Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.

Questions tagged [microprocessor]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
31
votes
10answers
12k views

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

After seeing this question, I was struck with an intense curiosity to know: Were there ever processors with word sizes that aren't powers of two, specifically after the 8-bit byte became the industry ...
5
votes
2answers
231 views

Are there any CPUs or MCUs object-compatible with the 6800 that have additional index registers or addressing modes?

Having only a single index register and no addressing mode indexing against 16-bit addresses in memory seems to have been widely considered a primary reason that the Motorola 6800 fared poorly in ...
3
votes
3answers
235 views

Interrupt pin type on the 6502

I have a really basic question. I have to design an 65C02-based personal computer for a school project. I have to draw my own footprint for the 65C02. My question is what type of pin is the IRQB (...
3
votes
2answers
350 views

How does Game Boy / Sharp LR35902 HRAM work?

The Nintendo Game Boy has RAM called "HRAM" (meaning "high ram") decoded at locations $ff80 through $fffe. (All other decoded locations in the $ffxx page appear to be I/O device and system control ...
6
votes
1answer
333 views

Tannenbaum paper on constants in ISAs?

I see many references to a paper by Andrew Tanenbaum that demonstrated the vast majority of constants would fit into 13-bits, and I seem to recall it being in my university text on CPU design. However,...
2
votes
2answers
261 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 ...
3
votes
2answers
394 views

Total number of 6502s or 8051s ever manufactured or sold?

What's a good way to estimate the total number of 6502 or 8051 chips (or workalikes, pin-compatible or not, but not including software or FPGA emulators) ever manufactured or sold? Added: (To ...
12
votes
3answers
2k views

What was the first microprocessor to support full virtualization?

Virtual memory, which allows an operating system to run several machine code programs isolated from each other, came to the desktop during the eighties. But full virtualization, which lets the ...
15
votes
5answers
3k views

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

To my knowledge, an emulator turns machine code for a console into something that your computer can understand. For example, assembly code from a Gamecube game is not the same as from a .exe file. ...
2
votes
1answer
562 views

What is the difference between an 8080 and an 8051? [closed]

What are the features of the Intel 8051 architecture that allow it to successfully act as a microcontroller? Hypothetically can the general-purpose 8-bit architecture like Intel 8080 do everything the ...
16
votes
2answers
1k views

6502 branch offset calculation

This question expands on How does the 6502 implement its branch instructions? I'm working on a cycle accurate VHDL implementation on an FPGA. I have much of the program logic already written, but I ...
13
votes
8answers
3k views

Uses for the halt instruction?

What was the halt instruction in early CPUs such as the Z80 and 8080 used for? Here's a description of the Z80 instruction: The HALT instruction suspends CPU operation until a interrupt or reset ...
25
votes
5answers
5k views

How was microcode implemented in retro processors?

How was microcode implemented in retro processors such as the Z80 or 8080? Was the microcode standard (for example a manual for the processor outlining all possible micro-instructions and the ...
10
votes
1answer
510 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 ...
42
votes
5answers
15k views

Why did CPU designers in the 70s prioritize reducing pin count?

A lot of 70s era microprocessors were packaged in DIP packages with 40 pins. This was a reasonably good fit for 8-bit processors: 16 address lines, 8 data lines, 2 power and clock are all absolutely ...