追記
https://web.archive.org/web/20200328183820/https://sites.google.com/site/pcdosretro/ で、以下の資料はまだ入手可能です。
IBM PC BIOS source code reconstruction
Information
IBM PC BIOS version history
IBM PC BIOS - all 3 versions (dated 04/24/81, 10/19/81, 10/27/82)
IBM PC XT BIOS version 1 (dated 11/08/82)
IBM PC XT BIOS version 2 (dated 01/10/86)
IBM PC XT BIOS version 3 (dated 05/09/86)
IBM PC AT BIOS version 1 (dated 01/10/84)
IBM PC AT BIOS version 2 (dated 06/10/85)
IBM PC AT BIOS version 3 (dated 11/15/85)
IBM PC XT 286 BIOS (dated 04/21/86)
Related specs and information
BIOS functions
BIOS data area
Keyboard scan code/character code combinations
List of PC interrupts
80x86 instruction reference
Official Expanded Memory Specification (EMS) documentation: version 3.2 - version 4.0
Official eXtended Memory Specification (XMS) documentation: version 2.0 - version 3.0
Official Virtual Control Program Interface (VCPI) documentation: version 1.0
Official Virtual DMA Services (VDS) documentation: version 1.0
Official DOS Protected Mode Interface (DPMI) documentation: version 0.9 - version 1.0
VESA BIOS Extension (VBE) documentation: version 1.2 - version 2.0 - version 3.0
Master Boot Record (MBR) information and code disassembly
Microsoft FAT (File Allocation Table) file system documentation
Microsoft CD-ROM Extensions (MSCDEX) documentation
Relocatable Object Module Format (OMF) documentation
Microsoft Macro Assembler (MASM) version history
Microsoft C compiler version history
EMSやXMSのスペシフィケーションの資料がなくて、どうやってVzと付き合う
のでしょう?
いろいろ怖いです。自分が、、、、怖いです。
http://web.archive.org/web/20080216121237/http://ourworld.compuserve.com/homepages/r_harvey/doc_book.htm 英語で嫌かもしれませんが、こういう資料もあります。