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7
votes
4answers
362 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 ...
7
votes
4answers
449 views

Is "component video" synonymous with "RGB"?

Before asking this, I read the Wikipedia article. I've been confused about this for many, many years. I'd like to finally get it straightened out. What exactly is the difference between "RGB"...
0
votes
1answer
191 views

Sony 9-Pin Protocol ("P2", RS-422) Help [closed]

I posted this in video production as well, but it's really more of an obscure serial thing: I have a modern SSD video recorder deck that inexplicably can only be remote controlled by RS-422 (Atomos ...
30
votes
6answers
6k views

Why did the monsters have "infinite invisible pillars" of hitboxes vertically in all versions of the DOOM engine?

Even in the last version of the DOOM engine, v1.9, used for Final DOOM, there is this strange limitation in which all the monsters have an invisible, infinitely tall "pillar" above and ...
16
votes
4answers
3k views

How were the special effects achieved for the Kraftwerk Die Roboter 1978 music video?

The following video for Kraftwerk's Die Roboter is very interesting because it features some effects which I think might require a framebuffer to achieve. Having a framebuffer in 1978 would to my ...
12
votes
1answer
1k views

What machine used POKE for printing?

I was looking through the Super Star Trek code when I noticed this for the first time: 7540 REM INPUT"DO YOU WANT A HARDCOPY? IS THE TTY ON (Y/N)";A$ 7542 REM IFA$="Y"THENPOKE1229,...
9
votes
1answer
390 views

Usage of Windows default 20-color palette

Currently I'm digging in the history of computer graphics and found the Windows default 20-color palette. It's based on the Windows and IBM OS/2 default 16-color palette but has the four additional ...
24
votes
13answers
9k views

Was there a technical advantage to such tall PC tower cases?

I saw a tweet today about what it claims is "the tallest PC case" which appears to have been made by SuperMicro: Further tweets in the thread include pictures of the inside of the case, ...
17
votes
3answers
4k views

How can I store a machine language program to disk on a C64?

I know I can use LOAD "PROGRAM",8,1 to load a program in a certain spot in memory, using the first two bytes of the file on disk. Now let's say I have used the .MON command on the Final ...
20
votes
1answer
2k views

How were the test registers used on the i386 and the i486?

The Intel 386 and 486 CPUs (and some clones too) had some test registers (TR3–TR7) which were used to test features like the TLB and caches. Starting with Pentium, these were replaced with MSRs (Model ...
8
votes
2answers
2k views

Why did the BIOS load the MBR at 0x7c00?

The IVT is at 0x0000-0x03ff while the BDA is at 0x0400-0x04ff but boot sectors are loaded at 0x7c00. What was at 0x0500-0x7bff that caused this convention? I'm also curious why some MBRs relocate ...
16
votes
3answers
1k views

6502 ORA not updating the accumulator

Unless I'm reading the manual incorrectly, the following should produce $11 when D404 = $10 (I'm turning on the gate for voice1 which has been previously set to triangle wave %00010000/$10) 00153 ...
15
votes
2answers
2k views

Porting use of BASIC to-the-power ^ operator

So I was porting one of the old BASIC games from the book "BASIC Computer Games", Ref: https://github.com/coding-horror/basic-computer-games to Python, just for fun. I came across the ...
41
votes
1answer
7k views

What's this computer in the 1988 movie "Vampire's Kiss"?

This is a grab from a 1988 movie called Vampire's Kiss. It has twin disk drives (5.25" from the looks) and what looks like a built-in printer?
11
votes
3answers
2k views

Name of MS-DOS program that shows realtime update of light/dark map of whole planet

Years ago (circa 1996-1997 maybe?) I ran a MS-DOS program that showed a map of the whole earth, updated once a minute with the time, timezones, and light/dark areas of the planet, taking up the whole ...
15
votes
2answers
1k views

How to use "AND," "OR," and "XOR" modes for VGA Drawing

I've been trying to implement a blitter in MS-DOS, but before I do that I wanted to test the various graphics modes of the VGA graphics card. (I'm emulating using DOSBox.) According to this paper on ...
10
votes
2answers
2k views

How did the CP1600 CPU supposedly make looping faster?

