Using relays to implement logic functions was already quite well understood at that time, and in fact the Post Office type relays were designed to do just that as part of the telephone system. The ...

Even though the CR usually goes before the LF in ASCII text, most printer mechanisms actually perform the LF before, or during, the CR. So the shape of the arrow is actually accurate. This is even ...

For the simple reason that until relatively recently, it was very difficult to make a rewritable optical medium, but it was easy to make a rewritable magnetic medium. Magnetic tape as a recording ...

For a start, it is widely known that FORTRAN II for the IBM 1401 series was specifically designed to generate high enough quality object code to make assembly programming of numerical routines ...

Internal power supplies, while not universal, were not unusual at the time. The major considerations were cost, ease of design, and safety (that is, passing safety regulations that already existed in ...

Every ship at sea carried such a human computer, in the person of the navigator. He followed a number of such "programs", properly termed algorithms, taken from Nathaniel Bowditch's seminal ...

Each of the 68K series CPUs had dedicated address-generation hardware which was wired more directly to the A registers and had only limited access to the D registers. Conversely, the main ALU was ...

You can actually try out these programs on a real-speed computer of that vintage using jsBeeb or, for a more convenient program editing environment, bbcmic.ro. To make the above programs compatible ...

Here is a reference to BIOS beep codes. For American Megatrends, look under AMI. 3 beeps means the low 64K failed - a very basic test - which probably means the RAM isn't working at all. You ...

DRAM requires that each row of the memory is read and re-written regularly, at least every few milliseconds for the devices available at the time the Apple II was designed. This contrasts with the ...

In scancode set 2, the "break" scancodes consist of the "make" scancodes prefixed by F0. This is consistent across nearly all the keys. Some keys include a modifier prefix in the Ex range as well, ...

The "programmer's switch" is more technically known as the NMI (Non Maskable Interrupt) switch. It is mapped to a priority 7 interrupt on the 68K CPU, which means it is capable of ...

It was common to install word processing software as a ROM into one of the spare "sideways ROM" sockets on the BBC Micro, in the same way as the DFS ROM needed to operate a floppy drive. ...

When you have a small transistor budget, it is considerably easier to design your circuitry around a single representation format - the most capable one - and treat converting other formats to and ...

In any BASIC variant that allows multiple statements on one line, the multiple statements that are required to implement a FOR-NEXT or REPEAT-UNTIL loop can be provided in immediate mode. Many 8-bit ...

Yes, part of the POST sequence (which occurs before the display lights up) is a simple memory test which also serves to detect how much RAM is present. The Mac then sets up the hardware and its ...

The letters A: and B: were reserved by MS-DOS, which was essentially a clone of CP/M and followed its usual practice, for floppy disk drives. If only one such drive was fitted, both letters were ...

Both keypads are in numerical order. However, in a computing context, the correct order is 0,1…9, but in a telephonic context, the correct order is 1…9,0 - because the latter is really a ten, not a ...

I think the best you could do in some cases was alter the pulse width of the basic square wave the hardware could produce. That wouldn't really change the volume, but you could make the tone "thinner"...

To directly answer the question: there is no difference whatsoever on the software side. The CPU core and indeed the die inside the package is exactly the same, just different pins are bonded out in ...

In more recent designs, since the mid-2000s I think, it became common to include "key" pins like this to reduce assembly errors. In most cases the pin removed was non-essential in the first ...

The so-called "1MHz bus" is not actually a separate bus. It is just the set of devices which were too slow to run at the full 2MHz in the original BBC Micro, and which therefore incur a ...

I don't have knowledge of the Rush 3D engine itself, but I used to work for a company that made software graphics engines, so I can speak in general terms about how they're likely to work. The GBA has ...

The tan(x) function has a period of π radians, with asymptotes at ±π/2; it effectively calculates sin(x)/cos(x), and the latter goes to zero at those points. So a function which evaluates properly ...

Hardware of this sort has to be able to cope with the worst-case scenario in any given dot-clock cycle. So it has to look at the top layer pixel, determine whether that is transparent, and if so go ...

Program code for modern CPUs, in practice, consists of opcodes which tell the CPU what operation to perform, and operands which provide data to operate on. In RISC CPUs these are necessarily both ...

Most PCI soundcards do not have hardware support for games and other applications that expect a SoundBlaster or AdLib to be present. Older cards made a special effort to provide what's known as "...

It sounds like some blocks on the disk (particularly the ones containing directory information) are okay, but some (containing some file data) are not. This is a data recovery situation. If you boot ...

It should be feasible to manufacture NMOS-process parts using 0.6µm equipment that is still in current use. WDC's W65C02S, as well as their other current products, are made at TSMC on 0.6µm, though ...

Most implementations of BASIC for 8-bit home computers were interpreters, and in that sense they're similar to the standard versions of Python. You could typically expect simple programs to run 100 ...