MacintoshでMS-DOSのdebugコマンドの動作確認をするのにどうしたらいいか悩んでいた。
windowsでも64bitだとdebugコマンドをどう動かしたらいいか、よくわからなかった。16bitモードらしい。
ネットで検索すると
FreeDOSもLinuxも動く、JavaScriptで作られた x86エミュレータがスゴイ件
https://www.softantenna.com/wp/software/x86-emulator/
virtual X86
http://copy.sh/v86/
ReactOS(32MB) - Restored from snapshot
Windows95(6.7MB) - Restored from snapshot
FreeBSD 10.2(13.0MB) - Restored from snapshot
Oberon(16.0Mb) - Native Oberon 2.3.6 (via)
Windows 98(12.0MB) - Including Minesweeper and audio, additional sectors are loaded as needed
Arch Linux (10.1MB) - A complete Arch Linux restored from a snapshot, additional files are loaded as needed
KolibriOS(1.4MB) - Graphical OS, takes about 60 seconds to boot
Linux 2.6(5.4MB) - With busybox, Lua interpreter and test cases, takes about 20 seconds to boot
Linux 3.18(8.3MB) - With internet access, telnet, ping, wget and links. Takes about 60 seconds to boot. Run udhcpc for networking. Exchange files through /mnt/.
Windows 1.01(1.4MB) - Takes 1 second to boot
MS-DOS 6.22(3.4MB) - Takes 10 seconds to boot. With Enhanced Tools, QBasic and everything from the FreeDOS image
FreeDOS(0.7MB) - With nasm, vim, debug.com, some games and demos, takes 1 second to boot
OpenBSD(1.4MB) - Random boot floppy, takes about 60 seconds
olar OS(1.4MB) - Simple graphical OS
Bootchess(0.2MB) - A tiny chess program written in the boot sector
MS-DOSのライセンスがどうなっているか調べてなかったので、Freedosを押して見た。
SeaBIOS (version rel-1.10.0-39-g3fdabae-dirty-20170530_144256-nyu)
Booting from Floppy...
FreeDOS kernel - SVN (build 2040 OEM:0xfd) [compiled Apr 7 2012]
Kernel compatibility 7.10 - WATCOMC - FAT32 support
(C) Copyright 1995-2011 Pasquale J. Villani and The FreeDOS Project.
All Rights Reserved. This is free software and comes with ABSOLUTELY NO
WARRANTY; you can redistribute it and/or modify it under the terms of the
GNU General Public License as published by the Free Software Foundation;
either version 2, or (at your option) any later version.
- InitDiskno hard disks detected
Can't disable A20 - ignored
FreeDOS HIMEM 2.07 [Feb 13 2003] (c) 1995, Till Gerken 2001-2003 tom ehlert
Interface : XMS 2.00 80386 64MB
Kernel: allocated 46 Diskbuffers = 24472 Bytes in HMA
FreeCom version 0.82 pl 3 XMS_Swap [Dec 10 2003 06:49:21]
Welcome to FreeDOS (http://www.freedos.org)!
Running on copy.sh/v86/
Try 'invaders' or 'snake' or 'tetris' for fun.
A:\>
debugコマンド起動。D(dump)
A:\>debug
-d
099F:0100 75 02 EB F2 FF 76 0C E8-70 81 59 8B 1E A8 00 89 u....v..p.Y.....
099F:0110 47 08 0B C0 74 12 FF 76-04 E8 5E 81 59 8B 1E A8 G...t..v..^.Y...
099F:0120 00 89 47 0A 0B C0 75 05-E8 C7 49 EB 0D 8D 86 F0 ..G...u...I.....
099F:0130 FE 50 E8 82 B7 59 0B C0-75 05 E8 32 B8 EB B7 8B .P...Y..u..2....
099F:0140 1E A8 00 C7 47 1A 01 00-33 C0 8B E5 5D C3 55 8B ....G...3...].U.
099F:0150 EC 83 EC 0A 8D 46 F6 50-8D 46 FA 50 8D 46 F8 50 .....F.P.F.P.F.P
099F:0160 8D 46 04 50 8D 46 FC 50-8D 46 FE 50 FF 76 04 E8 .F.P.F.P.F.P.v..
099F:0170 E0 FD 83 C4 0E 48 8B D8-83 FB 04 77 23 D1 E3 2E .....H.....w#...
u(dis assemble)
-u
099F:0100 7502 JNZ 0104
099F:0102 EBF2 JMP 00F6
099F:0104 FF760C PUSH WORD PTR [BP+0C]
099F:0107 E87081 CALL 827A
099F:010A 59 POP CX
099F:010B 8B1EA800 MOV BX,[00A8]
099F:010F 894708 MOV [BX+08],AX
099F:0112 0BC0 OR AX,AX
099F:0114 7412 JZ 0128
099F:0116 FF7604 PUSH WORD PTR [BP+04]
099F:0119 E85E81 CALL 827A
099F:011C 59 POP CX
099F:011D 8B1EA800 MOV BX,[00A8]
おお、動く。
#算譜(source)
copy/v86
https://github.com/copy/v86
"use strict";
/** @const */
var CPU_LOG_VERBOSE = false;
// Resources:
で始まっている。続いて次の３つのURLを示している。
https://pdos.csail.mit.edu/6.828/2006/readings/i386/toc.htm
https://www-ssl.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html
http://ref.x86asm.net/geek32.html
参考資料(reference)
FreeDOS
http://www.freedos.org
debugコマンド(MS DOS)
https://qiita.com/kaizen_nagoya/items/31542d281d16d135df66
文書履歴(document history)
ver. 0.10 初稿 20180714
ver. 0.11 参考資料追記 20180716
ver. 0.12 ありがとう追記 20230413
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