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Applesoft (pseudo) Random Numbers - alternatives?

What are the alternatives (with examples on how to implement) to Applesoft RND(1) command? I have read of people using a completely different algorithm by poking machine code stored in a DATA ...
user21656's user avatar
8 votes
4 answers
1k views

Booting from SD card on a Compaq LTE 4/75 – DOS 6 works, Windows 95 doesn't

I'm in the process of restoring an old Compaq LTE Elite 4/75 laptop, which was missing its hard drive, so I thought I'd try booting using an SD-to-IDE adapter. On my main workstation I created an ...
Dmitry Brant's user avatar
6 votes
1 answer
556 views

Where are the pullups for the Commodore 64 keyboard matrix lines?

I'm looking at the schematic and the Service Manual for the Commodore 64. I can't seem to find a schematic for the keyboard itself. It seems clear that the control port 1 joystick has normally open ...
cjs's user avatar
  • 26.7k
5 votes
4 answers
535 views

Cheapest type of Read-Only Memory allowing Random access before Year 1970

Back in the 50s and 60s people had: random access, read-write memories like Magnetic Cores. sequential access, read-write memories like Delay Lines and Magnetic Tapes. And: sequential access, write ...
Schezuk's user avatar
  • 3,754
3 votes
2 answers
1k views

Why did IBM 7030 or IBM 360 use byte and word addressing simultaneously

In 1950s machines had a 36 bit words. And in this word we could pack symbols using 6 bits. And to fetch this symbols from the word programmer should do it using bit manipulations. In 1961 IBM released ...
No Name QA's user avatar
0 votes
3 answers
389 views

The earliest a home-computer or home-robot could be interfaced with a commercially available camera?

What was the earliest date a home-computer or home-robot could be interfaced with a commercially available tv-camera or digital-camera . Although I'm asking this question for the purpose of computer-...
typingcomputers's user avatar
185 votes
4 answers
46k views

What algorithm did Microsoft use to dither colour in early versions of Windows?

In the late 1980s to mid 1990s, most consumer-class video hardware was not capable of displaying greater than 16 colours at a time. To create the illusion of greater colour, software often "blended" ...
Mike Nielsen's user avatar
  • 2,897
85 votes
18 answers
19k views

Why was BASIC built into so many operating systems?

There are a lot of retro-computers with BASIC as an integral part of the operating system. The IBM 5100 was one of the first computers with a separate memory space for BASIC, followed by the Commodore ...
wizzwizz4's user avatar
  • 18.7k
83 votes
3 answers
22k views

Why does the Minus World exist?

In Super Mario Bros. for the NES and Famicom there exists a secret world, accessible by clipping through a wall to the first warp zone and entering the left-most pipe. This pipe will take you to ...
wizzwizz4's user avatar
  • 18.7k
73 votes
3 answers
6k views

Why was the return key symbol ↵ drawn differently from the motion of a CR-LF?

In the operating system (DOS) of IBM PCs, newlines were represented by a carriage return (CR) character, followed by a line feed (LF) character. The motion of a printer or teletype receiving such a ...
DrSheldon's user avatar
  • 16.3k
72 votes
3 answers
14k 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 ...
Evan Carroll's user avatar
  • 3,388
71 votes
3 answers
10k views

Why did Unix use slash as the directory separator?

The Unix designers came from the GE/MIT Multics project, and Multics inspired some Unix features. In particular, Multics has a hierarchical filesystem, and so does Unix. On Multics, pathnames were of ...
Barmar's user avatar
  • 2,370
67 votes
1 answer
11k views

What's the story behind the name "X11"?

To this day on Linux configs and startup scripts for the GUI system are stored in /etc/X11. I remember this name appearing alone, or alongside others - XFree86, X.org, X - for as long as I had contact ...
SF.'s user avatar
  • 7,115
66 votes
1 answer
5k views

How do I extract the program from the Radiohead "Nude" tribute by James Houston?

One of my favorite videos ever is a tribute to Radiohead "Nude" by James Houston. I have never seen the program in the video available to download, so I've just made an attempt to extract it ...
terrorrussia-keeps-killing's user avatar
64 votes
2 answers
12k views

Why are a lot of monochrome computer monitors green?

In my perception, the most common color for monochrome computer monitors is green or white/grey, though I have seen orange monitors. Is this genuinely the case, and if so, is there a reason for it?
dwjohnston's user avatar
64 votes
1 answer
12k views

Why didn't Windows 98 need the "Starting Windows 98..." screen?

In Windows 95, when you start up your computer, you see this message: Starting Windows 95... But in Windows 98, this is replaced entirely by the boot logo. Was this just for a better appearance, or ...
no ai please's user avatar
  • 1,123
62 votes
7 answers
19k views

What did the 'turbo' button actually do?

