SCIENTIFIC MICRO SYSTEMS
OMTI 8150C, 8250, 8250C, 8157, 8257
Data bus: 16-bit, ISA
Size: Full-length, full-height card
Hard drives supported: OMTI 8150C/8250/8250C:Two MFM ST506/ST412 drives
OMTI 8157/8257:Two RLL ST506/ST412 drives
Floppy drives supported: OMTI 8150C/8157:None
OMTI 8250/8250C/8257:Two 360KB, 720KB, 1.2MB, 1.44MB
Sector interleave: 1:1
Maximum heads/cyl.: 16 heads and 2048 cylinders
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CABLE CONNECTIONS | |
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34-pin data cable connector-floppy drive (OMTI 8250/C/8257 only) |
J1 |
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20-pin data cable connector-drive 0 |
J3 |
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20-pin data cable connector-drive 1 |
J4 |
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34-pin control cable connector-hard drive |
J5 |
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4-pin connector-drive active LED |
J6 |
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Function |
Location |
Setting | |
| » |
Sysclk signal from AT bus input to 5098C chip |
W7 |
pins 1 & 2 closed |
|
No sysclk signal from bus, input tied low |
W7 |
pins 2 & 3 closed | |
| » |
Single speed floppy drives (OMTI 8250/8250C/8257 only) |
W8 |
pins 1 & 2 closed |
|
Dual speed floppy drives (OMTI 8250/8250C/8257 only) |
W8 |
pins 2 & 3 closed | |
| » |
Floppy precomp. values normal (8250/8250C/8257 only) |
W9 |
pins 2 & 3 closed |
|
Alt. floppy precomp. values (OMTI 8250/8250C/8257 only) |
W9 |
pins 1 & 2 closed | |
| » |
Factory configured - do not alter |
W10 |
N/A |
| » |
Hard drive port address is 1F0-1F7h |
W11 |
open |
|
Hard drive port address is 170-177h |
W11 |
closed | |
| » |
Floppy drive port address 3F0-3F7h (8250/8250C/8257 only) |
W12 |
pins 2 & 3 closed |
|
Floppy drive port address 370-377h (8250/8250C/8257 only) |
W12 |
pins 1 & 2 closed | |
| » |
Power-ground and chassis-ground separate |
W13 |
open |
|
Power-ground and chassis-ground connected |
W13 |
closed | |
