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9

About 0.6 to 1 ms after the last one is read. The 8042 keyboard controller does not queue scancodes; it just stops receiving bits from the keyboard until a byte is read from port 0x60. When a scancode byte is read out, the controller gets ready to receive another byte from the keyboard. But since serial communication is not instantaneous, actually receiving ...


9

[Caveat, this is from memory, and about a real PC-AT, with real, 16 bit BIOS and code] TL;DR: When does an IBM-compatible PC keyboard controller dequeue scancodes? (I assume this is about a PC-AT, not a PC or PC-XT) Never, as there is no queue. At least none in hardware. The 8042 has simply 4 registers Data In/Out, Status and Command. All synchronisation ...


1

Almost all these old machine did have SOME ventilation. The BBC seems to have less than normal, but there are some ventilation slots underneath, and on the back on some of them. That said, it does seem to have less than similar systems of the era. The fact is - those old 70s/80s home computers just didn't run as hot as modern Intel/AMD systems! Your typical ...


2

Did you try opening the drives up and giving them a good cleaning with isopropyl alcohol first? Sometimes the problems with old floppy drives is mechanical. Their step motors get stuck, or the lube on the screw drive dries out and the heads can't move. Make sure the heads are able to move with a little nudging. Clean them gently with a cotton swab. (Don't ...


5

Several sources around the web repeat the notion that the VT05 was a "drop-in replacement" for the (ASR33) teletype. For example, on gunkies.org: The VT05 Alphanumeric Display Terminal (technically, the VT05B, but documentation usually referred to it as the 'VT05') was one of DEC's first video terminals. It supported all the same format control ...


2

In the 1960s, many major languages such as FORTRAN and COBOL specified a line length of 72 characters. This was largely due to the limitations of the 80 column punch cards with which they had been originally programmed. An IBM punch card used 8 columns for a sequence number, leaving 72 to encode characters. This practical limitation was enshrined in the ...


12

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 the in-out bus, although it has no flags or interrupt capability. It contains A, B and C registers, which are loaded and read by the standard IO transfer ...


3

Modern heat sinks I assume this is about heat spreaders, as that is what they do. What is a reliable modern replacement Any one available at the usual stores will do it Which chips in the C64 and C128 should have such a heat sink installed? All may benefit, as they are NMOS and thus heating. Background It's about the surface size - larger surface to ...


8

If you want to know exactly how big the classic 1960s and 1970s IBM mainframes were, see the System/360 Physical Planning and System/370 Physical Planning guides. They give complete measurements of every part of the system. Consider the IBM System/360 Model 85, a large (but not the largest) mainframe from 1964. The processor itself took up 12 refrigerator-...


3

The hardware is modern enough such that to the best of my knowledge nothing would exclusively run on them but not on a current PC This statement partially answers your question, given that the idea of a "current PC" isn't frozen in time. 10 or 20 years hence, you may find it much more difficult to find a "current PC" that can utilize the ...


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