AT&T 3B2 Off-Line Diagnostic Manual page 174

Version 3 Hardware System Board Diagnostics - - - - - - - - - - - - - - - - - - - - -
Test Numbers:
Function:
Procedure:
18 and 19
These tests check the ability of the Floppy Disk Controller to write to and read
from opposite sides of a floppy disk.
The test procedure is as follows:
1. Write side I, track 79, sector 1 with an increasing data pattern.
2. Write side 0, track 79, sector 1 with complement pattern.
3. Read side I, track 79, sector 1 and compare the data.
4. Read side 0, track 79, sector 1 and compare the data.
Hardware Tested: The WD1793 Floppy Disk Controller/Formatter is tested.
Data Returned: The failing test number (last number displayed on the system console before
failure) is returned.
Notes: None
3-134 OFF-LINE DIAGNOSTIC MANUAL