MS-DOS 6.22 Boot Menu Configuration File

In MS-DOS 6.22, system configuration choices and startup menu definitions are stored directly inside the CONFIG.SYS file located in the root directory of the boot drive. This article explains the role of CONFIG.SYS in managing the multi-configuration boot menu, how configuration blocks are structured, and how the user's menu choice is processed during the boot sequence.

The Role of CONFIG.SYS

The CONFIG.SYS file is a plain text file that DOS reads immediately after the operating system kernel (IO.SYS and MSDOS.SYS) loads into memory. Introduced to allow multiple startup configurations in MS-DOS 6.0 and refined through version 6.22, the multi-config feature allows users to define alternative system configurations—such as separate profiles for gaming, networking, or general productivity—all contained within this single file.

How the Boot Menu Is Structured

The boot menu is defined within CONFIG.SYS using specialized section headers:

  • [menu]: Declares the start of the boot menu options.
  • menuitem: Defines an selectable configuration block and its associated description text (for example, menuitem=GAME,MS-DOS Gaming Configuration).
  • menudefault: Specifies the default block to boot if the user does not make a selection within a specified timeout period.
  • menucolor: Sets the foreground and background text colors for the menu interface.

Below the [menu] block, individual configuration sections are declared using bracketed block names (e.g., [GAME], [NORMAL]). Each block contains the specific drivers, memory managers (such as HIMEM.SYS and EMM386.EXE), and system parameters (BUFFERS, FILES, DOS=HIGH,UMB) assigned to that profile. A [common] block can also be included for directives that apply to every choice.

Runtime Selection Handling

When you select an option from the menu during boot:

  1. MS-DOS reads CONFIG.SYS and executes only the directives within the matching configuration block, alongside any [common] blocks.
  2. MS-DOS assigns the name of the chosen block to a temporary internal environment variable named %CONFIG%.
  3. After CONFIG.SYS completes, AUTOEXEC.BAT executes. Batch scripts inside AUTOEXEC.BAT use the %CONFIG% variable alongside GOTO statements (for example, GOTO %CONFIG%) to load matching software, sound card drivers, mouse drivers, or network settings corresponding to the selection made in CONFIG.SYS.