All Questions

Filter by
Sorted by
Tagged with
-2
votes
1answer
39 views

Could visual inspection of the magnetic disk be used to detect the quality (or damages) of a floppy disk?

The magnetic floppy disk is sometimes used as an (infrared) light filter as shown on some pictures below. That led me to think about the actual magnetic disk and if inconsistencies or damaged could be ...
-1
votes
2answers
45 views

What do abnormal sounds or vibrations of a spinning floppy disk inside a floppy drive mean?

I saw this floppy drive sound emulator and this floppy disk sound video and wondered if the sound of a floppy drive or more specifically a the sound of a floppy disk spinning in the drive, could tell ...
6
votes
0answers
90 views

How did the PSP firmware 5.03 HEN-C exploit work?

On the historical PSP (PlayStation Portable) console on firmware version 5.03 there used to be a thumbnail-based exploit called HEN-C. It worked (under a race condition I presume since it didn't work ...
13
votes
2answers
3k views

Who invented small string optimization?

In the source code of the 1972 Pascal compiler (a very large OCR-ed PDF), there are declarations of variables and record fields of type ALFA, which are "packed arrays" of 10 characters. ...
4
votes
1answer
300 views

What was an Amiga "X-Drive"?

In computer magazine personal ads from the 1990s, I notice multiple mentions of Amigas "with X-Drive". Searching online, I find no mention of this. (Possibly this is because search engines ...
29
votes
1answer
2k views

How did the various Soviet ZX Spectrum clones support Cyrillic text?

There may be no one single answer to this question, since the various clones might have done this all in different ways. And of course, some clones do not have the Cyrillic text support at all. I'm ...
21
votes
4answers
7k views

Why are the Nintendo 64 memory cards' batteries *soldered* on?

After recently learning that it has a battery inside of it, I unscrewed my Controller Pak (N64 memory card) to put in a new battery. The old one says "98" on it, referring to 1998. So it's ...
2
votes
1answer
267 views

When was fixed page size, flexible assignment bank switching patented?

The 8-bit microprocessors invented in the seventies, had a 16-bit address space. It didn't take long for memory demand to exceed this, with the result that bank switching was a fact of life for the ...
9
votes
1answer
3k views

Approximately how many 3.5-inch floppy disks have been produced before manufacturing was stopped? [closed]

3.5-inch floppy disks are not produced anymore, with I think Sony being the last to stop manufacturing in March 2011. Meaning that all floppy disks that exist are currently in circulation and the ...
7
votes
1answer
381 views

What is the TPG file format used in the PlayStation release of Zork I?

I'm looking at the Japanese releases of Infocom games, curious to understand how the engine works. Four games were released for the PC98, one of which added graphics for the rooms (Moonmist). Later, ...
10
votes
2answers
647 views

How does the OPL2 Composite Sine Mode work?

The Yamaha YM3812 (aka OPL2) has an operation mode named composite sine mode (CSM), apparently designed for speech synthesis. Unfortunately I was unabled to find any documentation on what ...
5
votes
1answer
187 views

Z80 CPU and nested/reentrant NMI

According to multiple documentation sources, non-maskable interrupts (NMIs) can be nested (or reentrant) in a Z80 microprocessor. This is, upon a /NMI signal pulse, the CPU will interrupt the current ...
13
votes
1answer
211 views

"MOS" - Mini Operating System for PDP-11?

Around 1977 or so, I worked with MOS, a "mini" operating system for the PDP-11. I think it was originally developed at SRI, to support the BBN Packet Radio networking research. It was ...
4
votes
1answer
415 views

Why did this joke man page use July 16, 1974 as an epoch?

This fake manual page posted to the comp.humor newsgroup jokes that A.out accepts any option passed to it, stalls for a few seconds, and then prints a cryptic message chosen from the list below. The ...
14
votes
1answer
1k views

l-------l.com, a weird web page from 2000

I remember a mysterious web page from 2000 with the domain name l-------l.com. This domain name goes against RFC 5891 but it was valid back in the day. It's pretty hard to search for this. Most search ...
9
votes
2answers
292 views

What environment was Coherent developed with?

Coherent was a Unix clone for IBM compatibles Mark Williams Company produced and sold in the 1980s and early 1990s. What environment and tools was Coherent developed with? Was it cross-developed on ...
14
votes
2answers
3k views

Why are the magnetic floppy disk drives (FDD) heads not frictionless?

