phuclv
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Have there been any instruction sets with an odd register width?
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30 votes

Below are some architectures with odd word sizes: Apollo Guidance Computer: 15-bit Autonetics D-37C Minuteman II Guidance Computer: 27-bit Electrologica X1, Electrologica X8: 27-bit Calcomp 900: 9-...

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Can I use a 2880 KiB ED floppy disk in a drive that uses the standard 1440 KiB HD disk?
3 votes

I can think of several solutions Run the software in a virtual machine with a virtual floppy disk image attached to it Just change the drive letter of some partition to A: or B: since I doubt that ...

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Did any computer use a 7-bit byte?
2 votes

The ADAU1701 is a 28-/56-bit DSP for audio processing. CHAR_BIT is probably 28 on that platform like most odd-sized DSPs but I'm not quite sure since I couldn't find its programming manual

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What "unusual" syntax assembly languages are/were there?
14 votes

SHARC and Blackfin architectures processors are said to have "rich algebraic assembly language syntax" and are unsual in their own way. The syntax is somewhat C-like #ifdef INCLUDE_BUFFER3 .VAR ...

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Were there any 8-bit CPUs with 24-bit addressing?
11 votes

Yes. AVR microcontrollers with more than 64KB of memory do have 24-bit addressing. They have some additional registers for that purpose RAMPX, RAMPY, RAMPZ, RAMPD and EIND: 8-bit segment ...

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Where did the free parameters of IEEE 754 come from?
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60 votes

From an interview with Dr. William Kahan, the IEEE-754 formats were based on the VAX F and G formats, which have 8 and 11-bit exponents respectively. In fact Dr. Kahan also said that previously VAX ...

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Were there ever 12-, 24-, 48-, etc bit processors?
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34 votes

specifically after the 8-bit byte became the industry standard? There's no clear point of time where the 8-bit byte became a standard, since it's still just a de facto standard nowadays¹. However ...

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Have programming languages driven hardware development?
2 votes

Multi-operand IMUL on x86 Not quite sure if it was entirely driven by programming languages, but I believe they must have high influences to Intel's decision Originally there were only IMUL r/m16 and ...

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Why are different emulators needed to run platforms that use 6502 assembly code?
2 votes

Another important thing is cycle accuracy. Not every emulator is cycle-exact! What exactly is a cycle-accurate emulator? Emulation Accuracy Each emulator has a different level of accuracy. While it ...

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Which CPUs had instructions leaving data registers in an unspecified state?
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15 votes

There are a lot of instructions on x86 that leave the flag(s) in an indeterminate state, which means the whole FLAGS register is also undefined. Most will have AF undefined, for example TEST The ...

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Are PowerPC processors still manufactured and used in desktop computers?
4 votes

Are PowerPC processors still used in desktop/home computers, or has Intel processors taken over? If I wanted to get a PowerPC computer, is there a place I can still get them? They have pretty much ...

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Have programming languages driven hardware development?
9 votes

Another example is the decline of binary-coded decimal instructions In the past it was common for computers to be decimal or have instructions for decimal operations. For example x86 has AAM, AAD, AAA,...

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Have programming languages driven hardware development?
12 votes

Null-terminated strings When C was invented, many different string forms were in used at the same time. String operations were probably handled mostly in software, therefore people can use whatever ...

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Why was nil defined as a reserved word in Pascal?
5 votes

Because neither 0 nor false is a pointer. Pointers are pointers and not numeric values that can be used in directly in mathematical expressions. Assigning false to a pointer doesn't make any sense so ...

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