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OMTI 8150C, 8250, 8250C, 8157, 8257

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

CABLE CONNECTIONS

34-pin data cable connector-floppy drive (OMTI 8250/C/8257 only)

J1

20-pin data cable connector-drive 0

J3

20-pin data cable connector-drive 1

J4

34-pin control cable connector-hard drive

J5

4-pin connector-drive active LED

J6

USER CONFIGURABLE SETTINGS

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