Questions tagged [architecture]

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44
votes
7answers
9k views

What was the rationale behind 36 bit computer architectures?

Was there some particular design theory or constraint that made a 36 bit word size attractive for early computers? As opposed to the various power-of-2 word sizes which seem to have won out?
2
votes
2answers
215 views

How exactly do all control signals in 6502 work?

I'm trying to make a 6502 replica in Logisim. I want to know what exactly each control signal in 6502, how the clock cycles work and additionally I would like to see an example of these control ...
5
votes
1answer
359 views

Were there any working computers using residue number systems?

Wikipedia says: A residue numeral system (RNS) is a numeral system representing integers by their values modulo several pairwise coprime integers called the moduli. Bit widths of each of those "...
3
votes
2answers
306 views

Can S-100 cards attach to the ZX machines?

S-100 was, as I understand, a very popular way to connect various computer equipment together in the past. Also, from what I understand, S-100 closely matches the same signals as the Intel 8080, as ...
2
votes
1answer
628 views

How does the SNES (Super Nintendo) calculate the address of a character?

The SNES has a PPU (Picture Processing Unit) which comprises VRAM, OAM (Object Attribute Memory), and CGRAM (Color Graphics/Palette RAM). These are used to represent tiles, tile maps; attributes for ...
23
votes
5answers
7k views

Why did ones' complement decline in popularity?

Many early computers use ones' complement to represent some kind of signed integer. Examples include the PDP-1, the CDC-6600, and many other popular computers. The C standard is obviously written ...
10
votes
2answers
751 views

What is the history of the PDP-11 MARK instruction?

The PDP-11 MARK instruction was intended to be used as part of the standard PDP-11 subroutine return convention. MARK facilitated the stack clean up procedures involved in subroutine exit. To use it, ...
7
votes
2answers
3k views

Was the IBM 5100 ever used for codebreaking?

There's a rumor that there's something embedded in the IBM 5100 which makes it useful for codebreaking. What is the legitimacy of that claim?
10
votes
1answer
468 views

Can we express the instructions to the Analytical Engine in terms of assembler or machine code?

On a recent trip to the London Science Museum I saw Babbage’s Analytical Engine. Apparently this had an ALU (or equivalent). I can build an ALU out of logic gates but I can’t conceptualise how to do ...
8
votes
3answers
255 views

What was the value of the HP/1000 repeated indirection capability?

The HP/1000 was considered like a 16-bit "expansion" of the 12-bit DEC PDP-8.  Its addressing mode for loads and stores similarly used pages, base page and current page, and allowed for ...
6
votes
2answers
290 views

Did any pre-microprocessor CPUs have a clock near the toggle speed of the logic ICs used?

This question is NOT about single chip CPUs, but such that were built from many SSI/MSI logic ICs or using a bitslice configuration. A 74F... or 74S... type TTL gate or flipflop, if you provide them ...
11
votes
3answers
2k views

What was the first CPU with exposed pipeline?

Quoting from Programming for Performance exercise: early versions of the MIPS processor had an "exposed pipeline" (that is, the assembly language programmer needed to know the latencies of ...