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

[Image]

                             CABLE CONNECTIONS

  34-pin data cable connector-floppy drive (OMTI                J1
  8250/C/8257 only)

  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          W7          pins 1 & 2
      5098C chip                                               closed

      No sysclk signal from bus, input            W7          pins 2 & 3
      tied low                                                 closed

  »   Single speed floppy drives (OMTI            W8          pins 1 & 2
      8250/8250C/8257 only)                                    closed

      Dual speed floppy drives (OMTI              W8          pins 2 & 3
      8250/8250C/8257 only)                                    closed

  »   Floppy precomp. values normal               W9          pins 2 & 3
      (8250/8250C/8257 only)                                   closed

      Alt. floppy precomp. values (OMTI           W9          pins 1 & 2
      8250/8250C/8257 only)                                    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         W12          pins 2 & 3
      (8250/8250C/8257 only)                                   closed

      Floppy drive port address 370-377h         W12          pins 1 & 2
      (8250/8250C/8257 only)                                   closed

  »   Power-ground and chassis-ground            W13            open
      separate

      Power-ground and chassis-ground            W13           closed
      connected