Oct 1, 2018 · The "640k limit" (hole in contiguous RAM) was just 1 of a series of short-sighted, odd, and/or bad decisions involving the PC. Others include a) IBM choosing 8086 family over 68000. b) IBM not buying MSDOS outright instead of …

Oct 21, 2024 · The first hard drives appeared later on IBM 5160 PC/XT and the first drives were 10MB, with parameters of 306 cylinders, 4 heads, and 17 sectors per track. The XT hard drive adapter had a separate hard disk BIOS which hooked the INT 13H to provide hard disk as drive 80h and as a fallback for other drives called the motherboard BIOS for handling ...

Jan 21, 2018 · Hardware-wise the PC floppy controller also supports this. But as the original housing only allowed two (full height) drives, the controller thus split the interface onto two (proprietary) connectors: one PCB header for up to two internal drives, and a DB37 for two external drives (separate housing).

Jun 20, 2017 · Although the pinouts are not too bad. The IBM DIN and PS/2 sockets have pins as below: 1: Clock 2: Data 3: Reserved (in practice, usually a reset line) 4: Ground 5: +5V . I would suggest: Use a USB-RS232 adaptor and wire the DIN plug to a DB25 or DB9 RS232. The keyboard will then appear to the PC as being on a standard COM port.

IBM PC power supplies have output voltages of +5 V, −5 V, +12 V, and −12 V. Among these, −5 V and −12 V are not commonly used in modern systems. I am testing an old AT power supply with a multimeter, ...

Apr 19, 2018 · The IBM PC AT, which used it, was released in late 1984. Two and a half years is a long time to design a new computer that is a fairly modest upgrade on existing technology, and a long time for new technology as commercially important as the 286 to go unused.

Jul 11, 2018 · While the IBM PC marketing was a major feat pulled out by IBM+Microsoft, the IBM PC hardware together with the DOS OS was a throwback at least 1 decade in the past for 8-bits hardware, CP/M compatibility, and terrible sound and graphics capability that still haunts us to …

Jul 23, 2021 · And regarding the IBM PC specifically, it is likely that general specs were first fixed before actually it was designed. If the specs say that it must have serial connectivity up to 9600 bps, then that's the specs, even if designers later on …

Jun 8, 2020 · While this is still true today, it's even more relevant for back then, when a board like for an Apple II or IBM-PC wasn't layouted in five days, but took several weeks, if not month of intense work (*1). Having said that, there are also several practical reasons. Having chips nicely aligned eases layout, simplifies debugging and likewise patching.

Jan 19, 2024 · Ctrl-Alt-+/Ctrl-Alt-- support was a standard feature in both AMI and Award BIOSes at least around 1990-1996. On chipsets with software-controllable speed, the chipset support package for that BIOS included the necessary customizations to make speed switching wo