Questions tagged [cpu]
For questions relating to CPU - central processing unit
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Did the NES CPU save die area by omitting BCD?
The NES CPU was a copy of the 6502 with the BCD circuitry removed. As I understand it, this modification was motivated by a theory that BCD was the only part of the 6502 that was actually patented, so ...
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Why didn't CPUs multiplex address pins like DRAM?
An important innovation for dynamic RAM was multiplexing address lines, so a 2^N-bit chip only needs N/2 address pins, which helps keep cost down.
Why didn't CPUs match this?
Setting aside e.g. the ...
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Is there any DOS game before Quake era (1996) that makes heavy use of the FPU?
Quake was one of the earliest DOS games to show most gamers the importance of having a fast FPU to play with. Were there any other games (probably 3D) before Quake that started using the FPU?
For ...
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What is the most performant "32-bit only" x86 CPU? [closed]
I am thinking of building an era appropriate early/mid-2000s gaming PC. One requirement is that the CPU should not support x86-64 instruction set, only the 32-bit instructions can be used.
My guess is ...
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Did any CPUs have a special instruction for multiplying or dividing by ten?
I recall reading about a CPU from the 90s which had, in addition to normal integer multiply and divide instructions, also had a special set of instructions for multiplying and dividing by ten. Does ...
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What aspects of microprocessor ISAs have been patented?
A key objective of RISC-V was that every aspect of the ISA must be based on an expired patent. It was felt that this is the only truly reliable defense against patent lawsuits.
It is surprising that ...
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Did any 8-bit device ever merge a CPU core?
Looking at https://upload.wikimedia.org/wikipedia/commons/c/c1/Commodore-64-1541-Floppy-Drive-04.jpg I started thinking the following:
There are too many chips in that drive. It is crying out for a ...
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Which CPUs have implemented trap on signed integer overflow?
All mainstream microprocessors from the 4004 on, have implemented signed integer arithmetic with twos complement and silent wraparound on overflow (by which I mean that the CPU itself will not trap, ...
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What do the pins D0-D7 on the Intel 8080 exactly signify?
I am currently trying to create a FPGA styled simulator of the 8080 in C. I have a couple of questions regarding the D0-D7 pins. As far as I can see the D0-D7 lines are used in order to store data (a ...
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How could early computers perform data operations before John von Neumann proposed the concept of ALU?
According to Wikipedia, John von Neumann proposed the Arithmetic and Logic Unit concept in 1945.
Mathematician John von Neumann proposed the ALU concept in 1945 in a report on the foundations for a ...
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How much space did the 68000 registers take up?
The Motorola 68000 has 16 (somewhat) general-purpose registers of 32 bits each, a generous complement by the standards of its day. I would expect these to take a significant fraction of the die area. (...
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How could the Intel 4004 address 640 bytes if it was only 4-bit?
I am reading Computer Organization and Architecture, 10th ed. by William Stallings and I found this on page 26.
where it says the addressable memory of 4004 is 640 bytes.
But it appears that the ...
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Who designed the ALi M1386SX core?
The ALi M1386SX is a 386 compatible microprocessor. I believe it was released around 1995, rather late for a 386 but since it was targeted at the embedded market (e.g. word processors and point-of-...
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Is it possible to raise the frequency of command input to the processor in this way?
In the 70's and 80's RAM chips worked at a lower frequency than the CPU.
That is, the processor worked at a frequency higher than the RAM.
We have that the CPU cannot receive one instruction from the ...
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When were the RCA CDP1804, CDP1805, and CDP1806 introduced?
RCA produced follow ups to its 1802 CPU, the CDP1804, CDP1805, and CDP1806. What years did they become available to purchase in?
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