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Why does an instruction include the address of the next instruction on the IBM 650?

Very simple: Because there was room for an address and it improves performance a lot. Or as the manual puts it: It is important, however, for the programmer to realize that the simplest method of ...
Raffzahn's user avatar
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45 votes

Do the holes in Jacquard loom punched cards represent input data or program code?

Do the holes in Jacquard loom punched cards represent input data or program code? yes. Let me tell you a story. Somebody I used to work with many years ago was flying into the USA (or it might have ...
JeremyP's user avatar
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45 votes

Why did the IBM 650 use bi-quinary?

I will just explain what a bit is. It's a binary digit. 0 is numerically zero, 1 is numerically one. If you want to add 1 and 1, in binary it overflows. the result is 0, and a carry out. As you ...
Omar and Lorraine's user avatar
34 votes

How could early computers perform data operations before John von Neumann proposed the concept of ALU?

What von Neumann proposed was the idea of the ALU as a subsystem of an electronic computer, conceptually separate from the memory and input/output subsystems. The concept of hardware for doing ...
John Dallman's user avatar
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30 votes
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Why did the IBM 650 use bi-quinary?

Quibbling about the right meaning of "bit" aside, some advantages of the 2-of-7 biquinary representation are: Simpler circuits. In a quinary adder circuit, the output of each of the 5 output lines ...
hmakholm left over Monica's user avatar
25 votes
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Do we know the problems the University of Manchester's Transistor Computer was intended to solve?

Quoting the 50th anniversary page on the topic, In parallel to the Meg project it was decided to build a relatively small and economic computer. When design was started in 1952 it was clear that ...
Stephen Kitt's user avatar
23 votes

How were Zuse Z22 Instructions Encoded?

[Preface: this is about a very early architecture, defined way before and completely independently of today's canon, formed by IBM's /360. When reading, it might be useful to take terms used at their ...
Raffzahn's user avatar
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20 votes
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What is the difference between CTSS and ITS?

The technical differences are large when compared to the technical similarities. CTSS was built for a modified IBM 7094 system while ITS was built for the DEC PDP-6 (later PDP-10). Both of these ...
Walter Mitty's user avatar
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18 votes

Did this analogue computer from 1960 really have Internet?

No, this has nothing to do with any networks; the "INT" stands for "integrator." That panel and the adjacent one to the right are the interface to an integrator/memory module: Integrators in analogue ...
cjs's user avatar
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17 votes

Do the holes in Jacquard loom punched cards represent input data or program code?

Program code for modern CPUs, in practice, consists of opcodes which tell the CPU what operation to perform, and operands which provide data to operate on. In RISC CPUs these are necessarily both ...
Chromatix's user avatar
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17 votes
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How could early computers perform data operations before John von Neumann proposed the concept of ALU?

TL;DR: There seems to be a misconception between ALU as a box in high level discussion about computer structure and 'an' ALU as a concrete implementation of a logic to produce some calculative result. ...
Raffzahn's user avatar
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15 votes

Do the holes in Jacquard loom punched cards represent input data or program code?

All code is data. But not all data is code. For example, you can take a digital photo and the numbers represent light intensity across a 2D rectangle. Nobody would dispute that this is data but not ...
Artelius's user avatar
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14 votes
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Were any decimal-based computers capable of handling text?

Really early computers like the Mark I and ENIAC didn't have enough memory to attempt to handle text; also the use-case was mostly calculations. A number of decimal IBM computers used characters (with ...
dirkt's user avatar
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14 votes
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Why was ones-complement integers implemented?

[Please see this answer as well] Why was ones-complement integers implemented? Same question could be made about why decimal or other forms of representation were implemented - they seemed as a good ...
Raffzahn's user avatar
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14 votes
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What did Shin Nihon Kikaku (SNK) originally manufacture in 1973?

(For most parts taken from the Japanese Wiki) Eikichi Kawasaki operated a coffee shop and civil engineering business. When in 1973 asked to finance an electric engineering company of a friend, he ...
Raffzahn's user avatar
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13 votes
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What is the instruction set of the Z4?