I remember the computer I played Commander Keen on as a child had a turbo button that I was forbidden to touch, what did this button actually do?
Neil Meyer's user avatar
  • 6,869
60 votes
17 answers
20k views

Simplest system to create an emulator for

Next year I'm going to teach a 2-semester microprocessors class to third-year undergraduate EE students. In order to sign up for the class, students need to have completed programming and digital ...
swineone's user avatar
  • 733
56 votes
4 answers
10k views

Why did line printers have 132 columns?

From what I read, most line printers have 132 columns. Also, the VT-220 and presumably other terminals may be switched between 80 columns (that's a usual width) and 132 columns. As I recall, 80 ...
Omar and Lorraine's user avatar
56 votes
13 answers
10k views

What languages are better fit for generating efficient code for 8-bit CPU's than C?

I found Why do C to Z80 compilers produce poor code? very interesting as it pointed out that C (which was leveraged to be an abstraction of a CPU for porting Unix) was not a very easy language to ...
Thorbjørn Ravn Andersen's user avatar
52 votes
4 answers
12k views

What did the 8086 (and 8088) do upon encountering an illegal instruction?

Preface: This question does in part intersect with Use of undocumented opcodes, but targets especially the 8086 instruction handling. I was reading Tanenbaum's "Operating Systems, Design and ...
Joe D's user avatar
  • 631
52 votes
12 answers
11k views

What early home computers have more than one CPU, where both could be used by the programmer? [closed]

I am interested to know if any computers that are on-topic for this site had more than one CPU, where this plurality could be leveraged by a programmer. Some cases I don't so much care about: The ...
Omar and Lorraine's user avatar
51 votes
3 answers
16k views

What was Nintendo's Software Development Environment for NES Games?

(This question was inspired by my previous question What kind of software was used to develop Nintendo 64 titles?) The NES used a modified 6502 processor and most games were written in Assembly. ...
JAL's user avatar
  • 9,620
49 votes
5 answers
12k views

How did Atari lose money on home computers?

The answer recently posted to Did Atari make more money from arcade games or consoles? quotes a New York Times article from 1982 https://www.nytimes.com/1982/12/19/business/the-game-turns-serious-at-...
rwallace's user avatar
  • 62.4k
49 votes
2 answers
4k views

Did Windows NT 4 emulate x86 on non-Intel platforms?

I've been trying to find more information about non-Intel versions of Windows NT regarding x86 emulation but found very little about it. There is one sentence about it in the Wikipedia page but the ...
aybe's user avatar
  • 7,102
49 votes
9 answers
12k views

Why weren't bootable game disks ever common on the IBM PC?

While for other platforms of that era (primarily, Amiga), putting a game on a bootable disk was quite a normal practice, this approach never taken off on IBM PC. Why not? I do remember people having ...
DmytroL's user avatar
  • 2,172
49 votes
4 answers
5k views

Why do older computer cases turn yellow?

Why do plastic cases of old computers turn yellow? Is this yellowing a problem that has been solved in modern plastics?
CommonerG's user avatar
  • 713
48 votes
9 answers
14k views

Why did the IBM PC need a sound card?

The original IBM PC and later variants used an Intel 8253 or 8254 as a sound chip. Why did users add sound cards such as the Adlib or Sound Blaster. I remember voice output with programs like ...
jwzumwalt's user avatar
  • 4,479
48 votes
1 answer
6k views

Where and when did the `0x` convention for hexadecimal literals originate?

By the early 1980s, C was using 0x as a prefix to indicate integer literals expressed in hexadecimal, e.g., 0xCAFE. This did not exist in B as of 1972, though B did support octal integer literals via ...
cjs's user avatar
  • 26.7k
48 votes
4 answers
8k views

Why are first four x86 General Purpose Registers 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 ...
Ruslan's user avatar
  • 1,444
45 votes
4 answers
8k views

How did Woz write the Apple 1 BASIC before building the computer?

According to his 1984 interview with Byte magazine, Steve Wozniak created the BASIC for the Apple 1 computer before he actually built the computer: I sat down and wrote the BASIC first, and that took ...
DrSheldon's user avatar
  • 16.3k
44 votes
2 answers
7k views

How did Windows ME "cripple" DOS?

Windows ME includes the ability to create a bootable DOS floppy. This floppy contains versions of COMMAND.COM and IO.SYS that are "crippled" to remove real mode. This is done with only one changed ...
wizzwizz4's user avatar
  • 18.7k
43 votes
1 answer
8k views

What do the keys on this Symbolics Space Cadet keyboard do?

Old keyboards like the one below seem to have contributed a lot to the design of modern keyboards. So, obviously, some of the keys are familiar because they are on my own average (modern Windows and ...
Laurel's user avatar
  • 1,720
42 votes
17 answers
9k views

Is there any text to speech program that will run on an 8- or 16-bit CPU?

I'm wondering if any of the ancient 1980's style text to speech algorithms were saved from oblivion and are still available. It might be nice to hear that vintage sound like what appeared in War Games....
wudude's user avatar
  • 521
41 votes
4 answers
8k views

What's with the Atari 2600 colors on SECAM?

