Questions tagged [ibm650]

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48
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4answers
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Why did the IBM 650 use bi-quinary?

The IBM 650, announced in 1953, was the world's first mass-produced computer. It represented numbers in decimal, which is understandable, both because it needed to work with exact money amounts, and ...
45
votes
10answers
10k views

Why did 1950s-60s computers have such wide words?

Modern general-purpose computers typically have a 64-bit word size, but looking back in time, we see narrower CPUs. In the early 80s, the 68000 dealt with 32-bit addresses but the ALU was only 16 bits ...
27
votes
3answers
4k views

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

The IBM 650 seems to be a load-store machine. One advantage of a load-store machine is that the instruction can be shorter because there's less pressure to pack more information into it. But the IBM ...
22
votes
1answer
1k views

When did the IBM 650 have a “Table lookup on Equal” instruction?

In 1959, Donald Knuth wrote an assembly program named SuperSoap for the IBM 650. Here is the manual, and here is a listing of the program (in SuperSoap assembly language). Quoting from the abstract: ...
5
votes
0answers
155 views

Why did the Burroughs 205 not use bi-quinary like the IBM 650?

The IBM 650, one of the first general-purpose digital computers, designed in the early fifties, used decimal digits with bi-quinary representation for reasons discussed here: Why did the IBM 650 use ...
4
votes
1answer
295 views

IBM 650 - how many logic gates?

How many logic gates did the IBM 650 have? I'm used to measuring the complexity of a CPU by transistor count, but the 650 was a vacuum tube machine; the number of tubes would also be an interesting ...