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What does an ADC (add with carry) instruction following ADD do?

I have found this line in an old 16-bit DOS application (likely to have been generated by Borland Turbo C compiler) and I want to understand the purpose of it: mov dx, [bp+var_192] mov ax, [bp+...
tigrou's user avatar
  • 689
16 votes
4 answers
2k views

How do I properly exit a program and return to the CCP in CP/M?

Once my CP/M program has finished doing whatever it's supposed to do, or the user chooses some sort of "quit" option, how do I return the user back to the CCP? Can I just do a ret? Or do I ...
cjs's user avatar
  • 26.8k
4 votes
0 answers
154 views

Name of application that showed cursor coordinates (both global and local)

There was a classic Macintosh shareware/freeware application - which may have been a CDEV/INIT (control panel or extension), DA (desk accessory), or an application - that displayed both the global and ...
Greenonline's user avatar
  • 4,396
17 votes
2 answers
3k views

What contemporary hardware was available for the development of Atari 2600 (or other 2nd gen) games?

The Atari 2600, along with others like the Odyssey 2 or Intellivision, were among the first programmable home game consoles. They existed alongside personal computers like the Apple II and Commodore ...
David's user avatar
  • 2,535
3 votes
1 answer
587 views

Why does this code trigger a TRAP on a PDP11/70?

On the PDP11/70, in the XXDP BKTCB0.BIC program I saw the following code: 012716 177777 mov #-1,(KSP) 006627 MTPI (PC)+ According to the comments in the source-code, this triggers a trap....
Folkert van Heusden's user avatar
0 votes
2 answers
785 views

What is the most performant "32-bit only" x86 CPU? [closed]

I am thinking of building an era appropriate early/mid-2000s gaming PC. One requirement is that the CPU should not support x86-64 instruction set, only the 32-bit instructions can be used. My guess is ...
tpimh's user avatar
  • 430
40 votes
4 answers
38k views

Did any processor implement an integer square root instruction?

Has any processor ever implemented an integer square root instruction? Obviously, floating-point square root instructions are quite common, but I've never seen one specifically for integers. One close ...
v-rob's user avatar
  • 857
5 votes
1 answer
1k views

What is an SS97 interface?

I happen to have a Siemens terminal, model S26361-K164-V1, and it seems its interface with the computer is not a more common RS-232, but something called SS97. I couldn't find much about it. It seems ...
rbanffy's user avatar
  • 543
5 votes
1 answer
714 views

Please identify this program for Acorn Archimedes

From the movie Murder Story This is the pc (is 90% Acorn Archimedes 305) This is the program another view Anyone recognize name of program? Thanks The os can be Arthur OS or RISC-OS
elbarna's user avatar
  • 2,341
3 votes
1 answer
369 views

Where can I find hardware details for the Philips VG-5000?

I'm interested in exactly what connectors the VG-5000 and what the pinouts are for them. Ideally, I'd like a full set of schematics for the machine.
cjs's user avatar
  • 26.8k
2 votes
1 answer
249 views

What was the 6502's reset behaviour when the RDY pin was low

How does an original 6502 behave if the ready pin is being held during a reset/power-on event? Would it pause CPU start-up entirely, delaying when some or all of the 6 internal cycles are executed? (...
David's user avatar
  • 2,535
-1 votes
1 answer
162 views

No mouse pointer in Enduro Racer [closed]

I run Hatari emulator on Linux with this cli hatari --disk-a /home/user/Enduro\ Racer\ \(1987\)\(Activision\)\[cr\ Axel\ Follet\].zip I see the game intro launching "enduro.prg" from a:\ ...
elbarna's user avatar
  • 2,341
10 votes
1 answer
2k views

Video game from the film “Murder Story” (1989)

From movie "Murder story" is from a console with small joystick anyone know the title?
elbarna's user avatar
  • 2,341
10 votes
2 answers
2k views

How does the sequence $C3, $C2, $CD translate to "CBM"?

I am fiddling with C64 cartridges and have successfully created one with a 32k EEPROM (of which I only use the top 8k). For the autoboot though, according to this source, I need to put the string ...
Bart Friederichs's user avatar
1 vote
1 answer
182 views

Setting email up on MacOS System 7

I recently got internet set up on my new Macintosh Color Classic and with a lot of hardship, set up the WebOne proxy, meaning I can load https websites. Most HTML 3+ websites still don't work in iCab, ...
gorgo's user avatar
  • 368
13 votes
4 answers
2k views

What were the most common software distribution formats for MacOS Classic?

What were the most common formats for distributing applications for System 6/7-era MacOS Classic? Were applications distributed on floppies/CDs or online/via FTP/via BBSs? And what format were ...
gorgo's user avatar
  • 368
9 votes
1 answer
471 views

What is a "driver information database" in Windows 9x?

At first boot post-installation or when installing third-party device drivers in Windows 95/98/ME, it's common to see the following dialog: So what is this "driver information database" ...
Fred Qian's user avatar
  • 304
1 vote
0 answers
114 views

Where to find datasheets for MOS (Commodore) 85xx chips?