After reading this answer to the question How long can a floppy disk spin before wearing out? ... one could see thru the floppy... Not just badly worn, but the magnetic coating was outright polished ...
20
votes
5answers
3k views

How did old computers address far more than 64K of memory despite only having a 16 bit address bus?

I have an old Sharp PC-G830 pocket computer from the '80s that has 32K of RAM and 256K of ROM. I also have a simple single board computer I built with 128K of RAM and a few megabytes of ROM from a ...
4
votes
1answer
199 views

What information could be recovered from visualized magnetic information?

I was wondering how the data on a floppy disk physically looks like. With data stored on a magnetic disk obviously that isn't visible. The Wikipedia article on floppy disks however shows a beautiful ...
17
votes
5answers
2k views

How does a floppy drive identify the first and last sectors and tracks?

I've recently found a more modern application "Floppy Disk Master-7"(Picture 2) (FDM) that visualized the bad sectors, tracks and clusters(Picture 1) on a floppy disk in a similar (but ...
3
votes
1answer
82 views

What disk packs are compatible with the DEC RM05?

While the majority of DEC's PDP-11 systems used UNIBUS or QBUS based peripherals for storage, some of the larger PDP-11s, along with larger machines such as the DECsystem 20 and the VAX-11/780 used ...
10
votes
3answers
2k views

How good is this random number algorithm?

What follows are the random number generation routines from an ALGOL-60 computational math library, stored on a BESM-6 disk in a text form. The character encoding was with parity, imitating a punched ...
16
votes
1answer
1k views

What did memory dumps look like on 36-bit machines like PDP-10s?

I spend a lot of time looking at hex dumps of memory, which have a format that should be familiar to most: 00010000 00 FF 48 65 6c 6c 6f 20-77 6f 72 6c 64 21 00 00 ..Hello world!.. But on 36-bit ...
12
votes
3answers
2k views

Release timeline for 128KB personal computers?

IBM, Apple, Commodore, and Atari all released upgraded versions of their popular home/personal computers having "stock" 128KB of RAM around the early 1980's. What was the order of release (...
14
votes
1answer
1k views

What was the first Windows NT build to support Windows Registry?

The early alpha builds do not have a registry, thus I wonder what build was the first to include registry?
5
votes
3answers
239 views

What changes needed to be made to the Apple Desktop Bus to make it hot-swappable?

I recently came across a note in some hardware from late 80's that used an integrated Apple II something with ADB keyboard. It had a note that on that model, the keyboard was hot swappable along with ...
27
votes
2answers
7k views

Why did Nintendo name its console the "Famicom"?

The NES was known as the "Famicom" in Japan, short for "Family Computer". But why was it given an English name in Japan, given (I assume) most people wouldn't know what the words &...
4
votes
1answer
130 views

When did an overlay linker first appear in a PDP-11 UNIX OS?

On a 16-bit system with at most 64K of RAM available for a user program, one would think of having an executable overlay mechanism as an indispensable tool to maximize the amount of memory available ...
4
votes
0answers
271 views

Oddity in MS BASIC line lookup code on the 6502 [duplicate]

Does anyone know for sure why MS BASICs on the 6502 compared only the page number when deciding where to look for line numbers on branches? IIRC, it would only "start looking from here" if ...
48
votes
6answers
7k views

What is a Dumb Terminal?

There seems to be some confusion what a 'Dumb' terminal is as visible in answers and comments to this question about portable dumb terminals. So: What is a Dumb Terminal? Points that would help to ...
14
votes
1answer
1k views

What was the first two-panel file manager for DOS?

I'm trying to settle a debate between me and some colleagues about two-panel file managers in MS-DOS/PC DOS. According to my own recollection the first was DV.EXE (DualView IIRC), but some of my ...
2
votes
1answer
135 views

Does C64 /DMA assertion immediately disconnect the CPU from the address bus?

I have heard several claims (in the comments on this question and answers) that asserting the D̅M̅A̅ signal on the Commodore C64 cartridge port will immediately take the CPU off the bus by deasserting ...
23
votes
8answers
7k views

Why was computer memory so expensive and scarce?

Computer memory used to be a limited and expensive asset for a long while (for example, in computers with 16KiB RAM or less, compared to the 2 MiB of my first PC (an Intel 486) in 1995 and current day'...
28
votes
3answers
21k views

Why do Game Boy Colors not want nickel-cadmium batteries?

