Seagate ST02 SCSI Host Adapter

View of the 2 versions of the ST02.
  • J2: Internal SCSI Connector
  • J3(Early): Internal XT-type Floppy Connector
  • J5(Early), J3(Late) Internal AT-type Floppy Connector
  • J7(Early), J5(Late): Hard Drive LED Connector
  • J4: Aux Power Connector
    • Default settings are in Bold or are selected by a (Default) or (Optional)

    (JP1): BIOS Address
    16KB PROM (Early) 16KB PROM (Late)
    (A/B) (C/D) Address (1/2) (3/4) Address
    Off Off C800 Off Off C8000
    On Off (Invalid) On Off (Invalid)
    Off On CC00 Off On CC000
    On On DC00 On On DC000
    (Default is C800 or C8000.)

    (JP2): Zero Wait State (0WS)

  • (Default Setting): Open : Disabled.
  • (Optional Setting): Jumpered : Enabled.

    • (JP3): Interrupt Select
    (Early) (Late)
    (E/F)(1/2) (F/G)(2/3) Interrupt
    Off Off Disabled
    On Off IRQ#3
    Off On IRQ#5
    (Default is IRQs Disabled.)


    (JP5): Diskette Drive Type Selection (Early Version)

  • (Optional Setting): (M/N) Jumpered : 360KB/720KB type only.
  • (Default Setting): (N/O) Jumpered : 360KB/720KB & 1.2MB/1.44MB types.

    • JP6(Early) JP6(Late)

    (JP6): Hard Drive Register Emulation

  • (Default Setting): (Q/R) or (2/3) Jumpered : Disabled (1F2)
  • (Optional Setting): (P/Q) or (1/2) Jumpered : Enabled (1F4).

    • (JP7): Floppy Diskette Enable (Late Version)

  • (Default Setting): Open : Enable Floppy Support.
  • (Optional Setting): Jumpered: Disable Floppy Support.

    • (JP8): SCSI Bus Termination

  • (Default Setting): Jumpered : Enabled... Host Adapter supplies Term. Power.
  • (Optional Setting): Open: Disabled... Host Adapter does not supply Term. Power.

    • The ST02 uses a Future Domain SCSI Controller IC, but uses a BIOS modified by Seagate to support their SCSI drives. It's support was limited to a maximum of 2 drives until BIOS version 3.3, when additional support was added. The 3.3 version of the ST02 also allowed an external SCSI connector option. Seagate shipped a special formatter program with early adapters, and a Low Level Formatter utility is available through use of the DOS Debug command as follows:
    C:\debug <enter>
    -g=c800:5 <enter>

    ...where c800 is the address you set the Host Adapter at.
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