Singer 40 - Disc Drive Timing and Performance; Key Operational Timings

7 TIMING CONSIDERATIONS
Table 7-1 shows some of the more important operational timings for the
Models 40 and 42 Disc Drives.
Table 7 -1. Timings
Rotation Time
25.0 ms.
Arm Positioning Times
Minimum
2.5 ms.
Average 73.0 ms.
Maximum
135.0 ms.
Minimum arm positioning time is the amount of time required to move the read/
wri te head mechanism from one track to the next sequential track. A verage arm
positioning time is the amount of time required to move the read/write mecha-
nism from track 000 to track 099. Maximum arm positioning time is the amount
of time required to move the read/write head mechanism from tack 000 to
track 199.
Once the read/write head mechanism is positioned at the proper track, a read
operation takes 0.5 to 25.5 ms. These figures include the rotational delay time 1
(0 to 25 ms.) and the time needed to read a sector (0.5 ms.). If retries are
necessary, each retry takes 25 ms.
Once the read/write head mechanism is positioned at the proper track, a write
operation takes 26.5 to 51.5 ms. These figures include:
• the rotational delay time (0 to 25 ms.)
• the amount of time required for the Disc Controller to execute a special
timing algorithm (1 ms.)
• the amount of time required to write a sector (0.5 ms.)
• the amount of time required to rotate to the sector and then to read
the sector (25 ms.).
1 Rotational delay time is the amount of time needed for the desired sector to move to
the read/write heads.
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Models 40 to 42 Reference Manual
7-1