no more work to have this style of cursor than the normal sort. A Windows cursor is formed of two bitmaps: A mask that blanks out the shape of the cursor, and a pattern that is then drawn in the same place using the XOR operation. There are thus four possible combinations for any pixel: Mask bit Pattern bit Resulting pixel ...


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