Sperry AT Doesn't Format High-Density Disks (74822)
The information in this article applies to:
• Microsoft MS-DOS operating system 5.0
• Microsoft MS-DOS operating system 5.0a
• Microsoft MS-DOS operating system 6.0
• Microsoft MS-DOS operating system 6.2
• Microsoft MS-DOS operating system 6.21
• Microsoft MS-DOS operating system 6.22
This article was previously published under Q74822
After you install MS-DOS on a Sperry AT, your machine may be unable to
format high-density (1.2-megabyte) disks. The disks may appear to format
correctly, but they do not write correctly (you receive "Sector not found"
errors if you try to use them).
Ensure the CMOS is set correctly, and possibly try using DRIVPARM or
DRIVER.SYS, but if your ROM BIOS is earlier than 1.58, you need to upgrade
To get the latest ROM versions, contact Unisys at (800) 448-1424 and select
option 4. Unisys will ask you for the BIOS "feature" appropriate to the
Look on the back of the machine by the serial number for a TYPE CODE.
The following applies, providing you have version 1.58 (the latest) AT
If the code is The BIOS "style" is
PC-IT type 3126-00 F4964-00
Micro-IT type 3137-00 A5222-00
The Sperry product included here is manufactured by Unisys, a vendor
independent of Microsoft; we make no warranty, implied or otherwise,
regarding this product's performance or reliability.
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