Horst Zuse (Konrad Zuse's son, a computer science professor by trade) has a homepage where he supplies (and sells) various pieces of information, booklets and CDs and DVDs about his father's work. ...
tofro's user avatar
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12 votes
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Looking for help understanding a 'Reciproot' routine on the Manchester Mark I (1951)

Summary The reciproot code calculates the reciprocal of the root using the Taylor-Series expansion around x = 1, that is, 1/sqrt(1+ε) = ∑_{k=0} (-1)ᵏ (2k)! / (2ᵏk)!² εᵏ or 1 1 1⋅3 ...
dirkt's user avatar
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12 votes

What made the ENIAC "programmable"?

The ENIAC was the first programmable, electronic, general-purpose digital computer. A debatable claim, as each of those attributes (*1) is flawed in one way or another. When we say "programming ...
Raffzahn's user avatar
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11 votes

Do the holes in Jacquard loom punched cards represent input data or program code?

For most parts it's code. Well, code is a quite sloppy term, it covers a huge list of uses, from card scratching to encryption. So more correctly, it's a program (*1), as it defines a sequence of ...
Raffzahn's user avatar
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11 votes

Data length module of 3.2^n confusion in IBM system/360 architecture

The notation 3.2n looks to me like it means 3 x 2n rather than (3 point 2)n. So the question is whether data lengths should be based on a 6-bit unit or some 'binary' size, in practice 8 bits. The ...
dave's user avatar
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11 votes

Are there any good resources on emulating/simulating early computing input/output?

You can have a look at how simh, which emulates quite a few computer systems that had punch cards, paper tape, magnetic tape, harddisks, floppy disks, printer and terminals, handle it. Basically most ...
dirkt's user avatar
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11 votes

When was a compiler first used to generate code to be placed in ROM?

SAGE Missile Defense System, 1957 SAGE was a system of computers used by NORAD from 1957 to the 1980s. The hardware was designed by MIT Lincoln Laboratory, derived from their Whirlwind I computer, ...
DrSheldon's user avatar
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11 votes

Source For V2/A4 Missile Analog Guidance Computer Schematic?

I've extracted a reasonably complete description and schematic from the document Das Gerät A4 Baureihe B Gerätbeschreibung (The A4 Device Series B Device Description) published by the Oberkommando des ...
cmholm's user avatar
  • 351
10 votes

Why does an instruction include the address of the next instruction on the IBM 650?

If your primary memory is not random access, in the sense that at any instant some addressed words will take longer than others to be read, then you can potentially improve performance by having each ...
dave's user avatar
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9 votes

Why does an instruction include the address of the next instruction on the IBM 650?

Yes, it WAS due to the fact that with a rotating drum memory, you wanted the next instruction to be at a location that was just about to come under the read/write heads rather than in the next ...
Jennifer's user avatar
  • 201
8 votes

What is the first (say early) use of switches (mechanical or electromechanical) for sake of processing (like automatic motor control)simple data?

The first recorded use of relays in process control computing is in a patent granted to John Saxby in 1856. A brief description is given here. They were used to control railway signalling. The '...
Chenmunka's user avatar
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8 votes
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What is the first (say early) use of switches (mechanical or electromechanical) for sake of processing (like automatic motor control)simple data?

Switches are intended for just turning ON or OFF the power supply by either closing or opening the circuit. Not really. Switches in process control are intended to sense a state. That the result and ...
Raffzahn's user avatar
  • 228k
8 votes

Do the holes in Jacquard loom punched cards represent input data or program code?

I think the other answers cover the topic pretty well, but allow me to ask a related question as food for thought: is the music roll of a player piano code or data? On the one hand, the piano just ...
Lawnmower Man's user avatar
8 votes
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Data length module of 3.2^n confusion in IBM system/360 architecture

Note that 3.2 is the square root of 10 rounded up to the closest value with one digit after the decimal. Thus, every other data length module will be slightly greater than a power of 10. Apparently ...
Leo B.'s user avatar
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7 votes

How did the Burroughs B5000/B5500 provide hardware support for implementing Algol's call-by-name?

Based on a reading of a document titled Operational Characteristics of the processors for the Burroughs B5000, and applying a lot of interpretation, it appears that thunks are compiled in a fairly ...
dave's user avatar
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