All Questions
5,790
questions
-2
votes
0
answers
10
views
Searching an old horror detective game
There was a game that I played back in the 90's about a detective who was trying to solve a murder in a hotel. The scene kept changing from a normal hotel to a dilapidated horror one (not unlike the ...
- 1
4
votes
1
answer
216
views
How can I connect a PIA or VIA chip to the Apple IIc?
I have an early Apple IIc, model A2S4000 with the 342-0272 motherboard
and ROM 255. (I am considering upgrading the ROM, perhaps with a
switch that would let me switch between different ROM versions.)
...
- 316
7
votes
1
answer
292
views
How to read old Macintosh text files?
I hope this is an OK place to ask this question.
The Internet Archive has a Macintosh floppy image containing presets for an old E-mu synthesizer module. The page is here Proteus Preset Libraries
...
- 8,775
5
votes
1
answer
313
views
Was it possible to complete the third rotation in Killer Gorilla?
As a kid I played a lot of Killer Gorilla on the BBC micro. This game was a clone of Donkey Kong.
Like Donkey Kong it had four levels, which the game rotated through and on each rotation they got ...
- 20.6k
37
votes
9
answers
13k
views
Why was USB 1.0 incredibly slow even for its time?
USB 1.0 is from 1996 and has a transfer rate of up to 12 Mbps.
I think it's extremely slow even for its time. Because here are two similar standards from the same time which are much faster:
IEEE 802....
- 3,854
13
votes
2
answers
461
views
What is stored in IIgs BRAM?
What is stored in the IIgs BRAM? I'm going to replace my BRAM battery in a ROM 03 IIgs and that got me thinking about what is stored in BRAM. I know that date and time are stored, but not if all the ...
- 316
3
votes
2
answers
383
views
What was the first satellite data link that can properly be called an internet connection?
Scott Manley, in his second video about communication satellites, focusing on the 1963 Telstar 1, mentioned at 10:22:
(Telstar 1) could be used for telephones it could carry multiple circuits, it ...
- 21.6k
12
votes
1
answer
477
views
Why can SafeDisc disks be read faster if the game was opened before?
First of all I want to say I have the games in real and I am just making safety backups. The disks are old and tend to lose data.
I am using Alcohol 120 Retro edition and found something weird.
I have ...
- 213k
19
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-...
- 213k
10
votes
2
answers
1k
views
How to use all memory on an IBM PC with 8086
I'm developing software for the IBM PC with an 8086 processor. I want my program to use all available memory.
I know that I can use DOS int 21h function AH=48h to allocate all available conventional ...
- 1,043
9
votes
3
answers
2k
views
Is there a common convention to describe the encoding of a legacy text file?
For the purpose of this question, a legacy textfile contains characters in the range 0x20 through 0x7e, with each line terminated by an OS-specific combination of 0x0d and/or 0x0a; it might be ...
- 2,279
20
votes
10
answers
9k
views
Was there any computer since about 1960 without interrupt support?
The invention and spread of interrupts in the 1950s is reasonably well known but I am curious: were there any systems after which didn't support them?
- 219
34
votes
4
answers
5k
views
How widely was 0xDEADBEEF used as a placeholder, invalid value?
Inspired by some comments on the question "The history of the NULL pointer":-
There was a practice in the '70s to use the hexadecimal code 0xDEADBEEF to indicate an invalid value. This could be to ...
- 21.6k
5
votes
0
answers
202
views
Where can I find a schematic of the AT&T KBD 301?
Where can I find a schematic of the AT&T KBD 301?
I have an old AT&T 6300 (AT&T's rebrand of the Olivetti M24) but the keyboard (AT&T KBD 301) is not working.
Many of the keys do work ...
1
vote
0
answers
222
views
CD-ROM not recognized by Windows 98 Pentium 2 [closed]
I have a Windows 98 Pentium II computer which behaves strangely. Although the CD-ROM opens and closes, I can't see it in Device Manager or play music. I get message that there is no CD-ROM device ...
- 11
11
votes
6
answers
3k
views
What made the ENIAC "programmable"?
The ENIAC was the first programmable, electronic, general-purpose digital computer. However, it was programmed by "rewiring", and this is what I do not understand.
When we say "...
- 38.2k
28
votes
5
answers
5k
views
Why does the Z80 include the RLD and RRD instructions?
The Z80 has an instruction RLD, which apparently treats the lower 4 bits in the accumulator and the full 8 bits in (HL) as a twelve bit integer which it then rotates left by 4 bits. The carry flag ...
