Questions tagged [assembly]
Assembly languages in general, of any architecture. Use with the particular processor’s tag as appropriate.
254 questions
6votes
1answer
404views
Reading a key in MSX without blocking?
Turbo Pascal 3.3 for MSX apparently didn't didn't have graphics, sound or other useful functions to write games, however it allows inline machine code to be injected by using the reserved word "...
- 1,686
13votes
5answers
2kviews
Did any processor (ISA) ever exist which didn't have well-defined signed overflow?
The C language always labelled signed overflow/underflow of integers "undefined behavior". I usually argue and say that this is an artificial construct created by C. On the assembler level ...
- 994
10votes
0answers
376views
What is the "K09" referenced in MS-DOS sources? Is it the same as the IBM PC Convertible?
In the MS-DOS v4.00 sources (which I forked for lMS-DOS upon the 2024 April free software release) the msbio module has several references to a machine called "K09", for instance in https://...
- 1,539
14votes
3answers
2kviews
How to implement a bitwise AND operation in PDP-11 assembly?
PDP11 doesn't provide an AND instruction – just XOR. What is the usual PDP-11 assembly code to implement an AND, i.e. the PDP-11 assembler equivalent of the C code a & b please? What I'm looking ...
- 295
0votes
1answer
454views
Power PC G4 assembly language programming question
Edit: I suddenly realized that I can write a C Hello World and look at the disassembled code if I have the tool. I'll see what I get. I'm trying to write a simple Hello World program using an iBook G4 ...
7votes
3answers
1kviews
Fastest quasi-random function in 6502?
I am hacking around with the Oric Atmos computer, and it has an interesting video display scheme, involving attribute values which change the behaviour (ink/paper colours, blinking, invert) according ...
- 199
24votes
5answers
4kviews
Was it really possible to damage my VGA card by programming it in assembly through its latches registers?
During years 1987-1988, VGA cards appeared and replaced slowly EGA ones. But for some time, home developers hadn't a lot of knowledge about how to program them. The book "La Bible du Programmeur ...
9votes
1answer
570views
Is there a mistake in the code sample in “Programming the Z80” performing 16-bit by 8-bit division?
Programming the Z80 (3rd edition) has the following code sample (section 3 p.135) for division of a 16-bit dividend by an 8-bit divisor returning an 8-bit quotient in L and an 8 bit remainder in H: ...
- 193
5votes
2answers
732views
How to insert custom code into Super Mario Bros. NES file
I have a hobby project requiring adding some code to Super Mario Bros NES file. Specifically I want to display custom text (at least 22 letters and numbers, but more likely above 100 characters) after ...
- 181
2votes
1answer
555views
Did PCs ever actually have a halt instruction?
In the x86 computer architecture, HLT (halt) pauses the CPU until the next hardware interrupt occurs. So HLT doesn't really halt the computer; it pauses it. Was there ever a true x86 (or even /64) ...
5votes
1answer
361views
Apple IIe Enhanced not following BEQ correctly
I'm running the example code from Assembly Lines chapter 5 programs 2A and 2B which print the entire character map for the Apple II and then are supposed to break, however my code is looping ...
- 121
4votes
1answer
210views
View and modify active diskette parameter table
Machine is an AT 80286, drive A is 3.5' 1.44 Mb, drive B is 5.25' 1.2 Mb. Vector for int 1Eh is a far pointer to address of active DPT (diskette parameter table): -d 0000:0078 0000:0070 ...
- 489
16votes
2answers
2kviews
What is the origin of the many extra mnemonics in Manx Software Systems’ 8086 assembler?
While I was viewing the file AS.EXE, I stumbled upon next list of instruction mnemonics for the 8086 processor: ja jb jc je jg jl in jo jp js jz aaa daa aad adc add dec bge aam jae jbe lea clc bhi ...
- 1,365
22votes
10answers
7kviews
What happened to the job market for assembly programmers once high level languages became mainstream?
At some point it became easier and faster to write high level code than assembly. I'm curious about the transition - right now a full time assembly programmer is rare indeed, although there are still ...
- 3,727
0votes
2answers
229views
ASM as a DSL of a HLL? [closed]
There used to be a lot of discussion as regards embedding DSLs (Domain Specific Languages) into high-level languages (HLLs). The only example, where this is possible, I know of, is c++ and I had ...
- 827