I came across an Intellivision in a box of stuff. When I looked it up on Wikipedia, it said that it uses a CP1600 that is based off a PDP-11. There's a weird entry on the wiki page: CP1600 did not ...
7
votes
1answer
111 views

Which versions of TECO had merged G- and Q-registers?

In this answer to 'Why were TECO variables called Q-registers?' I reference documentation indicating that the original Q-registers were separate from the same-named G-registers. (I.e., X1 would store ...
5
votes
2answers
370 views

Where can I find Windows 3.11 drivers for my Video Blaster capture card?

Where can I find a Windows 3.11 driver for a Creative Technologies CT6042 Video Blaster card? I need it to recover a piece of 90s era test equipment.
-2
votes
2answers
159 views

why the result comes out as 1, rather than 2, in this 8086 Subtract with borrow? [closed]

STC MOV AL, 5 SBB AL, 3 ; AL = 5 - 3 = 2, but I am getting 1 .. why? RET
19
votes
3answers
4k views

How does this 8080 code perform division with remainder?

Empirically, I've found that this routine (i8080) divides value from E by B and returns the result in D and E (result and remainder of division). divide_by_12_with_rest: MVI C, 9 ; @1 MOV A, D ; @...
5
votes
1answer
334 views

Apple II Assembly DSECT

I'm trying to define a section of data in a program. The Apple 6502 Assembler/Editor mentions an assembler directive called "DSECT" but I can't tell if I'm using it correctly or not. Here is ...
10
votes
6answers
2k views

How prevalent is the CR (classic MacOS) line ending today? [closed]

In a parser library I am maintaining, I stopped recognizing singular Carriage Return characters as line endings to reduce complexity in the tokenizer's position tracking code, a perennial source of ...
2
votes
2answers
351 views

Atari ST colour rendering

In the late 80's, I had an interesting incident with an Atari ST that I've never really understood. I was using some graphics software that I recall was very similar to the way Microsoft's Paint still ...
4
votes
1answer
431 views

What was the origin of sigils as an alternative to explicit type declarations?

Dartmouth BASIC seems to have gotten strings around 1968, and BASIC uses the $ on variable names to indicate that they're strings. This is a strategy for avoiding the need for explicit type ...
14
votes
1answer
2k views

Did any compilers hash long symbol names when truncating them?

Many early compilers and interpreters had maximum length for variable and function names. Usually you could use longer names but everything beyond e.g. the first 8 characters was discarded. This ...
25
votes
7answers
5k views

Why do variable names in BASIC need type suffixes?

The BASIC I'm most familiar with is Atari BASIC since I had an Atari 800 way back when. The Atari BASIC Source Book includes details about how Atari BASIC maintains variables. There is a Variable Name ...
32
votes
2answers
4k views

Which computer system defined the IPv4 576 byte datagram limit?

The IPv4 specification requires that IPv4 devices must be able to reassemble a datagram with a length of a minimum of 576 bytes. Looking back into the creation of the Internet... RFC 791 in defining ...
12
votes
1answer
750 views

What publication published an early version of the Apple Monitor by Woz?

This is driving me nuts. I am certain I have a downloaded scan of the source code to the 6502 ML monitor Woz wrote, but pre-dating Apple's use of the monitor. I even remember there was some text ...
7
votes
1answer
326 views

When was a compiler first used to generate code to be placed in ROM?

In the early days of compilers, it was expected that programs would generally be stored in an inexpensive medium (such as punched cards or magnetic tape) when not in use. Although it was possible to ...
5
votes
1answer
204 views

What CPU architecture was first to implement 'inverted borrow' carry flag during subtractions?

Background In two's complement arithmetics, if one wants to calculate a subtraction having only an adder that calculates {cout,result}=full_adder(arg1,arg2,cin), where cin and cout are incoming and ...
34
votes
3answers
5k views

Was the term "master" in source code management systems first used with the sense of master/replica or master/slave?

In recent years there has been a push by some to move away from using the term "master" in source code management systems, often by renaming the "master" branch to a "main&...
24
votes
2answers
3k views

Was leaving all xxxxxx11 opcodes unused on the 6502 a deliberate design choice?

The 6502, like many 8-bit processors, has a somewhat arcane opcode-mode restrictions. On most such processors, the restriction is a clear result of trying to pack a lot of instructions into a limited ...
26
votes
9answers
5k views

How common was programming in C targeting 8-bit processors in 1983?

