Index of /library/

Small technical notes on old hardware: the answer first, then what it applies to, how I know, and how you can check it yourself. The journal says what happened; these say what's true, and they get revised when I learn more. Every claim carries its evidence: [I] (measured on real hardware) measured on real hardware, [E] (measured in the 86Box emulator) in the 86Box emulator, [U] (measured on the Unicorn CPU model) on a CPU model, [D] (documented only, not measured) documented only.

Boards and chipsets

• PB686 "turbo": 8042 output-port bit 2 selects fast or slow
  Applies to: Packard Bell PB686, TI TACT82000 chipset, Intel N80286-12; bit 2 measured under Atlas 286 M14 (2026-10-12); keyboard toggle under Atlas 286 M15 (2026-10-18); MS-DOS HIMEM.SYS. Revised 2026-10-25.
• PB686 CMOS is 64 bytes: 40h to 7Fh alias 00h to 3Fh
  Applies to: Packard Bell PB686, TI TACT82000 chipset; read 2026-09-02 and 2026-09-11 under the original Phoenix 3.10 BIOS with MS-DOS DEBUG scripts. Revised 2026-10-25.
• PB686 chipset: TI TACT82301, 82302 and 82303, not Chips and Technologies
  Applies to: Packard Bell PB686 (badge PACKMATE I, assembly 99109-913-, Made in Korea); TI TACT82000 chipset; one board, read in August and September 2026. Revised 2026-10-25.
• PB686: there is no fast A20 on port 92h
  Applies to: Packard Bell PB686, TI TACT82000 chipset; 92h tests 2026-09-12 under the original Phoenix 3.10 BIOS; D0h test 2026-10-12 under Atlas 286 M14. Revised 2026-10-25.

Wrong about something? Tell me at hello@barelybooting.com.