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Questions tagged [assembly]

For questions about Assembly Language in general. Also use the appropriate processor's tag.

53
votes
3answers
10k views

Why did DOS use dollar-terminated strings?

According to a few tutorials I am seeing, DOS used dollar-terminated strings to write to the terminal. This seems to also be documented here on INT 21H. AH = 09h - WRITE STRING TO STANDARD OUTPUT ...
0
votes
3answers
676 views

Does anyone have the source code of an early program written in Assembly? [closed]

I am interested in looking at the source code of any program that was written in Assembly just about when the Assembly language was invented. If anyone have a source code for such a program, please ...
48
votes
12answers
12k views

How was the first assembler for a new home computer platform written?

How did the 8-bit computers (Spectrum, Commodore, Atari, Amstrad etc) typically "bootstrap" from bare electronics into a platform with a working assembly language and OS? What I mean: An assembler is ...
32
votes
2answers
3k views

Why are first four x86 GPRs named in such unintuitive order?

On x86 the first four general-purpose registers are named AX, CX, DX, BX. It would be quite intuitive if their indices (those used in instruction encoding) were in alphabetical order, but instead of ...
52
votes
7answers
11k views

Why use static RAM addresses instead of the stack?

I'm studying the 65c816 assembly for the 1994 game, Super Metroid. A hobbyist studied the game in-depth and created a RAM map. From it: 7E:0B56 - 7E:0B57 Moves Samus this distance horizontally, ...
21
votes
5answers
2k views

How much benefit should be expected on a more advanced compiler for z80/r800 based computers?

I am self studying about compilers, and get hands on very good textbooks about the subject. I am thinking in develop a compiler using the almighty llvm infrastructure to cross compile to old computers,...
6
votes
2answers
971 views

Why the “jmp” instruction is not working?

I have written the following program in debug.exe: 1165:0100 mov ah, 09 1165:0102 mov dx, 107 1165:0105 int 21 1165:0107 db 'Hello World', 0A, 0D, '$' 1165:0115 jmp 1165:0100 However, when I ...
3
votes
1answer
180 views

What was the first publication documenting AT&T syntax assembly language?

What was the first publication to document what is (now) known as AT&T syntax assembly language?
11
votes
1answer
451 views

8080/8085 Instruction Test Suite

(This question was inspired by Comprehensive test suites for MOS 6520 PIA / 6522 VIA / 6526 CIA) Is there a comprehensive test suite for the Intel 808X series of processors? Something that would ...
8
votes
3answers
446 views

Arithmetic operations on multiple words on the PDP-8

For the PDP-8 with its strange ISA, I've always wondered what the "standard" (i.e. fastest) way to do arithmetic operations (add, subtract, maybe multiply) on integers consisting of multiple words was....