It seems difficult to find any detailed technical information online for the 85xx chips used in later Commodore 8-bit computers. For example, there's an excellent archive at http://www.6502.org/...
Brian H's user avatar
  • 60.9k
10 votes
4 answers
2k views

oldest free assembler targeting the 386 CPU

What is the oldest free-to-use and royalty-free assembler targeting the Intel 80386 CPU in 32-bit protected mode, which knows all the instructions and addressing modes, and doesn't have obvious bugs? ...
pts's user avatar
  • 2,013
4 votes
1 answer
381 views

Is a version of TASM available for free?

Has any version of TASM (Turbo Assembler) been released for free by the copyright holder? I know that the following products have been released for free (available from here), but they don't contain ...
pts's user avatar
  • 2,013
8 votes
2 answers
1k views

Building a "hello, world!" program using MPW

I've been setting up a Basilisk II emulator to try my hand at developing apps for 68k System 7 systems, and have set up the Macintosh Programmer's Workstation (v.3.5 Gold Master from ...
gorgo's user avatar
  • 368
7 votes
0 answers
220 views

What was the title of this IBM PC software compendium book circa mid 80s?

Sometime in the mid 90s I stopped by a library that used to sell off their old stock and bought a copy of an IBM PC software compendium that I am now struggling to remember the name of or find ...
Noel Whitemore's user avatar
2 votes
0 answers
151 views

Using 386SWAT to trace a program through a transition from real mode into protected mode

The 386SWAT debugger seems to be able to continue tracing a real-mode (not V86) program that goes into protected mode, but I don't quite understand how to configure 386SWAT, and I can't find any ...
MRICHARD's user avatar
28 votes
3 answers
10k views

Was the MS-DOS window in Windows 95 an emulator like current DOSBox?

Windows 1.x, 2.x and 3.x required a DOS to be loaded before running them. Later Windows 9.x and ME had similar (?) way of working, but DOS was included with them, 32-bit multitasking and other stuff ...
matandked's user avatar
  • 383
16 votes
3 answers
3k views

Minimum game cartridge manufacturing time

I saw a remark in a documentary on the 1990s game console industry, The Story of the Nintendo 64 - Nintendo's Defiant Innovation - The Complete Deep Dive Story, that a key point that swayed third-...
rwallace's user avatar
  • 63.1k
18 votes
3 answers
4k views

Did the UNIVAC I really have a 2.25 MHz clock speed?

Wikipedia states that UNIVAC I "could perform about 1,905 operations per second running on a 2.25 MHz clock." (link) This claim is repeated basically all over the Internet. I find this clock ...
Jeroen's user avatar
  • 183
11 votes
2 answers
500 views

A kind of modem that let you make voice calls with a simultaneous data connection: what was it called?

I recall in the early 90s a type of modem (for analog phone lines) that let you conduct a voice call while maintaining a data connection. It sent bursts of data during the natural silences in ...
Tankboy's user avatar
  • 111
4 votes
1 answer
335 views

How to use external asm function in "vscode-amiga-debug" cross compiler?

I would like to write functions in assembly along with the c source code, but somehow I can't find the syntax. I tried e.g. in the fname.asm file (simplified): fill_bmap: rts In the fname.c ...
Tamás Putz's user avatar
2 votes
1 answer
358 views

Late 80s/early 90s matrix printer with a solid, curved front cover

I am trying to remember the exact year but I am drawing a blank. We had this matrix printer sometime between 1989 and 1994 in Hungary. What I distinctly remember is the front cover: it was solid, not ...
chx's user avatar
  • 1,041
1 vote
0 answers
184 views

Futuristic arcade spaceship game where your ship gains wings and wheels, collecting power-ups—from the late 80s/early 90s

Can anyone identify this game from the late 80s to the early 90s? What I remember about this game is that it had some very particular mechanics. For example, in some levels, your ship had wings, and ...
jose montalvo's user avatar
14 votes
1 answer
3k views

Historically speaking, why is man-db a separate package that is not part of the GNU project?

As far as I understand, GNU had a goal to create a completely free (libre) operating system, and to that end, created FOSS replacements for many UNIX programs. It puzzles me why they didn't try to ...
Kidburla's user avatar
  • 465
3 votes
3 answers
709 views

I want to use the line jack of a dial-up modem

Typically, an ISA dial-up modem card has two RJ11 jacks: one labeled Telco and the other labeled Line or Phone, intended to be connected to a telephone. Normally, when issuing commands to the modem to ...
Sung's user avatar
  • 509
5 votes
1 answer
246 views

Getting garbled text when using ADTPro with Apple IIc and serial connection

I am currently having issues while trying to use ADTPro to connect to my Apple IIc and was wondering whether anyone could help me. I am using this serial connection kit and trying to bootstrap from ...
Idrees's user avatar
  • 91
28 votes
5 answers
15k views

How did the Atari 2600 achieve a resolution of 160 x 192 pixels with only 128 bytes of memory?

