All Questions

From the comments on this question, the SAM on the Apple II seemed to use some proprietary hardware to produce the waveform. (I am not counting the option to produce a horrendous 1-bit PWM using the ...

Does anybody know how I can go from an analog RGB signal to a TTL RGBI signal? Is there a good circuit for this out there somewhere?

I got BMOW's floppy emulator and have been pulling a bunch of files from 30 year old floppies (which have a miraculously low rate of failure) onto my SD card. One of the things I wanted to copy was a ...

Recently I have been trying to compile CP/M 2.2 from source. When I try to assemble, everything works except for the instructions ADD A,M and SBC A,M, which the assembler returns a syntax error. I ...

When you power up a Commodore 64 you are greeted with a friendly message telling the user it has 38911 BASIC bytes free. 38,911 is one byte shy of a 38 KiB (1,024 * 38 = 38,912). What was the reason ...

I just came across this excellent article on cassette tape storage formats. One thing confuses me though... in the "all digital" examples, like Figure 1C, what exactly ends up on the tape? That is, ...

I have a IIgs that I clipped the battery out of a few years back. I'm thinking I want to replace a battery in there, but before I spend money on a product like this one, I'm trying to figure out if I ...

Back in the DOS days of gaming (more specifically, 80286 - 80486 era), developers typically needed to choose between using the chunky and easier Mode 13h or the more complex "Mode X" that provided ...

To improve "authenticity" of a mainframe simulator and for an additional nostalgic effect, I'd like to add sounds of a line printer to it. They should be similar enough to the original sounds for ...

The IBM 650 seems to be a load-store machine. One advantage of a load-store machine is that the instruction can be shorter because there's less pressure to pack more information into it. But the IBM ...

I just got burned by the 260 character path limitation in Windows. Why did Microsoft decided to limit paths to 3 characters for drive + 256 characters + 1 character for the terminator? Mac OS of the ...

I'm in the process of restocking a lost collection of retro machines, including a couple of A500s, a 500+ and 2 A2000s (rev 4.1 and 6) in various states of disrepair. For one of the 2000s I would ...

This feedback loop looks similar to a LFSR, however there are no registers present. It looks to be some kind of oscillator. There seem to be three inputs to this component, IXP10 (pin 111), STBE (pin ...

'Blue Magic: The People, Power and Politics Behind the IBM Personal Computer' is an excellent book, but it makes one claim I cannot quite make sense of. Page 13 of the hardback edition says: "Lowe ...

In 2001, Eyring Corporation released a 32-bit reconfigurable RTOS called EYRX. I remember downloading the documentation and programmer guide from their Web site. Strangely, no traces of that OS can be ...

The Hobbit is a Soviet computer which was built to be compatible with the ZX Spectrum, but with some extensions. For example it has more memory and can run CP/M. The Hobbit had favourable reviews in ...

My first earliest experiences with "large" computers were an HP-2100 and a sigma-7, using a teletype and punch cards/line printer respectively. I've stumbled upon an old image of a PDP-6 and PDP-6 ...

What was the first mainstream development toolchain that provided advanced debugging facilities? By "mainstream" I mean something that was available on home computers, not mainframes or super-...

I've read that the PCjr supports a 320x200 pixel mode with 16 colors. But what I can't seem to find is how much memory that takes, how it's organized (chars?) or where it's located in memory. I'm ...

Based the the specs I found for the TG16, it has 8 KB of RAM. I also found notes in the documentation of many opcodes that there is data stored in several "flags and switches" are these stored in RAM ...

Was there ever a case of a spreadsheet application introducing intentional floating-point errors when it detected that it had been pirated? Particularly errors that were small enough to go unnoticed ...

Am trying to run Latex + Emacs under DOS 5.0, and would currently seem to need long filenames. I have tried the DOSLFN driver but it prevents Emacs from running. I have 4 MB RAM in total. Is there ...

Before the formats of floating point numbers have been standardized in IEEE 754 in 1985, different vendors had used many different floating point formats, some of them listed on the Data Format and ...

How significant and pioneering was the TV Typewriter, in light of things like calculators with CRT's from 1964 and various other things? I recently read that the TV Typewriter established the standard ...

