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WD.DOC
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1987-01-06
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WD1002S-WX2 Hard Drive Controller
The following information on the Western Digital Controller is for
the WD1002S-WX2 taken from the Western Digital Installation Guide.
If you need help doing a low-level format on the drive, please
leave a message in the Hard Drive Conference, Sparta PCBoard
(201) 729-7056.
The BIOS ROM is used to define individual disk drive parameters.
Currently there are two varieties of BIOS ROMs available. The
standard BIOS ROM contains a selection of four sets of drive
parameters that can be used with most existing disk drives.
In addition to this same selection of parameters, another BIOS
ROM, called Auto Config BIOS ROM, allows manual assignment and
modification of these drive parameters; has the ability to load
a drive defect list; and lets the user logically format one disk
drive as two virtual drives.
Both versions of the BIOS ROM contain four drive configuration
tables or BIOS tables as listed below:
BIOS Drive Tables contained within the following BIOS ROMS
Standard - WD62-000042-013
Auto Config - WD62-000043-010
Table 0
Specifications Drive Types
Drive Capacity 20MB Microscience HH725/HH325
Cylinders 612 Tandon TM262/362
Heads 4
RWC 613(none)
WPC 613(none)
Step Rate Option 5
Table 1
Drive Capacity 10MB Miniscribe 3012/3212
Cylinders 612
Heads 4
RWC 128
WPC 128
Step Rate Option 5
Table 2
Drive Capacity 20MB CDC 9415-525AT/9415-528
Cylinders 612 Miniscribe 3425
Heads 4 Mivil M125/M225/M325
RWC 613(none) Seagate ST225
WPC 128
Step Rate Option 5
Table 3
Drive Capacity 10MB Fujitsu m2233
Cylinders 306 LaPine 3065/3512/3522
Heads 4 Microscience HH612/HH312
RWC 306(none) Miniscribe 2012
WPC 0 (all) Rodime 252/352
Step Rate Option 5 Seagate ST412
SW1 Jumper Positions 1 - 4
BIOS Table Drive 1 Drive 0
SW 1-1 SW 1-2 SW 1-3 SW 1-4
0 Close Close Close Close
1 Open Close Open Close
2 Close Open Close Open
3* Open Open Open Open
*Shipping Configuration
SW1 Jumper Positions 5 - 8
SW 1-8 Open Reserved for BIOS ROM
SW 1-7 Open Reserved for BIOS ROM
SW 1-6 Open Reserved for BIOS ROM
SW 1-5 Open Reserved for BIOS ROM
The following jumpers cover the W1 - W7 jumper positions
Jumper Pin Connects Status
W1 2-1 Normal*
2-3 Factory Test Only
W2 2-1 Normal*
2-3 Factory Test Only
W3 Closed BIOS ROM Enabled*
Open BIOS ROM Disabled
W4 2-3 Device Address 320H*
2-1 Device Address 324H
W5 2-1 BIOS ROM Size 32K or 64K**
2-3 BIOS ROM Size 16K
W6 2-3 Reduced Write Current (8 heads)*
2-1 Head Select 3 (16 heads)
W7 2-1 INTRQ to INTRQ 5 on host connector**
2-3 INTRQ to INTRQ 2 on host connector
* - As Shipped - Jumper is installed
** - As Shipped - Jumper is installed, Pins 1 and 2 are joined via an
etch on the PCB. To change, the etch must be carefully
cut and a jumper installed.
Step Rates
The WD1015 Control Processor uses the CCB Option Byte to establish
the actuator step rate. This step rate is defaulted to either 70 or
75 microseconds on the installed version of the Control Processor. It
can be modified by the Auto-Config BIOS ROM. The control processor
is the chip located at U11 on the circuit board.
An older version of the control processor, P/N WD1015-14, supports a
maximum of 8 heads and is completely suitable for the lower capacity
ST506 type disk drives. The default step rate is 70 microseconds.
Today's control processor, the WD1015-24, supports up to 16 heads. It
includes controller support to the DMA and Syquest removable drives.
Other differences include: it no longer performs the unnecessary
controller self-test after power-on or soft resets; the processor allows
faster step rates; and the default step rate is 75 microseconds.
The Auto-Config BIOS ROM can be used to change the step rate of either
the WD1015-14 or -24 control processors. Table 5 lists the available
step rates for both the WD1015-14 and the WD1015-24. Overall system
performance will be enhanced by selecting the fastest possible step rate
supported by the attached drive.
Table 5
WD1015-14 Step Rates
DEC BIN Step Rate Comments
0 000 3 ms
1 001 3 ms
2 010 3 ms
3 011 3 ms
4 100 200 us
5* 101 70 us Standard Buffered Seek Rate
6 110 3 ms
7 111 3 ms
WD1015-24 Step Rates
0 000 3 ms
1 001 45 us
2 010 60 us
3 011 18 us
4 100 210 us
5* 101 75 us Standard Buffered Seek Rate
6 110 30 us
7 111 18 us
* Default value in WD BIOS ROMS