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Dartmouth BASIC array dimensions question

I'm trying to implement the CHANGE command from Dartmouth BASIC v4 and later. It allows you to convert a string into an array of numbers and back again. One key bit of the concept is that the length ...
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3 votes
2 answers
284 views

Asking explanation of 65C02 assembler code

From Gary B. Little's "Apple ProDOS: Advanced Features for Programmers", pages 176 - 188: "Since the ONLINE command handler is not inherently relocatable, all references to internal ...
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  • 41
2 votes
1 answer
121 views

When were Player/Missile graphics in Atari computers first documented?

The Atari 400 and 800 came out in 1979. The hardware included the ability to overlay sprites ("players" and the smaller "missiles") over the display. AFAIK, this capability is ...
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  • 1,098
4 votes
1 answer
167 views

SciTech's SVGAKit seems to be incomplete

I'm trying to get into MS-DOS development for fun, and I'd like to use SciTech's SVGAKit library. The last version of it is still downloadable via the Internet Archive here. However it seems to be ...
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  • 141
3 votes
3 answers
540 views

Z80: asymmetric use of B in DJNC (B is a low byte) vs. BC in LDIR (where B is a high byte)

Am I missing something or is Z80 weird in its use of the B and C registers? If I want to copy memory, I have this super cool LDIR instruction which copies (HL) to (DE) BC times and incrementing HL and ...
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-4 votes
2 answers
117 views

Can someone clear up principles of CPU caching and pipelining simply and precisely? [closed]

I am asking this here because from the history the principles might become much clearer than looking at the latest and greatest CPUs. Of course I know that "cache speeds up memory access" ...
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18 votes
3 answers
2k views

IBM PC Alt + numpad for entering character codes: firmware, BIOS or OS?

Back in the days of MS-DOS, when I needed to type a special character that wasn't part of the keyboard layout, I would press down the left Alt key and type out the character code on the numeric keypad ...
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  • 1,098
14 votes
3 answers
3k views

Z80 is making weird relative jump errors. How can that be?

My little Z80 breadboard project got stuck in the mud where I am pulling my hair out. It looks like the CPU is making a calculation error on a relative jump. Here is my code, and I don't think ZX ...
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4 votes
3 answers
190 views

Z80: can you transfer the program counter (PC) to a general register (e.g., HL)? [duplicate]

New to Z80, coming from 6502, the instruction set appears hugely CISCY. And yet, I cannot find a simple method to inspect the PC (transfer PC to a general purpose register, e.g., HL). I need this to ...
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10 votes
1 answer
2k views

What would you call the occupation of a person who changes vacuum tubes?

As the title states, what would be the job title of a vacuum tube replacer? Vacuum tube operator? Vacuum tube engineer? If your job had you spending most of your time replacing vacuum tubes, what ...
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4 votes
3 answers
1k views

CRT-Screen-Compact-Desktop-Calculators of the 60's, could versions of this tech have been made as word-processors or even video-games? [closed]

CRT-Screen-Compact-Desktop-Calculators of the 60's, could versions of this tech have been made as word-processors or even video-games? Word-Processors - How difficult would it have been to save what ...
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  • 177
26 votes
2 answers
3k views

What "spectacular to watch" algorithms were used for sorting tapes?

Python's heapq.__about__ variable contains an anecdote (François Pinard, circa 2000): [1] The disk balancing algorithms which are current, nowadays, are more annoying than clever, and this is a ...
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17 votes
2 answers
3k views

In 16-bit MS-DOS, how do I get a file handle to the currently running .exe?

The context is that I have additional data in the .exe file and wish to access it. I know this is possible, as plenty of programs would store extra data after the loadable part of an MZ .exe — most 32-...
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18 votes
3 answers
5k views

Windows 98 setup preparation hangs at 100%

I am trying to install Windows 98 on a pretty modern computer, from 2010. Why? Because I want to see if I can. Anyway, I am booting off a USB flash drive with FreeDOS on it. I formatted the USB flash ...
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6 votes
5 answers
417 views

Is there a CPU ISA preferring a test for the value of one over testing for zero?

While discussing a question about the origin of Zero as value for the default exit code for success, I reflected if there is any Instruction Set Architecture or implementation thereof where testing a ...
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