wok-next view runcom/description.txt @ rev 21545

updated cgames (2.2 -> 2.2b)
author Hans-G?nter Theisgen
date Sun Jun 21 17:35:44 2020 +0100 (2020-06-21)
parents f32d3ba00836
children
line source
1 Runcom support DOS `.com` binary files and boot sector files.
2
3 ### 1. The DOS `.com` support
4
5 Runcom provides few BIOS and DOS (int 21H) interrupt handlers. Many `.com`
6 files may not work. DOS `.exe` are also supported.
7
8 You can test it with the file `/usr/bin/debug.com`, with the command line:
9
10 $ debug.com
11
12 ### 2. The boot sector image support
13
14 A boot sector image is a 512 bytes file ending with the **0xAA** and **0x55**
15 bytes with the `.bin` extension.
16
17 BIOS disk (int 13H) are emulated (CHS or LBA) with an image file:
18
19 - hard disk are image ./hd0, ./hd1, ... for disk 0x80, 0x81...
20 - floppy disk are image ./fd0, ./fd1 ... or /dev/fd0, /dev/fd1 if not found.
21
22 You can test it with the file `/usr/bin/debug.bin`, with the command line:
23
24 $ debug.bin
25
26 ### 3. The 512 bytes boot sector debugger `/usr/bin/debug.bin`
27
28 Usage:
29
30 f DX:CX load one CHS sector to 0000:7C00
31 t trace one step
32 g <address> go to adrs
33 d <address> display 16 bytes, CR for next 16 bytes...
34 e <address> <words>... enter memory byte/word/dword
35 m <segment> self move
36 + <segment> default segment offset
37
38 `seqment` and `offset` are hexadecimal values in `0000..FFFF` range
39
40 `address` is linear hexadecimal value in `00000..FFFFF` range or
41 `seqment:offset` words are bytes in `00..FF` range or words in `0000..FFFF`
42 range or double words
43
44 `CX` and `DX` are used by `INT13H/AL=01` BIOS interrupt.
45
46 Example:
47
48 m 0FC0 move debugger to 0FC0:0000 0FC0:01FF
49 f 1 read floppy boot sector to 0000:7C00
50 f 80:1 read hard disk master boot sector to 0000:7C00
51 g 7C0E ...