16 Bit SCSI Host Adapter  (250-4161)   BIOS             Faxback Doc. # 5087

BIOS Version 2.0C:

This was the first production BIOS for this board; it appeared on the 250-4161
board.  This BIOS treats SCSI hard drives as though they have 16 heads.  In
MS-DOS 3.30.00 operation, this BIOS can access all of the space on the SCSI
hard drives with a capacity less than 256 Meg; it cannot access all of the
space on SCSI hard drives with a capacity greater than 256 MEG.

If any program using the virtual mode of the 80386, or the programs which
involve direct hard drive to video transfers, are to be run in the MS-DOS
environment using this versin of the BIOS, the virtual device driver
700-4161 SCSIHA.SYS must be used in the CONFIG.SYS file and installed on the
system boot.  Programs which operate in this mode are Windows/386.
Desqview/386, MOD386, and others.

When a SCSI tape drive is used, a device driver called SCSITAPE.SYS must be
installed in the CONFIG.SYS file if the drive is to be used in the MS-DOS
environment.  This file is also on the 700-4161 diskette.

BIOS Version 4.03S:

This BIOS also treats SCSI hard drives as thought they have 16 heads.  This
BIOS appeared on the 250-4161A board as shipped.  In MS-DOS 3.30.00
operation, this BIOS can access all of the space on a SCSI hard drive with a
capacity less that 256 MEG; it cannot access all of the space on SCSI hard
drives with a capacity greater than 256 MEG.

On 80386-based MS-DOS3.30.00 systems, the 700-4161 SCSIHA.SYS driver need no
longer be used with virtual mode programs wo with programs which do direct
hard disk to video transfer./  On 80386 or 80386SX systems which do direct
hard disk to video transfers, the SCSIHA.SYS file must still be install.

When a SCSI tape drive is used, a device driver called SCSITAPE.SYS must be
installed in the CONFIG.SYS file if the drive is to be used in the MS-DOS
environment.  This file is also on the 700-4161 diskette.

BIOS Version 5.01S:

This Bios treats all SCSI hard drives as though they have 64 heads.  This
BIOS is only available as a upgrade from National Parts for the 250-4161
and 250-4161A boards.  In MS-DOS3.30.00 operation, this means that all of
the space on all SCSI drives can be accessed.

On 80386-based MS-DOS3.30.00 systems, the 700-4161 SCSIHA.SYS driver need no
longer be used with virtual mode programs wo with programs which do direct
hard disk to video transfer./  On 80386 or 80386SX systems which do direct
hard disk to video transfers, the SCSIHA.SYS file must still be install.

When a SCSI tape drive is used, a device driver called SCSITAPE.SYS must be
installed in the CONFIG.SYS file if the drive is to be used in the MS-DOS
environment.  This file is also on the 700-4161 diskette.

BIOS Version 4.05S:

This is a 16-head BIOS version.  In MS-DOSD 3.30.00 operation, this BIOS can
access all of the space on SCSI hard drives with a capacity less than 256 MEG;
it cannot access all of a SCSI hard drive with a capacity greater than 256 MEG.

On MS-DOS 3.30.00 systems, the 700-4161 SCSIHA.SYS driver need no longer be
used with virtual mode programs or with programs which do direct hard disk
to video transfers.

When a SCSI tape drive is used, a device driver called SCSITAPE.SYS must be
installed in the CONFIG.SYS file if the drive is to be used in the MS-DOS
environment.  This file is also on the 700-4161 diskette.

BIOS Version 5.05S:

This is a 64-head version that is available as an upgrade from National Parts.
 In MS-DOS 3.30.00 oeration, this means that all of the space on all SCSI
drives will be available.

On MS-DOS 3.30.00 systems, the 700-4161 SCSIHA.SYS driver need no longer be
used with virtual mode programs or with programs which do direct hard disk
to video transfers.

When a SCSI tape drive is used, a device driver called SCSITAPE.SYS must be
installed in the CONFIG.SYS file if the drive is to be used in the MS-DOS
environment.  This file is also on the 700-4161 diskette.


Supported 16 and 64 Head Bios Roms:
┌───────────┬────────────────────────┬────────────────────┐
│           │ 16 Head BIOS ROMS      │  64 Head BIOS ROMS │
├───────────┼────────────────────────┼────────────────────┤
│Board      │ 2.0C    4.03S    4.05S │   5.01S     5.05S  │
├───────────┼────────────────────────├────────────────────┤
│250-4161   │ yes     yes      yes   │   yes       yes    │
│250-4161A  │ no      yes      yes   │   yes       yes    │
│250-4161B  │ no      no       yes   │   yes       yes    │
└───────────┴────────────────────────┴────────────────────┘


(SMM/jlc-03/27/94)