Previous: Creating a Release Disc under DOS
Up: Creating a Release Disc under DOS
Next: Operating System
Previous Page: Creating a Release Disc under DOS
Next Page: Operating System

Formatting

3.5'' inch discs, DOS version 3.3

At this writing, PC's compatible with PS/2's use either of two 3.5'' formats. One gives 720K, the other 1.4 megabytes. The Center uses only the 720K format, since the reliability of the higher density is not yet certain.

To format 3.5'' discs reliably, a drive preset to 720K is preferrable. Ideally it should be running under version 3.3, but as version 3.2 also runs 3.5'' discs, it may turn out to be on one of these. The Zenith Z286 is such a machine. The command should look like

FORMAT <drive-letter>: /S /N:9 /T:80

• The /S causes FORMAT to put a bootstrap on the disc, and put on the system files IBMBIO.COM and IBMDOS.COM. If /S is omitted, these files cannot be added later, because they are expected at reserved locations on the disc. However, if undesired versions, such as for DOS version 3.2, are placed on the disc, they can be removed, and the program SYS.COM, run under the desired system version, will (usually!) replace them with the correct versions.
• The /N:9 causes the drive to use 9 sectors per track.
• The /T:80 causes the drive to use 80 tracks. Together, they result in a 720K disc.

3.5'' inch discs, DOS version 5 or 6.2

The Center has not yet attempted to release (or create) discs under these versions.

5.25'' inch discs, DOS version 3.3 or 3.1

Note that DOS 3.1 doesn't contain the drivers needed for 3.5'' discs. Also, when the support library assumes the availability of particular DOS interrupt service routines, it should be confirmed that version 3.1 can supply them.

For formatting, the considerations listed for 3.5'' discs, above, apply. However, the FORMAT parameter /T must be changed to T:40, since 5.25'' discs only have 40 tracks, and therefore only 360K.

CAUTION: There is a wide variety of DOS machines made, with consequent variations in drive types and parameters, and in the subversions of DOS released with them. The steps listed here have had reasonable success on the Tandy 4000 (i386), the Zenith Z286, and the IBM PS/2 model 80, using mostly Dysan double-density double-sided discs. But in all cases when formatting booting discs, particularly for release, one must watch all steps carefully to see all is going correctly.

Best results are usually to be expected with disc media that match the settings needed. Discs rated for 720K are therefore probably preferable to those rated for 1.4 or 2.0 megabytes.