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1500 questions
34
votes
2 answers
On what computer did "JUMP" mean "don't jump?"
This question triggered a brain cell.
I remember a computer architecture, possibly one that was known for its beautifully symmetric instruction set, with an assortment of distinct mnemonics for different conditional branch instructions. All were of…
Solomon Slow
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6 answers
What type of interpreter were most 8-bit BASIC implementations?
I’m a big fan of early/mid 1980s personal computers like the Amstrad CPC, Commodore 64 and the Sinclair Spectrum. One thing these computers all had was a version of BASIC. Well known ones being MS-BASIC, Locomotive BASIC, etc.
As a language hacker…
Garry Pettet
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34
votes
4 answers
What exactly is a cycle-accurate emulator?
Emulators such as Higan are cycle-accurate and thus have full compatibility with all existing software. In a 2011 Ars Technica article, much was said about cycle accuracy and how it preserves games by allowing them to run flawlessly.
In the interest…
Matheus Moreira
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33
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2 answers
How did Elite on the NES work?
Elite was one of the earliest 3D games, wireframe only of course but still a remarkable accomplishment on 8-bit computers. Originating on the BBC micro, it was ported to many home computers, as well as the NES.
Wait a minute. The Nintendo was a tile…
rwallace
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33
votes
6 answers
Which was the first programming language that had data types?
Machine language (and Assembly language) don't have the concept of data types, so if you want to add an int and a float variables in Assembly, you have to use the appropriate Assembly instruction that adds an int and a float.
But if you are working…
user11869
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33
votes
2 answers
How many OS/2 viruses were there?
When I was in college, I remember IBM representatives trying to sell OS/2 Warp to students and teachers by saying that there were no (known) viruses for OS/2. (Of course, that didn't stop the makers of IBM AntiVirus for OS/2 and Norton AntiVirus…
JRN
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33
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7 answers
Last computer not to use octets / 8-bit bytes
I am old enough to remember computers that were not octet oriented. E.g. the first that I used was an ICL 4120. It had 24 bit words which were, when necessary, divided into four 6-bit characters. There were operations to support extracting the 6…
badjohn
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33
votes
18 answers
What were the real competitors to the early IBM PC?
As I understand it, PC was not really competitive with Home computers until the 90’s. The PCs rise in popularity in the 80s must have been mainly in the business world.
So during that time, what other options did people have for business computers?…
Johnathan
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33
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2 answers
Why was 2^127 − 1 an interesting problem for "Baby"?
The BBC News article The 'Baby' that ushered in modern computer age along with the short embedded video begins with:
A machine that took up an entire room at a laboratory in Manchester University ran its first program at 11am on 21 June 1948.
The…
uhoh
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33
votes
2 answers
Why was UNIX never backported to the PDP-7?
Originally, UNIX was written in PDP-7 assembly, and then in PDP-11 assembly, but then when UNIX V4 began to be re-written in C in 1973 and was run mostly on the PDP-11.
So far as I can tell, there is no Ancient C compiler that targets the PDP-7,…
Omar and Lorraine
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33
votes
2 answers
What is the relative code density of 8-bit microprocessors?
When RAM is at a premium, as it was in the old days, a greater code density of an instruction set can be a substantial advantage.
(Click saver: Code density refers loosely to how many microprocessor instructions it takes to perform a requested…
Leo B.
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33
votes
1 answer
How does the command.com shell work with MS-DOS?
On my systems that are running MS-DOS, I change the default command.com to 4DOS for more features.
How was the shell system designed and how did it with the operating system in MS-DOS that it enabled you to swap in a different one?
Thraka
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33
votes
6 answers
Dumping and archiving C64 disks
Doing spring cleaning with family, I found some old C64 disks. These are really old and no one knows what to do with them. Archiving or dumping them seems to be options but we are unsure how to do so efficiently and safely.
So, how do you archive…
Anthony Pham
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33
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4 answers
Did any MS-DOS program ever use the System Request interrupt?
As I remember, the SysRq key generated a special, unique interrupt (not an ordinary keyboard interrupt). It was supposed to let the user interrupt any process in a multitasking situation and return control to a special handler in the system. But, as…
Jess Fuckett
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33
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2 answers
Which BASIC-like language has "ENDIF", "DIM ... OF" to declare arrays, and a double slash for comments?
My mom found some old source code that she wrote for a course around the year 1983. I've tried to identify the language that is used, but have come up empty-handed. It seemed to be BASIC at first, but I haven't been able to find a version of BASIC…
tacecapS
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