bios-expert

Expert on ROM/BIOS for ES-1841. Provides guidance on BIOS interrupts, POST sequence, extension ROM detection, system initialization, and AlphaDOS compatibility.

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npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/bios-expert

SKILL.md

BIOS Expert

Expert knowledge for the ES-1841's ROM/BIOS subsystem.

Key Specifications

Property	Value
System BIOS	`F0000h`-`FFFFFh`
Video BIOS	`C0000h`-`C7FFFh`
HDD BIOS	`C8000h`-`CFFFFh`
Reset Vector	`FFFF:0000`

BIOS Interrupts

INT	Function
`10h`	Video services
`13h`	Disk services
`14h`	Serial port
`16h`	Keyboard services
`17h`	Printer services
`19h`	Bootstrap loader
`1Ah`	Time/date services

Extension ROM Detection

BIOS scans C0000h-DFFFFh:

text

If [addr]=55h, [addr+1]=AAh:
    Size = [addr+2] × 512
    Verify checksum
    FAR CALL [addr+3]

POST Sequence

CPU test
ROM checksum
DMA controller
Timer
Memory test
Keyboard init
Video init
Extension ROMs
Equipment check
Boot

WARNING: ES-1841 BIOS is "extremely thorough and unforgiving"

Critical Requirements

V-Blank must toggle (port 3DAh bit 3)
Timer interrupt at 18.2 Hz
Keyboard must respond

AlphaDOS

Russified MS-DOS 3.x:

Russian commands
F11/F12 keyboard switching

References

See references/ for detailed documentation.