I have a generic boot disk that I use on all of my retro PCs. I just noticed that on my Pentium 166 I barely had any conventional memory when using the disk vs the 619kB I have when shutting down to MS-DOS mode in Windows 98. I tracked down the issue to DBLSPACE, it's loading 81KB into conventional memory. The problem is I'm not loading DBLSPACE in the Config.sys or Msdos.sys or anywhere else that I know of. On my PIII 500 and P4 2.4 DBLSPACE doesn't load at all and I have plenty of conventional memory.

Autoexec.bat

1@ECHO OFF
2PROMPT=$P$G
3SET PATH=A:\WINDOWS;A:\WINDOWS\COMMAND;A:\CTMOUSE;A:\UNISOUND
4SET TEMP=A:\TEMP
5SET BLASTER=A220 I5 D1 H5 T4
6LH A:\WINDOWS\COMMAND\MSCDEX.EXE /D:MSCD001 /E
7REM A:\SHSUCDX\SHSUCDX.COM /D:MSCD001
8LH A:\CTMOUSE\CTMOUSE.EXE
9A:\UNISOUND\UNISOUND /V85 /VW85 /VF85 /VL00 /VC85 /VM00

Config.sys

1DEVICE=A:\WINDOWS\HIMEM.SYS
2DEVICEHIGH=A:\WINDOWS\EMM386.EXE RAM I=B000-B7FF
3DOS=HIGH,UMB
4DEVICEHIGH=A:\CDROM\VIDE-CDD.SYS /D:MSCD001
5REM BREAK=ON
6REM FILES=30
7REM BUFFERS=20,0
8REM STACKS=0,0
9REM LASTDRIVE=Z

Normally on Windows 98 I disable DBLSPACE in MSDOS.SYS, but the MSDOS.SYS on the boot disk only contains ";FORMAT" and nothing else.

Doing a step-by-step confirmation I see that DBLSPACE is loading before CONFIG.SYS is loaded.