- 3,659
6
votes
1
answer
486
views
PC DOS E Editor (3.13v): "Not enough memory" error with a file of 1.65 MB and 40 320 lines, even with the /S switch
Using the E editor included with IBM PC DOS 7, I can't open a particular plain text file without encountering a "Not enough memory" error. The editor was invoked with the /S switch to make ...
- 2,107
63
votes
7
answers
18k
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?
- 34.7k
10
votes
1
answer
1k
views
How much memory did the PlayStation development kit have?
The PlayStation 1 had two megabytes of main memory, one megabyte of video memory and half a megabyte of audio memory. Squeezing everything to fit into these limits was one of the big challenges of ...
- 118k
10
votes
4
answers
3k
views
How did the Apple IIe convert to upper case?
TL;DR
How did the Apple IIe convert commands to upper case?
Background
I've been using the Virtual ][ emulator in Apple IIe mode (with an Apple IIe Enhanced ROM).
After getting the ELIZA code from ...
16
votes
2
answers
3k
views
Was bootloading from punch cards possible on System/370 machines?
I have been idly looking into how System 370 works, though mostly at software and VM/370 OS. As a part of the system generation process, one needs to use DMKDDR utility and others. So I was curious ...
- 213k
22
votes
10
answers
5k
views
Why did BASIC programs tend to READ a redundant copy of DATA?
Take for example this BASIC version of ELIZA which starts out (in lines 50–170) by a number of READ loops which copy DATA (lines 1340 and following) into a handful of arrays.
Isn't this rather ...
- 2,927
16
votes
1
answer
905
views
Why did the Atari 800 have a flying RF lead?
The Atari 800 had a nice range of output sockets: four joystick ports at the front:
Along the right hand side, a serial interface (SIO) port, an S-video type output, and a power jack socket:
...
- 3,505
1
vote
0
answers
152
views
Windows 3.11 in DOSBox-X says that “Your network adapter MS$NE2CLONE is not working properly” [closed]
I had networking working on Windows 3.11 previously, now I am getting the error "Your network adapter MS$NE2CLONE is not working properly". I tried reinstalling all the files, changing ...
- 21.6k
9
votes
0
answers
275
views
How did Citrix for Windows NT 3.1 work?
The design of both Windows 9x and Windows NT (before NT4) was based on the assumption that the OS/kernel is driving a single local graphical console session (this is visible today: Windows Server 2022’...
- 781
14
votes
2
answers
1k
views
How was Prince of Persia "better/faster" with RWTS18?
I was reading about Prince of Persia over at POP Code Review. In that article, the writer printed an interview with Roland Gustafsson, the inventor of RWTS18 copy protection for the Apple II series.
...
- 38.2k
10
votes
3
answers
849
views
How can I make the Microsoft C compiler for DOS emit a loop with an intermediate jump to continue?
I am trying to recreate the exact C source code from some 16bit DOS 8086 assembly generated by the MS C 5.0 compiler. After making some progress, I've hit a wall with the following code (annotated in ...
- 21.6k
8
votes
1
answer
608
views
How to make Microsoft C for MS-DOS emit an immediate-target far call into the data segment?
I am trying to recreate the C source code from some 16bit DOS 8086 assembly generated by the MS C 5.0 compiler. I've hit a wall with this far call instruction.
0000008D 9A2F0CB506 call 0x6b5:...
- 21.6k
20
votes
1
answer
2k
views
How can I set up the Microsoft C compiler to make it prefer immediate-mode push instructions?
I started a project to get a better understanding on how to compile a game for Windows 3.x. I tried to set up the build workflow so that it produce the byte-exact clone of a great open sourced Win16 ...
- 21.6k
3
votes
1
answer
230
views
How to remove ___EXPORTEDSTUB statement from a NE (Win16) program's MAP?
I started a project to get a better understanding on how to compile a game for Windows 3.x. I tried to set up the build workflow so that it produce the byte-exact clone of a great open sourced Win16 ...
- 21.6k
42
votes
5
answers
6k
views
Why did so many early microcomputers use the MOS 6502 and variants?
Quite a few successful early microcomputers used the MOS 6502 CPU. This included, but was not limited to, systems like the Apple I, Apple II, Commodore PET, and Ataris. A followup known as the MOS ...
- 219
7
votes
5
answers
1k
views
What can be done with a USR file on the Commodore 1541 disk drive?
The USR filetype on the Commodore VC 1541 disk drive is a less common sequential file that according to some book sources can be executed as a program directly on the drive. The drive has its own 6502 ...
- 291
8
votes
2
answers
978
views
Help understanding TAIPAN source code for the Apple II
I am trying to run the source code found at https://taipangame.com/BASIC.txt on Epple 2 (with Apple II+ roms) to eventually run on my own Apple II+, but the program keeps crashing.
