Specifications

SCSIID Jumperlng
Three jumper pin pairs (W23-W25) normally are used to provide a three bit SCSI Initiator
10, for use by the board's ROM-BIOS and other support software. The jumper assignments
are shown in-Table 2-23. These jumper pins can be used for other purposes if tbe SCSI inter-
face
is not required. (See Chapter 5).
Table 2-23. SCSI Initiator ID Jumpering
SCSI Bus ID W25 W24 W23
0 short short short
1 short short
open
2
short
open short
.
3
short
open open
4
open short short
5
open
short
open
6 open
open
short
7 open
open
open
Default: 7
open
open
open
External Termination Power Option
A jumper option (W4) allows the connection of +5 volts termination power to the SCSI bus
TERMPWR signal (pin 26). Please observe the following caution regarding this function:
Caution
No termination power protection diode is provided on the
board. Consequently, W4 IIIIUt NOT be installed if any
other bllS devke suppliu terminatioII power, or damage to
1M boanllflay tesrdL
The default jumpering of this option is unshorted; i.e., termination power is not normally
supplied by the Little Board/PC.
Enhanced SCSI Speed Option
The SCSI support within the ROM-BIOS offers a "SCSI Halt Mode" option, which can be
enabled by shorting two configuration jumpers on the board. When SCSI Halt Mode is
enabled, the processor halts while SCSI DMA read/write data transfers are occurring,
allowing the
DMA channel full bus bandwidth. SCSI Halt Mode can provide as much as 25
percent improvement
in SCSI data throughput rate, depending on the specific application.
2-24