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Format of DR DOS 5.0-6.0 internal variable table

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Offset Size Description

00h

WORD

???

02h

WORD

segment of ???

04h

WORD

offset within DOS data segment of history control structure for COMMAND.COM history buffer (see #01586)

06h

WORD

offset within DOS data segment of history control structure for application history buffer (see #01586)

08h

BYTE

initial history state flags (see #01583)

09h

2 BYTEs

???

0Bh

WORD

KB of extended memory at startup

0Dh

BYTE

number of far jump entry points

0Eh

WORD

segment containing far jumps to DR DOS entry points (see #01587)

10h

WORD

(only if kernel loaded in HMA) offset in HMA of first free HMA memory block (see #01588) or 0000h if none; segment is FFFFh

12h

WORD

pointer to segment of environment variables set in CONFIG, or 0000h if already used

---DR DOS 6.0---

14h

WORD

(only if kernel loaded in HMA) offset in HMA of first used HMA memory block (see #01588) or 0000h if none; segment is FFFFh

16h

8 BYTEs

???

1Eh

WORD

offset in DOS data segment of full COUNTRY.SYS filename

20h

8 BYTEs

???

28h

WORD

offset in DOS data segment of SHARE hook table

2Ah

2 BYTEs

???

2Ch

WORD

offset in DOS data segment of far pointer to INT 2F/AX=1000h handler

Note:

The segment used for the DR DOS 6.0 CONFIG environment variables (excluding COMSPEC, VER and OS) is only useful for programs/drivers called from CONFIG.SYS. The word is set to zero later when the area is copied to the COMMAND.COM environment space. This allows CONFIG.SYS to pass information to AUTOEXEC.BAT.
The Novell DOS 7 KEYB uses offsets 10h,14h, and 2Ch in the same was as for DR DOS 6.0, so it is likely that the entire table is the same.