First, I used a ...
- 20.6k
8
votes
2
answers
693
views
Sinclair's microdrive -- was it based on compact cassette technologies?
Recently I've also looked inside microdrive drives of Sinclair QL and inside microdrive cartridges for it.
The tape looked like a compact cassette tape cut longitudinally to a half width (which seems ...
- 273
3
votes
0
answers
131
views
Did any DOS 3.3 variants relocate start of BASIC?
A common annoyance when programming in BASIC on the Apple II is that 6K of BASIC storage area falls before the start of the first hires screen, with another big chunk of storage falling after it. On ...
- 34.7k
12
votes
1
answer
2k
views
Why are some soft switches on the Apple II only triggered with a write?
The Apple II uses memory mapped I/O and soft switches to do many things. One thing has confused me though: why are some soft switches only activated when written to?
For example, 80COLON ($C00D) and ...
- 213k
12
votes
0
answers
420
views
Is it possible to trap 387 FPU opcodes on a 287 connected to a 386?
The 8087 and 287 FPUs were designed before the IEEE 754 standard was released. Because of this, they contain some instructions which are not compliant with it. When the 387 was released in 1987, it ...
- 21.6k
11
votes
1
answer
337
views
How can I communicate with a Nintendo DS using the Download Play protocol?
Would it be possible to use a Nintendo DS's Download Play feature over the Internet? I don't have a ton of understanding of how the protocol works, but so far I'm pretty sure it uses a network of ...
- 18.5k
8
votes
2
answers
1k
views
What happens if an invalid opcode is executed on a 287/387 math coprocessor?
https://groups.google.com/g/comp.os.msdos.programmer/c/Lds3MJAgSl0/m/y8zfPt-bMskJ I assume that the 287/387 math coprocessors do not have the same illegal opcode exception that the 286/386 processors ...
- 213k
13
votes
2
answers
759
views
How is the ‘Coprocessor segment overrun’ exception supposed to be handled?
The Intel 80386 CPU didn't have an on-board x87 FPU (maybe with the exception of some non-Intel clones). It was, however, able to use either a 80287 or 80387 as an external FPU. When the x87 FPU ...
- 21.6k
14
votes
3
answers
2k
views
What was Sinclair's intention with the Microdrive?
The ZX Spectrum was announced with support for both standard cassette tapes and Sinclair's new Microdrive format -- although the latter wasn't released for another 17 months.
Given that the necessary ...
- 273
8
votes
1
answer
906
views
Using Sinclair ZX Microdrive is it possible to random access a text-file?
I wish to build a small database using Sinclair ZX Microdrive: one can think to create a text file using some simple BASIC. For simplicity let's say the record is 512 bytes in length, i.e. the same as ...
- 273
7
votes
1
answer
780
views
What is the oldest UNIX available for modern systems?
What is the oldest UNIX(-like) system that can be legally downloaded and run in a VM or emulator on a modern PC running Linux?
- 173
21
votes
1
answer
2k
views
Where did the lookup table in Entombed come from?
Entombed is an Atari 2600 game where you move through an infinite vertically-scrolling maze and try not to die. This maze is procedurally generated, with two bits from a PRNG (underlined) added each ...
- 38.2k
18
votes
4
answers
3k
views
Commodore 64 - any way to safely plug in a cartridge when the power is on?
Back in the early 1980s when my friends and I all had Commodore 64s, we all knew never to plug a cartridge in with the power on.
I once got a tape from someone with lots of utility programmes, one of ...
- 2,279
30
votes
2
answers
2k
views
Process model in early UNIX
I heard recently that the process model in very early variants of UNIX was quite a bit different to the fork/exec model used nowadays.
How did it differ from the current state?
- 4,594
9
votes
2
answers
572
views
Why did the COMX-35 video memory seem unreliable?
In my early days, many many years ago, one of the machines I managed to get my hands on was the COMX-35, a funky little machine based on the 1802 CPU.
I remember trying to develop some games for it ...
- 6,333
103
votes
6
answers
46k
views
Why did base64 win against uuencode?
From the the two methods of encoding 8-bit data as human-readable ASCII, for a time, uuencode format was more popular. USENET 'binaries' groups were filled with uuencoded posts with whatever goodies ...
- 103
31
votes
3
answers
6k
views
Does the video game Control (2019) depict a real computer system? What is it?
I was playing Remedy Entertainment's video game Control the other day. Inside the game world, I've come across several computers. (They all look extremely similar.) To me, it looks like some kind of ...
- 213k