BT-646S/D SCSI Adapter for MicroChannel Systems
  32-bit bus master DMA transfers of up to 40MB/second across the MC bus, up to 10 MB/sec synchronous and up to 7 MB/set asynchronous SCSI data transfers. Support for up to seven SCSI devices, hard drives with up to 8GB capacity each. Enhanced SCSI-2 features: scatter-gather, disconnect-reconnect, and command-tag queuing 

BT-646x Host Interface Microprocessor
   A 20MHz Intel 80186 16-bit MPU is used to supply the speed for low command overhead. This MPU coordinates all activity on the BT-646S/D under the direction of the board�s firmware, including initialization, command decoding, interrupt generation, and control of the data flow among the board�s components.

Differences between and 646S and BT-646D
     BT-646S Single-ended active termination , BT-646D Differential termination 

Multitasking Operation
   For operating systems such as UNIX, NetWare, and OS/2, the mailbox protocol of the BT-64x provides true multitasking operation. Through the use of a mailbox structure, the BT-64x can support up to 255 tasks with minimum host processor intervention. Onboard firmware controls all of the SCSI activity that a task requires, including the Arbitration, Selection, Disconnection, Reconnection, and command completion status. This same mailbox protocol supports both initiator and target mode operation permitting high speed host-to-host communication and scatter-gather data transfers.

Disk Drive Power Connector
   A 4-pin disk drive power connector (J4) is located at the top edge of the BT-64x board next to the SCSI connector Jl. This connector provides +12V and +5V power.
   Note: The BT-64x brings the 12 volt power supply to the 4-pin power connector (14) via three gold fingers on the edge connector. The power rating of the Micro Channel edge connector on the12 volt is one ampere per finger. Consequently, fhe maximum power allowed from the 12 volts (Pin 1 of J4) is three amperes. Because certain large SCSI drives may require more than three amperes when their motors are spinning up, BusLogic recommends that this connector not be connected to these large SCSI drives.
   Based on the power rating of the SCSI drives, if is generally recommended that
this power connector not be daisy chained to multiple drives.

Disk > 1 GB and not SC0 UNIX.
    In the DOS environment, INT 13 calls are routed through the BT-64xA/S/D�s ROM BIOS. This on-board BIOS intercepts host interrupt 13H calls and dispatches a command to the BT-64x for all host to SCSI disk accesses. When the >lGB option is turned on, the BT-640A BIOS can access up to 8 GBytes per disk. Otherwise, it can only access the first 1 GBytes even if the formatted disk capacity is greater than 1GByte. This 1GByte restriction does not apply to other operating systems, such as NetWare, UNIX, SC0 UNIX 3.2.4, or OS/2 if the operating system can boot without accessing > 1 GBytes. If the operating system�s bootable image resides below 1 GBytes then it can boot via Interrupt 13H. Once any of these operating systems are booted, the disk accesses are not routed through Interrupt 13H and the operating system can access the entire disk space even if the > 1 GB option is not turned on.
   Under SC0 UNIX 3.2.2, the >lGB option must be turned off because the operating system itself has a 1 GByte limitation. Otherwise, disk images may be corrupted when the 1 GByte boundary is reached. For SC0 UNIX 3.2.4, the operating system does not impose the 1 GByte limit, and this
option can be turned on or off accordingly. Consequently, the >lGByte support must be turned on under the following two conditions: (1) the combined space of all the DOS partitions exceeds
lGByte, or (2) >lGByte disk accesses are required to boot the operating system. To enable the > 1 GB support, turn on this option. Note: If this option is changed, you must reformat the disk to avoid corrupting the existing file system.

BT-640A SCSI Adapter for MicroChannel Systems
Host Bus:   16 and 32-bit MCA  32-bit busmaster DMA transfers of up to 40 MB/sec
MPU:   8 MHz 80188 onboard microprocessor
SCSI Controller:  NCR 53C94
ASIC:  86C05 busmaster ASIC
SCSI Bus:  Up to 7 devices
           SCSI-2 command set compatible
           Up to 5MB/sec synchronous or asynchronous
Onboard termination:  single-ended 3  resistor packs (220/330 ohm)Term power supplied to bus
Firmware:  Mailbox structure supports multitasking and scatter/gather
BIOS:  Supports hard drive boot Up to 8GB storage capacity supported in BIOS

�This error is applicable to the BT-646 when single-ended SCSI drivers are connected to the differential SCSI bus.

BT-646D has RP6-RP13 differential termination
RP6, 8, 10 and 12 are 10-pin SIPs containing 5 isolated 150 ohm resistors (Bourns 4610X-2-151)
RP7, 9, 11 and 13 are 10-pin SIPs containing 9 bused 330 ohm esistors.(Bourns 4610X-1-331)

Update PROM for the 646 S/D
NOTE - You must have a EPROM burner.  BusLogic will NOT help with burning. It's up to YOU.
646s-336.zip    ROM Binaries for BT-646S: 3.36-4.70

Storage Dimensions
SDC1611; 16-Bit SCSI-1 Micro Channel Host Bus Adapter
SDC3211B; 32-Bit SCSI-1 Micro Channel Host Bus Adapter
SDC3211F; 32-Bit Fast SCSI-2 Micro Channel Host Bus Adapter
LANStor MCA RAIDCard; 32-Bit MCA F/W SCSI-2 RAID Controller

Term Power Fuse
   SDCxx11x and BT-64x use a Microlite Little Fuse that is 125v and 1/2 amps (Littel 27301.5 125V 1.5A or equivalent micro fuse). It is difficult to see that the fuse is blown so you will need to use a VOM to test for continuity. The fuse can blow if termination power settings are not correct on the SCSI devices or if you disconnect the SCSI cables while the card or SCSI devices have power. (Ed. Sure ain't kidding!)    

SDC Drivers
CONFG243.EXE - (111k)  .adf files for all Storage Dimensions SCSI adapters. Buslogic drivers are the same... The Readme file

Micro Channel RAIDCard - v2.0 (269K)  all the required files to support the -002 Micro Channel RAIDCard for OS/2 and NetWare. For use under NetWare, you must also have the LANStor Plus software. When unarchiving this file, use  the "-D" option to restore the directory structure.

LANStor5 - v6.10 (109k)  SCSI NLM for NetWare v3.11 - supports the SDC1611/3211x under NetWare versions 3.11. Not tested or certified using NetWare v3.12 or v4.xx.

LANStor Plus - v2.50 (114k)  SCSI NLM for NetWare v3.12 and v4.xx  most current version of LANStor for the SDC1611/3211x, and the SDC3231WS SCSI Adapters. It includes  LAPIS Plus which which is Artecon' ASPI layer (manager).

OS/2 Switches
This adapter driver supports all bus master type BusLogic SCSI Host Adapter products. The BTSCSI.ADD device driver supports the following BusLogic host adapters:
   o  BT-640A, BT-646S - Micro Channel SCSI Host Adapters
 Usually, ADD device drivers determine the parameters automatically. The following parameters are provided in case it is necessary to override the default parameter selection.

 BASEDEV= -- BTSCSI.ADD ------------------------------------------
                                +- /V   -+  Verbose mode
  ----------------------------------------------------------------|

            +- /A:n ------------------------+  Adapter number
                        |- /!DM -------------|  Disable DASD Manager
                        |      +- :unitlist -|    List of unit IDs
                        |- /!SM -------------|   Disable SCSI Manager
                        |      +- :unitlist -|     List of unit IDs
                        |- /TQ ----------------|
                        |        +- :unitlist -|
                        |- /BON:n -------------|
                        +- /BOFF:n ------------+