
SCIENTIFIC MICRO SYSTEMS, INC.

OMTI 7250

  Data bus:                   50-pin SCSI interface

  Size:                       5.75" x 8"

  Hard drive supported:       Up to two ST506/412 MFM drives, up to two
                              ST506/412 RLL 2,7 drives, up to two ESDI
                              drives

  Floppy drives supported:    Two 360KB, 720KB, 1.2MB, 1.44MB drives or
                              8"



[Image]

                           CONNECTIONS

                  Function                        Location

  50-pin SCSI interface                              J1

  34-pin ESDI or MFM disk control connector          J2

  20-pin data cable connector                        J3

  20-pin data cable connector                        J4

  34-pin floppy drive connector                      J7

  DC power connector                                 J10

                               SCSI ADDRESS

     SCSI ID              W1                 W2                 W3

          0             open               open               open

          1            closed              open               open

          2             open              closed              open

          3            closed             closed              open

          4             open               open              closed

          5            closed              open              closed

          6             open              closed             close

          7            closed             closed             closed

                        USER CONFIGURABLE SETTINGS

               Function                    Location           Setting

     SCSI parity enabled                     W4               closed

     SCSI parity disabled                    W4                open

     Factory configured - do not             W5                open
      alter

     ST506/412 interface for drive           W6                open
      select 1 enabled

     ESDI interface for drive                W6               closed
      select 1 enabled

     ST506/412 interface for drive           W7                open
      select 2 enabled

     ESDI interface for drive                W7               closed
      select 2 enabled

     TRMPWR supplied by board          W14/pins 1 & 2         closed

     TRMPWR supplied by SCSI bus       W14/pins 2 & 3         closed

     Ready signal from pin 2 to FDC          W15               open
      765 disabled

     Ready signal from pin 2 to FDC          W15              closed
      765 enabled

     Ready signal from pin 34 to             W16               open
      FDC 765 disabled

     Ready signal from pin 34 to             W16              closed
      FDC 765 enabled

     Ready override to FDC 765               W17               open
      disabled (Rev. B only)

     Ready override to FDC 765               W17              closed
      enabled (Rev. B only)

     Motor On signal delay enabled           W18               open

     Motor On signal enabled                 W18              closed

     Factory configured - do not             W37               open
      alter

     Factory configured - do not             W38               open
      alter

     Factory configured - do not             W39               open
      alter

       Note: Drive select 1 & 2 refer to the drive select jumper setting
       on the drive itself and should be set to 1 & 2 respectively.

       The location of W39 is unidentified.

                       LUN 0 DISK TYPE CONFIGURATION

             Drive Type                      W9                 W10

     ST506/412                             open               open

     ESDI                                 closed              open

     Removable ST506/412                   open              closed

     Flexible disk                        closed             closed

                       LUN 1 DISK TYPE CONFIGURATION

             Drive Type                      W12                W13

     ST506/412                             open               open

     ESDI                                 closed              open

     Removable ST506/412                   open              closed

     Flexible disk                        closed             closed

                      LUN 0/1 FLEXIBLE DISK DATA RATE

            Data Rate                  W8(Lun 0)           W11(Lun 1)

     250 Kbit                           open                 open

     500 Kbit                          closed               closed

  Note: These settings apply only when W9 & W10 are both closed.

                     LUN 0/1 SECTOR TYPE CONFIGURATION

               Mode                     W8(Lun 0)          W11(Lun 1)

     Soft sector enabled                  open               open

     Hard sector enabled                 closed             closed

  Note: These settings apply only when drive type is set to ST506/412.

