SELECT
was introduced in IBM PC DOS 3.0, along with internationalisation support, and made available in MS-DOS starting with version 3.3.
Its purpose is to create a bootable disk with support for a given country code and keyboard layout. The syntax, starting with version 3.2, is
SELECT [[drive1:] drive2:[path]] country keyboard
where drive1
is the source drive (A
by default), drive2
the destination drive (B
by default), country
is one of the supported country codes (033 for France, 049 for Germany — West Germany at the time — etc.), and keyboard
is one of the available keyboards (FR
, GR
etc.).
This was effectively the installation procedure for floppy-based versions of DOS, outside the US: prepare a blank floppy, boot with DOS disk 1, and run SELECT
with the appropriate country and keyboard code. This would result in a usable DOS disk, with all the contents of DOS disk 1, and a correctly-configured keyboard as soon as the system was booted.

Version 3.0 and 3.1 of SELECT
use DISKCOPY
to copy the source disk to the destination disk, formatting the latter if necessary. Version 3.2 and 3.3 use FORMAT
and XCOPY
instead; version 3.3 supports hard drives (although running FDISK
is left as an exercise for the user, before running SELECT
). In both cases, the destination disk is erased, and all the contents of the source disk are copied, not only the files required to support the desired country and keyboard. In version 3.2, if the source disk doesn’t include the KEYBxx
file required for the desired keyboard, the user is prompted to instead the disk containing it. All versions then write an appropriate CONFIG.SYS
and AUTOEXEC.BAT
to the target disk, containing respectively
COUNTRY=<country>
(adding the COUNTRY.SYS
path too if necessary), and
PATH ...
KEYB...
ECHO OFF
DATE
TIME
VER
The default path (PATH
above) depends on the installation path (the second parameter).
In version 4.0 of PC DOS and MS-DOS, SELECT
became an interactive installation tool, which was started automatically from the installation disk (or the “Select” disk on 5.25” disk sets).
In version 5.0 of PC DOS and MS-DOS, the setup program was renamed to SETUP.EXE
and introduced support for upgrading DOS. This is where DELOLDOS
comes from: when upgrading, SETUP
would create DELOLDOS
, which could be used to undo the upgrade, restoring the previous version of DOS (and its boot sector etc.).
There appears to have been another version of SELECT
, written by Karl D. Wright for Phoenix Technologies, and included in at least some OEM versions of MS-DOS 3.2; a quick look through it suggests it does the same thing as the “official” SELECT
.
According to The MS-DOS Encyclopedia, SELECT
was available in PC DOS 2.0, but my PC DOS 2 disks don’t have it and there wouldn’t have been much use for it on PC DOS 2 which didn’t have either the COUNTRY
statement or the KEYBxx
commands.
SELECT
command that some may have enjoyed with 4DOS, of course. (-: