82077AA Datasheet, PDF (47/62 Pages) Intel Corporation – CHMOS SINGLE-CHIP FLOPPY DISK CONTROLLER

82077AA
Figure 9-1 Standard IBM PC AT Floppy Disk Controller
290166 – 28
Table 9-1 indicates the drive and media types the
IBM PC AT disk controller can support This re-
quires the data separator to operate at three differ-
ent data rates 250 Kbps 300 Kbps and 500 Kbps
Clocks to the data separator and disk controller
need to be prescaled correspondingly to accommo-
date each of these data rates The clock prescaling
is controlled by the Data rate Select Register (DSR)
Supporting all three data rates can compromise the
performance of the phase lock loop (PLL) if steps
are not taken in the design to adjust the perform-
ance parameters of the PLL with the data rate
Table 9-1 Standard PC AT
Drives and Media Formats
Capacity
Drive
Speed
Data
Rate
Sectors Cylinders
360 Kbyte 300 RPM 250 Kbps 9
40
360 Kbyte 360 RPM 300 Kbps 9
40
1 2 Mbyte 360 RPM 500 Kbps 15
80
360 Kbyte diskette in a 1 2 Mbyte drive
47