Many years ago I was watching the news when I saw someone on a Sun workstation controlling the display using an external input device consisting of a series of rotary dials. Turning them rotated and ...

During the 1980s, it was quite common to see unofficial ports of popular arcade games released on home computer systems. For instance, Acornsoft (the software division of Acorn Computers) released ...

I'm porting CP/M to a new/old machine (the Amstrad NC200 laptop). Running programs on it is no problem, but running interesting programs (i.e. WordStar, Turbo Pascal and Ladder) involves implementing ...

I was given a funny, obscure game for Mac sometime in the 1994 to 1996 timeframe. Unfortunately I have no idea what the game was called, but I'd like to track it down. The game, which was in color, ...

Transmeta Corporation produced the Transmeta Crusoe Processor architecture. (Transmeta was also famous for having Linus Torvalds work there at the time.) We can see from the wikipedia article that ...

Back when I had a ZX Spectrum 48K, I had a friend that had a 128K and we would swap games for the weekend from time to time. We did try and make duplicates of the tapes (yes, I know, but we were ten ...

In my loft there is a computer with no branding that needs a new CMOS battery, and one that has the branding 'Tri Data' which I can't find anywhere on the internet. It just shows a white screen as ...

I am going to buy an old iMac G3 Over the next couple of days/weeks, and I want to make sure that I am buying a system with no problems. I usually ask for the serial number and good pictures before ...

I don't really know if this is the correct place to ask this, if not let me know where I should. I would like to know if it would be possible to run Ngage games on an existing Symbian emulator. There ...

The first Apple PowerBook laptops were delivered in 3 versions in 1991: PowerBook 100, 140, and 170. These initial PowerBooks were overall a tremendous commercial success for Apple, and are regarded ...

Several ways exist to protect against the copying of games but, when CD-ROM games were first introduced, were there any measures taken by video game developers to prevent the copying of games?

As you probably know, in the technology world, smaller is generally considered to be better. Companies compete to make the most portable phone, or the smallest laptop, but apparently Nintendo didn't ...

I came across my old Zip drive and some Zip disks. I am curious what is on the disks, but my Windows system won't run them. Back in the day I thought that these would be the ultimate in archive ...

In (S)GML ancestor's IBM SCRIPT/VS, what does DSM stand for in macros DSMFIG, DSMLIST... ?

I recently discovered the Osborne 1 computer, and I noticed it had two floppy disc drives. What was the purpose of including two drives?

I currently have Apple Pascal (and Fortran, and PILOT) running on an Apple IIgs emulator on Windows. As near as I can tell, it's UCSD p-System II.something. I also have a DOS-hosted UCSD p-System, IV....

I am a computer science student. I mostly work with computers and I am really wondering about the layout of keys in a keyboard. It is comfortable and easy. My question is this: what is the basic ...

The way I understand it, Nintendo's engineers couldn't figure out how to design a disk system for the SNES, so they commissioned Sony to do it for them. Why would Nintendo do this if they already had ...

A robot I can't find information on. I noticed an article and or advertisement in 1985, in the main city-wide newspaper ('mercury') in the city where this robot-factory was located. (I don't have ...

Here is the Valvo 2650. (Also known by other names, in the UK as Signetics 2650). What struck me about this image is the amount of empty space! If you look at a modern-day chip, say a Skylake or ...

The Commodore 1541 disk drive and other IEC devices are self-contained computers. The operating system runs on the drive itself. This setup significantly improves the flexibility. As a side effect, if ...

I haven't been able to find an easily comprehensible description of the super hi-res, dithered 16-color, 640x200 mode of the Apple ][gs. I can tell from the references I did locate, this is a ...

The Apollo Guidance Computer, was built on RTL which apparently can let off a lot of heat, and deployed in environments where we cannot rely on convection to pull the heat away (not only in low ...

From what I understand, with floating point arithmetic, shifting values up and down is important, since a floating point value essentially is an equation like 2e×m. This supposition may be supported ...

I was prompted to ask this by another recent question about early Unix process structure. The more-or-less contemporaneous systems I'm aware of (built 1960s to 1970s) mostly gave you a software ...

I seem to recall from my high-school days that certain Apple ][ programs protected themselves from being listed and therefore modified. If you tried to do it, the machine would simply reboot. How ...