On this picture below you can see that the Atari 2600 graphics are rather colourful, and some games like Pitfall! I think use the many shades of each colour and have rather good graphics for the 2600. ...
Omar and Lorraine's user avatar
41 votes
5 answers
10k views

What determines the color of every 8th pixel on the Apple II?

On the Apple II there's an interesting way to add a little color to the bitmap, since the high bit selects the palette used for the three-and-a-half pixels represented by the byte. Like this: 0: Black,...
Omar and Lorraine's user avatar
41 votes
5 answers
6k views

What's the origin of process return status 0 meaning success?

Why, usually, does 0 mean success in process return status codes? When I worked at TANO Corp in New Orleans in the late 70s and early 80s, the convention there was the opposite: 1, true, was the "...
Richard T's user avatar
  • 857
41 votes
3 answers
6k views

80286 can switch from real mode to protected mode - but why not back?

It's been a while, but I've read in a system programming book that you could switch your Intel 80286 CPU from the normal real mode to a more powerful protected mode. I clearly remember that they said ...
Byte Commander's user avatar
38 votes
1 answer
4k views

How did the 8086 interface with the 8087 FPU coprocessor?

The 8087 has many instructions - too many, it seems, to be encoded as part of the 8086 instruction set. How did the Intel 8086 interface with an Intel 8087 FPU that a user added? Consider the ...
Jet Blue's user avatar
  • 2,005
37 votes
3 answers
6k views

What was the first programming language to support “operator chaining”?

The Python language has a neat feature: An expression like x < y <= z is interpreted, according to mathematical convention, as equivalent to x < y and y <= z. Operands are evaluated only ...
texdr.aft's user avatar
  • 3,617
36 votes
8 answers
10k views

Why were floppy disks invented after hard disks?

For those of us who grew up with personal computers in the 1970's or 1980's, the experience was a very gradual migration from floppy disks to hard disks as the primary persistent storage. So, based on ...
Brian H's user avatar
  • 60.8k
36 votes
4 answers
7k views

What was the IBM PC cost saving for using the 8088 vs 8086?

The decision to use the 8088, a version of the 8086 with the data bus restricted to 8 bits, in the original IBM PC, seems strange on the face of it, certainly hurt performance and intuitively shouldn'...
rwallace's user avatar
  • 62.4k
36 votes
6 answers
6k views

What was the purpose and history of the C64's special keys?

I never had a Commodore 64 but I've always been curious what the purpose and history of some of the special keys were. In particular: C= Run/Stop Clr/Home Restore I'm mostly used to the standard ...
bjb's user avatar
  • 16.4k
36 votes
6 answers
19k views

Why did Windows 95 crash the whole system but newer Windows only crashed programs?

Example situation. You are using a program in Windows 95 and screen goes blue only for you to restart the whole computer You are using a program in Windows 7 and the program stops responding only to ...
Delta Oscar Uniform's user avatar
35 votes
2 answers
2k views

What BBC Microcomputer features were requested specifically by BBC engineers?

When requirements for the BBC Microcomputer were developed as part of the BBC Computer Literacy Project, an outline specification was created by an independent consultant, the late John Coll. This ...
Mick's user avatar
  • 2,829
35 votes
4 answers
2k views

What API did the "math box" provide?

Some classic vector arcade games, such as Battlezone and Red Baron, were based on the 6502 CPU. The processor wasn't fast enough to do the 3D computations, so a co-processor commonly known as the "...
fadden's user avatar
  • 9,060
34 votes
7 answers
8k views

Are there vintage or historical bitmapped fonts available for non-commercial use?

I'm looking for a source for one or a few 1-bit black-or-white bitmapped fonts used in the past, available in a set of sizes. Current incarnations might be available for large LED displays, but those ...
uhoh's user avatar
  • 2,358
33 votes
8 answers
12k views

How exactly did Windows become the OS of the home PC?

As far as I understand it, the whole personal computing revolution that Microsoft Windows did was not entirely by its own design. Is it true that the Windows OS at its core was originally designed to ...
Neil Meyer's user avatar
  • 6,869
32 votes
3 answers
6k views

What is DRAM refresh and why is the weird Apple II video memory layout affected by it?

I've roughly known the concept for years, but never really understood it. Back in the day, two types of RAM typically used in home computers: static and dynamic RAM. Static RAM (SRAM) was apparently ...
bjb's user avatar
  • 16.4k
31 votes
3 answers
6k views

Why was the DOS clock device renamed from CLOCK into CLOCK$?

From the Wikipedia article on reserved device names ... and the CLOCK$ (still named CLOCK in some issues of MS-DOS 2.11) clock device were introduced with DOS 2.0, ... Why was is necessary to add a $...
Sep Roland's user avatar
  • 1,185

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