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56

SCSI, I think, is a serial interface. No, it isn't. SCSI das defined as a parallel interface for high speed data transfer. Though there are modern incarnations using serial transfer, while being compatible on a logical level, which might add confusion. A standard serial port on PCs used a 9-pin DSub connector where a parallel port used a 25-pin connector. ...


24

Early Wang basic computers used a backplane keyboard with an enormous bespoke parallel interface to the detached style keyboard device. Wang's 2200 and 2600 BASIC-only minicomputers were available with the 2215 BASIC keyword KBD, the 2222 alphanumeric typewriter KBD, and the 2223 upper/lower case BASIC keyword KBD. None of these keyboards contained a key ...


23

Of the variants produced in a relatively large series - let me remind you about the keyboard connection on the Commodore 128D - it was connected using a 25-pin interface, 23 lines of which directly represented the matrix of keys.


10

That would be USB, Audio out, Microphone in, FireWire. And PCMCIA slot above the two connectors. And there is a connector for a docking station at the bottom.


9

Then why did SCSI require so many pins? Differential signaling. The original standard was actually a 25-pin system using an 8-bit parallel signal going in one direction only. There was a separate parity pin, and lots of signal pins for things like device select and flow control. But in many respects it was similar to the DB-25 printer cable, just faster. ...


8

The Sinclair QL also had two RS232C ports which used an unusual combination of a ASIC (ZX8302) and Intel 8049 to provide two physical ports (with non standard connectors) but could not be used independently. The two ports were nominally for printer and modem use, but during development the built in modem of the QL was dropped, but the case retained the ...


8

Early micro/home computer used parallel keyboards. These were (usually) called 'ASCII' Keyboards. A good example is the Apple II, which implements a protocol almost exact like you imagined - sans interrupt that is. A key press was presented as 7 data bits with ASCII like encoding plus a flag at bit 7 indicating a key press, cleared whenever the port was read....


6

For a keyboard that includes a shift key to be useful, either the CPU must poll it often enough to observe the state of the shift key whenever another key is pushed, or the keyboard must capture enough information without CPU intervention to know whether a keystroke represents a shifted or unshifted character. In systems that use the former approach, there's ...


4

The LINC (Laboratory Instrument Computer), the first computer I programmed in 1965, had a one-key rollover. When a key was pressed on its Soroban Engineering keyboard, a solenoid locked that key down and all the other keys up, sending a signal to the computer. Whatever computer program was running could then take its time (sometimes a sizable fraction of a ...


4

The NES with its multitap accessory is a potential answer, if you'll accept some logic in the accessory. NES controllers use a 1-bit serial protocol. The host strobes to begin a transfer, causing the joypad to load its current state into a shift register, and the host then clocks in 8 bits, each representing one of the 8 inputs. It's actually the CPU that ...


4

A second bite of the cherry: amongst others, the WD177x family are popular floppy controllers that were used in or with a variety of 8-bit machines including the MSX, the Acorn Electron and later models of the BBC Micro, the Oric and the TRS-80. They are serial controllers because floppy drives provide a single data line, which the controller monitors for ...


3

In the Commodore 16/116/Plus-4, the Cassette connector and the serial (floppy and printer) port are both implemented via the CPU's single built-in I/O port which can be accessed by code at addresses $0000/$0001 (the same port that is used for the bank switching logic in the C64). Most lines of the two interfaces use separate bits of that one 8-bit port, but ...


3

The Sinclair ZX81 had a single Uncommitted Logic Array (ULA) chip that controlled both the screen and the cassette port. Consequently, accessing the cassette (loading or saving) would cause stripes to appear on the screen. It also controlled the keyboard, causing the screen to flicker at each keypress, but the keyboard was built-in and so it doesn't count ...


3

The Commodore 64 used a single CIA for both the keyboard and joystick (or paddles). This made reading both the keyboard and the joystick at the same time a bit of challenge, see this answer for details (complete with schematics). As for an explanation of "why", I guess the answer is always "to save parts and make it cheaper".


3

Not exactly a parallel interface, but the TRS-80 (models 1, 3 and 4) had a memory mapped keyboard! 8 address lines were matrixed to 8 data lines by the keys (and some diodes). The keyboard scan routine would start by looking at 0x38FF and if it got back 0x00 then no keys were pressed. If non-zero it would check 0x3801, 0x3802, 0x3804, up to 0x3880 and check ...


2

I assume these games were not completely recreated from scratch when they were ported to DOS. At least they could reuse the artwork and level files. Same way they were ported between different consoles. Reprogrammed while, as mentioned, saving as much resources (graphics, sounds, maps) to keep it the same game. After all, the PC is just another console with ...


2

The IBM 1130 used a keyboard mechanism from a keypunch. It constructed a 12 bit code for each key press mechanically, in parallel. The code was the sparse character code used on punched cards. The keyboard driver translated this to 8-bit EBCDIC. When computers were built from discrete transistors (or even vacuum tubes), serial interfaces were rare unless the ...


2

My first computer was a Big board by Fregusion. It ran CP/M and had a parallel keyboard as one of three console options (The others being a rs232 keyboard or a rs232 console). Since it was a kit It did not come with a keyboard (or power supply, crt, floppy drives, etc.) but expected ascii (or eight bit, one keyboard had a binary key which was wired to a 8x ...


1

I think the canonical example from the 16-bit era is the two ports on the Macintosh provided by a single Zilog 8530 and able to be used for serial, printer, modem, and AppleTalk networking based on user configuration. Of course this was influenced by the modem and printer port on the 8-bit Apple //c, but those ports relied on 2 independent 6551 UARTs. In ...


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