When adding or subtracting fractions, you need to find the least common multiple of the two denominators. That's an expensive operation, much more expensive than adding or subtracting floating points, ...

Look at the development: ROM = read-only memory = can only be read when on the board, programmed in the chip factory. PROM = programmable read-only memory = can be programmed with a special programmer,...

And if you go back further, e.g. to the ENIAC, you'll see a word size of 40 bits. And if you go back even further, to mechanical calculators, you'll see word sizes determined by the number of decimal ...

Besides the flags, and differences in cycle count, the more important difference is that JMP x uses the effective address of x, while MOV x,R7 uses the value at x. In other words, there's one level ...

Partial answer: This article describes one flavour in more detail: While the specific tasks a computer did varied according to need and her department, the majority of computing work involved three ...

It is feasible, but not in software, because software is not fast enough. But indeed, it would basically let "anyone" build machines by picking out digital versions of components which ...

Example 1 The PDP-8 had only 8 kinds of instructions, but one of them was "microcoded" operate command: Different bits in this command would turn on different operations, which could be combined. ...

If you look at the datasheet of a typical DRAM chip of this era, say the Mostek 4116, it indeed has a cycle time of 375ns, so you can't access it at more than 2.6 MHz. But don't confuse the clock ...

I did that all the time on the Apple II. The reason it worked was that some time was needed for the motor to spin up to the correct speed, and that the Disk II didn't really have an "eject" mechanism, ...

Remember that these systems (not only the Osborne 1) didn't have harddisks. Everything ran from floppies. So usually you had one floppy where the program was on, together with OS related files. And ...

If you go back a lot before the x86, this technique wasn't unusual at all. In fact, writing programs using printable letters and symbols was pretty much the norm for early computers, except that there ...

On early IBM PCs, all devices were conntected to the ISA Bus. You can read about how the bus worked in detail here, including timing diagrams. Basically, all devices were just wired together. Some ...

There were different models of the PDP-8, but most models (say, PDP-8/E) consisted of a number of rackmounted boxes, one of which you could call the CPU (or, compared to a modern PC, maybe the ...

If I recall correctly, there were lots of variations to implement this scheme. Besides embedding characters in the listing that would reboot, or clear the screen every so often, a particular one I ...

Somewhat of a guess:  The C64 always interleaved CPU and graphics RAM access (with additional graphics cycles if necessary), effectively accessing RAM at 2 MHz. Judging from the ANTIC Timing ...

No, there were no adapters for different floppies. Data was typically copied by serial port, if it was copied at all: Programs on some 8-bit computer (e.g. Apple II, Commodore 64) wouldn't run on an ...

The Olivetti P6060 had 8" floppy drives (two of them). About the size of a typewriter, and ran BASIC, so IMHO it qualifies as "Personal Computer". The Wikipedia page even describes it ...

In the Wikipedia article on Transmeta there's a good example for the Code Morphing process, taken from a PDF document (Wayback archived) with even more details: The operation of Transmeta's code ...

Quick shot, without looking it up in Visual 6502 (which would be the authorative option): Sign extend the branch offset (replicate MSB of offset), that will tell you the ALU input for the PC high ...

The SC/MP seems to have been designed right from the start with a 12 bit address bus and 4 additional "page" bits. To quote from p. 1-4 of the SC/MP Technical Description: The SC/MP chip has a 16-...

Yes, slot 7 is unique electrically. Pin 19 (SYNC) and pin 35 (COLOR REF) are only connected for slot 7. These signals where needed by the PAL encoder card, which is why this card only worked in slot 7....

The 6510 CPU used in the Commodore 64 has an additional built-in general purpose I/O port compared to the original 6502 CPU. Address $0000 controls the direction for each of the bits of this I/O port, ...

Silicon Graphics started to provide dedicated graphics terminals and workstations in the 80s. So the technology was definitely there, even for 3D. In 1991, they put this technology on a PC expansion ...

As Tommy wrote in the comment: There are two different RAM chips, one for even columns and one for odd columns. Both are read and latched in one cycle (ESD and OSD bus), and the latched output of each ...

If you compare the octal opcodes for the skip instructions, a bcd | ||| 7500 SMA = 111 101 000 000 7440 SZA = 111 100 100 000 7420 SNL = 111 100 010 000 ...

The ISO 7185 Pascal standard, section 6.4.3.5 "File-types", says (my emphasis): There shall be a file-type that is denoted by the required structured-type-identifier text. The structure of ...

Not a complete answer, but a bit of information from the manual (for several Novas including the 1200): The hardware multiply-divide option for the Nova is actually a peripheral device connected to ...

No, conversion to 16-sector format (and the necessary change from DOS 3.2 to DOS 3.3) was a consequence of Steven Wozniak realizing that he could get more capacity by tweaking the Apple II floppy ...

I can't answer the question "why doesn't the 6502/65C02 use the PC to do the indirection to execute JMP (abs)", but I can answer some of the other points. Visual6502 is the best site to find out ...

In the first phase of the boot process, the BIOS loads the first sector of the disk into memory and executes it. The code in this sector then uses the BIOS to load the code for the second phase, which ...