How often was C used to program firmware for 8-bit processors in the early 80s? I'm reverse engineering a firmware binary for a device built around a Hitachi 6303 processor, manufactured in 1983. Even ...
8
votes
1answer
291 views

Raytheon 704 mini uses?

I came across this little machine in a roundabout fashion - 4kW of RAM and 1usec cycle for "under $10,000"! (not including ASR33) It seems this is largely lost to history. Does anyone know ...
12
votes
1answer
2k views

How can I enter BIOS setup on a Commodore PC 30-III?

I have a Commodore PC 30-III but I can't find a way to start the BIOS menu. It displays the following message during startup:
7
votes
2answers
221 views

How did Apple IIc daughtercard expansions work?

I've been doing a lot of reading about the ways Apple IIc owners expanded their machines in the absence of the IIe's slots, and it's very intriguing stuff. The ones that I'm most curious about are the ...
5
votes
1answer
198 views

What was the first control display unit with selector keys around the display?

If not the first, then the one that became popular first (in any application; this is not limited to aviation systems). A control display unit, CDU for short, is fairly common in aviation, perhaps ...
15
votes
5answers
2k views

Commodore Mouse not recognized by a Commodore PC30-III 286 machine

I have Commodore PC 30-III 286 machine with a serial port at the back labelled "mouse". If I plug my Commodore mouse 1900 serial mouse then execute mouse.com at the DOS prompt then I get the ...
11
votes
1answer
1k views

Is I/O port 0xFE reserved on the eZ80?

TL;DR Following on from OmarL's comment, to the closed question, Why did the Spectrum Next choose Z80 on FPGA?: But also, the eZ80 is not compatible with the ZX Spectrum because it uses port FE for ...
10
votes
0answers
173 views

Which versions of StuffIt introduced backwards-incompatible changes to the file format?

In order to help people who want to integration-test tools which shell out to The Unarchiver's lsar and unar utilities, I'm trying to build a legally clean repository of test archives in StuffIt SIT ...
9
votes
2answers
435 views

Cleaning buckling spring keyboards

How do you clean keyboards with buckling springs? I have mentioned in an earlier question that I've recently bought an IBM keyboard but how do you clean a keyboard with buckling springs? I only know ...
3
votes
1answer
257 views

Unicomp's IBM model keyboards

I've recently purchased the Spacesaver M Black Buckling Spring USB keyboard (still didn't get it due to shipping delays) and was wondering whether anyone has a real original IBM keyboard. What is so ...
9
votes
1answer
342 views

Can the TMS1802/0102, or specifically the Sinclair Executive calculator, handle an attempt to divide by zero?

There's a sort of urban legend among people I've spoken to about Sinclair that the Executive calculator can't divide by 0. Specifically, if you do this then it goes into a busy loop, cannot be used, ...
5
votes
1answer
213 views

Which early computer games supported "English" from the paddle controller?

In relation to this answer about the "English" control of the Magnavox Odyssey, I am wondering if the concept found its way into other games for later computers and consoles that supported ...
27
votes
3answers
3k views

Odyssey game console: what's the deal with "English Control"?

I've just read about the original Magnavox Odyssey console. Interesting story. But what I'm wondering about are the game controllers, and in particular the knob labeled as "English". This ...
29
votes
2answers
4k views

What is the Commodore 64C "France version" and why does it need a beefy resistor?

While perusing the schematics for the Commodore 64C (titled COMMODORE-64 B/NE) I came across a suspicious section of the power supply: The unregulated "9V" is connected to the completely ...
7
votes
1answer
210 views

Looking for a 90s Macintosh background pattern collection

I've been trying to find a collection of desktop patterns for Macintosh that I had for System 7 back in the day. I remember it as a specific application that you ran to set the patterns (as opposed to ...
2
votes
1answer
251 views

How to properly convert an active-low joystick routine to active-high

My last question wasn't specific enough so I'll rephrase it. I've been having trouble with programming game consoles/computers like Commodore 64 that have active-low joysticks, where the bits are all ...
18
votes
1answer
3k views

Arcade game: pseudo-3D flying down a Death-Star-like trench

I cannot find any references to this game so maybe someone here will recall it: It was a full-sized arcade cabinet with an aircraft-yoke type controller with fire buttons on the tip of the yoke. I ...

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