This is a page from the manual for the Game Boy Color: There is no explanation as to why this is, or how this can be, but it claims that one must not use rechargeable nickel-cadmium batteries. Why is ...
7
votes
2answers
638 views

Who introduced the standard 8-bit punched tape, and when?

Who introduced the standard that later became widespread for the 8-bit punch tape, and when? I think the 5-bit tape was an earlier standard.
10
votes
1answer
528 views

How did early Minix represent processes

Minix, as most know, is a "Unix-like" OS originally used for teaching. Early Minix (v1 and, apparently, v2) ran on the 8088/6 series of processors. It could run on the IBM XT. There have ...
2
votes
0answers
61 views

Apple II c repair keyboard and check disk driver error [closed]

I'm new in this forum and I want to say hello to all and sorry my bad English! I'm trying to repair an Apple II c computer that was stored in my house for many years. When I stored it, like 15 years ...
17
votes
8answers
3k views

Were there ever any dumb terminals in a portable form factor?

I’m curious if there was ever a case of a company making some sort of serial ASCII terminal, but in a portable factor, such as a laptop or even reasonable luggable. I’ve seen plenty of portable ...
1
vote
1answer
155 views

Transfer between bus and register in 6502 CPU

For one register of 6502 CPU (here X Index register) : If the SB/X (load) signal and X/SB (bus enable) signal are both asserted at the same time, what happens ? X Index register take the bus value ...
10
votes
2answers
321 views

Which plotter used these commands?

I've found a BESM-6 binary of a Pascal program which plots pretty pseudo-random pictures, like this A date is given as the seed for the RNG, in a "horoscope"-like fashion. After decompiling,...
28
votes
4answers
5k views

What are the "virtual machines" that were running on 80386 and later x86 CPUs before full hardware virtualization?

When reading techy articles about older Windows versions I often come across the term "Virtual machine". Apparently even Windows 3.11 had some sort of virtual-machine-thing going on in it, ...
25
votes
2answers
6k views

Strange version of Windows 3.1 marked with a "W" logo

I was digging through my storage and came across this old copy of Windows 3.1. It's a strange looking version though and am wondering if anyone has any info on it. The copyright page only mentions ...
16
votes
1answer
4k views

What kind of RAM stick is this?

Specifically, what are those two modules in the middle of each? I'm not too familiar with components this old. I've figured out that they're sticks of SEC SDRAM, but I've found nothing about any of ...
2
votes
2answers
196 views

How to determine the required RPM for a 3.5-inch floppy disk?

In addition to my other related question Is it possible to read floppy disks at non-standard rotation speeds (RPM)?. How to determine the required RPM for a 3.5-inch floppy disk as disks can ...
1
vote
2answers
209 views

Is it possible to read floppy disks at non-standard rotation speeds (RPM)?

According to this article 3.5-inch floppies rotate 300-600 times per minute (RPM). It is possible to overclock the RPM and will that result in higher transfer speeds? Or is it possible to read a disk ...
6
votes
0answers
297 views

Looking for an 8-bit microcomputer with a hardware-accelerated database

In some old video on YouTube a few years ago, I noticed a curious computer from the end of the 70s - early 80s. In the rack (half height), typical of minicomputers of those years, there was a 14" ...
13
votes
4answers
3k views

Which is the first non-assembly (and binary) language to write operating system(s)?

Many programming languages predating C, like FORTRAN, LISP, B, BCPL, were either special purpose or too heavy to write OS. OS were bound to their hardware architecture and died with them. C was used ...
7
votes
1answer
520 views

Hardware for higher resolution VESA modes

What computer hardware was needed to run something like Duke Nukem 3D smoothly at the 640x480 or 800x600 VESA modes at the time (1996-1997)? I was wondering if this was possible with contemporary ...
9
votes
1answer
185 views

What is the effect of direct exposure of the magnetic disk of a floppy to ultraviolet (UV) light?

I was thinking of the mold issue of floppies and UV light (UV-C) came to mind. As ultraviolet (UV) is a form of electromagnetic radiation and floppies use a magnetic disk for storage and I vaguely ...
5
votes
6answers
706 views

Amiga game about a detective or a spy in some kind of hotel building

There's a game I played as a young child in the 90s that I am 99% sure was on an Amiga. I've searched high and low and cannot find it, and am beginning to wonder if my memory is not accurate. I ...

15 30 50 per page
1
2 3 4 5
94