config.sys

[MrMatt2532]

what does stacks=o,o and dos=high,umb do in the config.sys file?

[reghakr]

It pertains mainly to older version of DOS. If you're running Win98, those settings are handled automatically.

In Internet Explorer, go to Help>Online Support, choose the Microsoft Knowledge Base, then check the box that says specify an article ID number, then paste Q84300 into the search box. I'ts titled "How to Use the STACKS= Setting in the CONFIG.SYS File"

Here's what I've located on dos=high,UMB:

DOS=HIGH Asks MS-DOS to Run in the HMA
If DOS=LOW or no DOS= command is in the CONFIG.SYS file, MS-DOS and its data are initialized and loaded into their final place in low memory before the DEVICE= and DEVICEHIGH= commands are processed.

If the DOS=HIGH command is in the CONFIG.SYS file, MS-DOS data (which must remain low for compatibility) is loaded into its final place in conventional memory. After each device driver is initialized, a check is made to determine if an XMS driver has been installed. If so, and if the HMA is available, MS-DOS is moved into the HMA. If not, MS-DOS keeps checking after each DEVICE[HIGH]= command, and then begins processing the INSTALL= commands.

If a DOS=HIGH command exists but MS-DOS hasn't loaded high (if no XMS driver was loaded or the HMA wasn't available), MS-DOS reports "HMA not available/loading DOS low" and loads itself into conventional memory above all the installable device drivers and/or terminate-and-stay-resident (TSR) programs loaded with INSTALL=.

The transient portion of COMMAND.COM remains in conventional memory whether MS-DOS is loaded high or low. Most of the COMMAND.COM resident portion, any software code pages, and the disk buffers (usually) also load high if DOS=HIGH is in the CONFIG.SYS file.

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

DOS=UMB Asks MS-DOS to Manage UMBs
The DOS=UMB command asks MS-DOS to allocate any UMBs available through the XMS to itself. MS-DOS then makes UMBs available through its own memory- management services in Interrupt 21h, including:
Function Description Version
-------------------------------------------------------
48h Allocate memory 2.0
49h Free allocated memory 2.0
4Ah Set memory block size 2.0
5800h Get allocation strategy 2.0
5801h Set allocation strategy 2.0
5802h Get upper-memory link status 5.0
5803h Set upper-memory link status 5.0
If DOS=UMB is in the CONFIG.SYS file, EMM386.EXE reports that 0 (zero) UMBs are available from the MS-DOS command prompt, and any program that attempts to use UMBs through the XMS services is unable to find them.

Users can determine whether MS-DOS has any UMBs available by using the MEM /C command. Programs can use Interrupt 21h, Function 5803h to determine if UMBs exist.

reghakr