According to wikipedia, the Atari 2600 had a resolution of 160 x 192 pixels. Had it been monochrome, it would had needed 160*192 = 30,720 bits of video RAM, or 3,840 bytes. But the total memory was ...
vakvakvak's user avatar
  • 391
3 votes
4 answers
652 views

Why is Z80 called a 8-bit CPU? [duplicate]

Z80 has a 16-bit address bus and 16-bit arithmetic instructions such as add hl,de. Why is it still called a 8-bit CPU?
xiaokaoy's user avatar
  • 141
1 vote
0 answers
222 views

ATX mainboard always on

I am moving my 6x86 system into an ATX case from an AT case. The mainboard is Amptron PM9800 supporting both AT and ATX power supply. As soon as I apply power on the power supply, the system turns on ...
Dercsár's user avatar
  • 695
40 votes
1 answer
5k views

Is it possible to know which lines in the Gameboy Color cartridge connection is missing by looking at the glitched Nintendo logo?

Context: I'm building a gameboy color flash cartridge based on the rp2040 mcu, I have came to the point where it displays an almost complete nintendo bootlogo at the startup. However, a few pixels(...
Ömer Gezer's user avatar
59 votes
2 answers
23k views

What is this large device labelled 'Telefunken Datenspeicher' and how does it work?

We found this device in our school. Does anyone know what this can do exactly, and how it could work? We managed to input values into the bit storage on the top, but nothing more. Can we calculate ...
Poldi's user avatar
  • 591
6 votes
0 answers
462 views

Why did only the TRS-80 see complaints about the screen?

Of the 1977 trinity, the PET and TRS-80 came with monitors built around black-and-white TV tubes, and the Apple II was commonly used with a black-and-white TV set. According to https://en.wikipedia....
rwallace's user avatar
  • 63.1k
3 votes
2 answers
259 views

Which S-100 systems supported both hard- and soft-sectored 8-inch floppies?

In the late 1970s to early 80s incompatible system software (i.e. MicroSoft Basic and CP/M 1.4) for S100 computers could be released in 8 inch, hard and soft sector, floppy disk formats. In that era ...
PDP11's user avatar
  • 710
0 votes
3 answers
587 views

XW8000 workstation boot from USB

I have an old XW8000 machine that I’ve been trying and failing boot from USB for the last week. I’ve tried burning Ubuntu 6.0, 8.0, 14.0, 22.04 on USB media using PowerIso and BalenaEtcher and the usb ...
Marcus 's user avatar
7 votes
2 answers
505 views

How did DRAM refresh work on the Altair 4K dynamic memory boards?

The initial memory board shipped with the Altair 8800 was a 1K board using one to four pairs of Intel 8101 1024 bit (256 × 4) static RAM. Altair then started working on a 4K dynamic memory board. The ...
cjs's user avatar
  • 26.8k
10 votes
3 answers
2k views

What were earliest attempts to make computers accessible? [closed]

Today, you have plenty of options: screen reader, magnifier, on-screen keyboard, etc. But how was the situation back then? Were there any options to make it easier for people with disabilities? Since ...
aybe's user avatar
  • 7,112
10 votes
5 answers
6k views

When did the PC bus start slowing access to video RAM?

The PC architecture, from the original IBM PC onward, has always been designed around the idea that video memory will be on an expansion card. This was an unusual design decision; most 80s computers ...
rwallace's user avatar
  • 63.1k
6 votes
1 answer
394 views

Can you write to the GDT on Windows 95 from protected mode? Why, and how?

Can you write to the GDT (Global Descriptor Table) on Windows 95 from protected mode? Why, and how? In some old notes of mine, I have: "In Windows 95 the descriptor tables are accessible from ...
AlphaCentauri's user avatar
15 votes
2 answers
1k views

Why is the addressing mode for BRK defined as "stack" in the W65C02S datasheet?

I most online documentation, I find the addressing mode for BRK to be "implied", which is logical. In the W65C02S datasheet however, it is set as "stack": Is there some reasoning ...
Bart Friederichs's user avatar
4 votes
1 answer
476 views

Is there an standardised 6502 assembly syntax?

I am working on a Flex/Bison based 6502 assembler (for fun and learning) and looking around for a "standard" syntax for the assembly language. Opcodes and addressing are more or less ...
Bart Friederichs's user avatar
7 votes
1 answer
526 views

Why is the Compaq FWS2ASPI.SYS driver not recognized as an ASPI driver?

I have a Compaq ProSignia server with an onboard NCR53c710 EISA SCSI controller. Compaq supplies a driver for it (the latest version is contained in the SoftPaq 10751 (SP10751.EXE), called FWS2ASPI....
Michael Karcher's user avatar
3 votes
0 answers
233 views

DEC (probably PDP-11) operating system with a guest mode allowing to run BASIC programs

In the mid 1970's I used an OS on DEC equipment (I believe PDP-11) that had a guest mode. If you weren't an authorised user you could login as guest mode where you supplied a name and if it didn't ...
hptsb's user avatar
  • 125
17 votes
1 answer
4k views

How did the AOL software provide internet access to other applications running on Windows 95/98?

During the late 1990s, I (and countless others) accessed the internet by running software provided by America Online (mailed to my house on free CD-ROMs) and using a dial-up modem to access their ...
smitelli's user avatar
  • 1,779

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