Micropolis hard Disk Drives, Specifications, Support, Specs, Jumpers, Manual, Images

Micropolis 1325

Hard Disk Drive


Model Capacity Size Height Interface Bus Type
Micropolis 1325 69MB 5.25" FHT ST506 MFM

micropolis 1325 picture micropolis 1325 picture
micropolis 1325 picture


Size 5-1/4 Inch
Interface ST-506/412
Interface Type 
Encoding Method MFM (Modified Frequency Modulation)
Formatted Capacity 71.3 MB
Disks 5
Heads 8
Cylinders 1024
Sectors 17
Buffer Size N/A
Average Seek 28 ms
Single Track 6 ms
Rotation Speed/Avg. Latency 3600 rpm +/- 0.5%
Transfer Rate to / from. media 5 Mbits/sec
Transfer Rate to / from buffer N/A
Tracks Per Inch (TPI)
Bits Per Inch (BPI)
Dimensions 8.0"L x 5.75"W x 3.25"H
Weight 5.75 lbs.

Power Requirements

+12V +/-5% +5V +/-5% Power
Spin up 3.9A (max)
Read / Write 2.0A avg 0.9A avg
Typical 32 Watts


Drive Addressing and Interface Termination

DS1, DS2, DS3, DS4 Drive Select Jumpers
  The Drive Select jumper locations are identified as DS1, DS2, DS3, and DS4. Only one Drive Select jumper is installed on a drive. The drives are shipped with the jumper installed at DS1. For every drive in a PC/AT installation, move the jumper from DS1 to DS2 (the special twisted interface cable that is generally used takes care of assigning a unique address to each drive). Some other systems may require that each drive be jumpered to a unique address (i.e., different DS numbers).

RN1 Interface Terminator
  The Interface Terminator factory installed at RN1 provides proper termination for the interface lines. When daisy-chaining multiple 1325 drives, leave the terminator in the last physical drive on the daisy chain cable; remove the terminator from each of the other drives. In most PC/AT installations, the C: drive is actually at the end of the cable and should retain the terminator.

W1 Write Fault Latch
  W1 is the Write Fault Latch. If W1 is present and the drive encounters a write fault, all writing to the drive is inhibited until after the drive has been de-selected. If W1 is absent, fault conditions are not latched. Drives are shipped with a jumper installed at W1; remove it for PC/AT installations.

W2 is always installed.

W7 is never installed.

W8 is always installed.

Digital Equipment Corporation (DEC) used the Micropolis 1325 drives white-labeled as the DEC RD53 hard-disk drives for their PDP11/10 VAX machines. To make a non-DEC Micropolis drive work with a DEC system, jumper R7.
DEC RD53-A and RD53-EA with skid plate.
DEC RD54 was a Maxtor drive.