China DOS Union

After downloading Wengier's ROM-DOS 7.1 system disk, I compared it with the MSDOS 7.1 system disk I made.

First is the memory usage at startup (below). The tool used was MI from PCTOOLS9. Obviously, in terms of memory usage, MS-DOS has a slight advantage. If we consider loading the same number of programs, ROM-DOS uses about 32K more conventional memory than MSDOS.

I. Memory usage after booting Wengier's ROM-DOS boot disk
Memory Info V9 ?(c)1993 Central Point Software, Inc.

Addr. Total bytes Program or device driver
----- ----------- --------------------------
0463h 3,824 Device=HIMEM Attr=8000h Name=XMSXXXX0
0553h 5,008 Device=VIDE-CDD Attr=C800h Name=CDROM1
0BD5h 14,096 Device= Attr=065Eh Units: 15
0F58h 4,960 COMMAND /p /e:640
10E5h 384 KILLER
10FEh 3,920 DOSKEY
11F4h 32,368 MSCDEX /D:CDROM1 /K
19DCh 3,312 CTMOUSE
1AACh 672 XMSDSK
1AD7h 1,504 ESCAPE
1B36h 543,904

655,360 bytes (640k) total DOS 7.10 conventional memory.
543,904 bytes (531k) largest executable program.

0 bytes Extended (AT/286/386) memory, reported by BIOS.
64,384k bytes XMS 2.0 (4.00) memory: 1,024k used + 63,360k free. DOS in HMA.

===================================================================================

II. Memory usage after booting my WIN98SE DOS (MSDOS7.1) tool disk
Memory Info V9 ?(c)1993 Central Point Software, Inc.

Addr. Total bytes Program or device driver
----- ----------- --------------------------
0213h 3,824 Device=HIMEM Attr=8000h Name=XMSXXXX0
0303h 4,992 Device=VIDE_CDD Attr=C800h Name=MSCD001
043Ch 1,440 Device=RAMDRIVE Attr=4800h Drive F
0497h 544 IFS=
04BAh 752 IFS=桤
0689h 7,168 COMMAND
0861h 5,728 DOSKEY
09C8h 7,072 MOUSE
0B85h 13,712 MSCDEX /D:mscd001 /L:G
0EDFh 594,448

655,360 bytes (640k) total DOS 7.10 conventional memory.
594,448 bytes (581k) largest executable program.

0 bytes Extended (AT/286/386) memory, reported by BIOS.
64,384k bytes XMS 2.0 (4.00) memory: 2,048k used + 62,336k free. DOS in HMA.

A few brief notes:
1、My MS-DOS 7.1 system disk also uses ROM-DOS's himem.sys;
2、The version of Vide_cdd.sys I use is a bit older, and uses a bit less memory
3、The MOUSE driver I use is from UCDOS, not CTMOUSE, because CTMOUSE conflicts with the Sanming network copy tool NC2002 on my disk, causing the latter's screen to become garbled, so I don't use it.
4、mscdex is not from MSDOS, but was renamed from FREEDOS's SHCDEX.EXE
5、The RAM disk created by the ROMDOS disk is 1M, while the RAM disk on the MSDOS disk is 2M.

However, ROMDOS is better in terms of disk capacity. The 4 core files of ROMDOS take up about 192K in total, while the 4 core files of MSDOS take up more than 380K; even without compressed drive support they still take 320K. The ROMDOS system floppy has about 110K more space to store more tools.

I want to clarify three points:

1: I did not do much optimization of the memory configuration for the ROM-DOS boot disk. For example, right now I am using MS's MSCDEX, which takes about 30K of memory. If I switched to my favorite CLOAKING+MSCDEX, then it would only take 4K of memory.

2: To enable UMB in ROM-DOS, you need ROM-DOS's dedicated UMB driver program (the EMM386.EXE or UMBLINK.SYS that comes with ROM-DOS), but I don't have it, because you have to buy it to get it.

3: ROM-DOS has three core files in total, not 4, namely IBMBIO.COM, IBMDOS.COM and COMMAND.COM, about 120K total, not 192K. And ROM-DOS.SYS is only useful when transferring the system with SYS.

Also, some files on the current ROM-DOS boot disk, such as COMMAND.HLP, MINICOM.COM, ROM-DOS.SYS, etc., can all be deleted.

The current COMMAND.HLP in it is from ROM-DOS version 6.22, and is not compatible with version 7.1, so it is completely useless and can be safely deleted; once you have COMMAND.COM, you don't need MINICOM.COM, so that can also be safely deleted; ROM-DOS.SYS is actually all the contents of the IBMBIO.COM file starting from the third line, used only by the SYS command, and is normally useless. It can also be rebuilt at will from the IBMBIO.COM file, so it can be deleted too. I put the above files on the boot disk only to keep some downloaded ROM-DOS files, not because ROM-DOS actually needs them.

Can the ROM-DOS boot disk also be used under MS-DOS (6.22)?
And how can the SYS command rebuild it from the IBMBIO.COM file?
I'd also like to ask the experts for some guidance.

Of course ROM-DOS cannot be used under MS-DOS; rather, it is an independent DOS operating system that is compatible with MS-DOS 7.1.