EMERSONIPMC7126E/7616E I/O Module

configurations, many of which are not applicable to either module. This chapter describes those 

aspects of the specification that are unique to both modules.

PCI Local Bus

The on-board PCI devices on the IPMC712 and the IPMC761 are the PCI-to-ISA Bridge and 

the SCSI controller.

The PCI-to-ISA Bridge (PIB)

The PCI-to-ISA Bridge (PIB) provides the bridging functions between PCI local bus and the ISA 

local resource bus. Other features contained in the PIB are:

■ 8259 Interrupt Controller

■ ISA DMA support

■ Timers and counters

The SCSI Controller

The SCSI controller’s clock speed is 40 MHz. The presence of the SCSI device can be positively 

determined by reading the Device ID PCI Configuration Register 0x02 - 0x03. The Device ID is 

0x0012.

The General Purpose I/O (GPIO) pin assignments for the SCSI Controller are shown in the 

table below. A 1x4 switch (S1) is provided to configure GPIO pins 2 and 3. The factory default 

setting shall be for Ultra-Speed and Ultra-Wide SCSI.

The General Purpose I/O (GPIO) pin assignments for the SCSI Controller are shown in the 

table below. A 1x4 switch (S1) is provided to configure GPIO pins 2 and 3. The factory default 

setting shall be for Ultra-Speed and Ultra-Wide SCSI.

SW1-P1 controls GPIO2 (Ultra/FAST SCSI) and SW1-P2 controls GPIO3 (Wide/Narrow SCSI 

bus. SW1-P3 and SW1-P4 are No Connect. Select the SCSI characteristics of your 

configuration according to the following table:

Table 3-1. GPIO Pin Assignments 

GPIO Pin Direction Level Usage

 GPIO1_MASTER_l output 1 SCSI LED; SCSI is not MASTER.

 0 SCSI is MASTER.

 GPIO2 input 1 SCSI speed; selectable by switch S1.

S1:1 OFF selects Ultra 

 0 S1:1 ON selects FAST (default).

 GPIO3 input 1 SCSI bus width; selectable by switch S1.

S1:2 in OFF selects Wide-SCSI.

 0 S1:2 in ON selects Narrow-SCSI.

 0, 4, 5, 6, 7, 8 - - Not used

Table 3-2. SCSI Speed/Width Settings Using GPIO2:[1,2]

Figure 3-1. GPIO Switch Settings (S1)

SW1-P1 controls GPIO2 (Ultra/FAST SCSI) and SW1-P2 controls GPIO3 (Wide/Narrow SCSI 

bus. SW1-P3 and SW1-P4 are No Connect. Select the SCSI characteristics of your 

configuration according to the following table:

Width of Bus Ultra (P1 OFF) Fast (P1 ON)

Wide (16-bit) SCSI bus (P2 OFF) 40MB/second 20MB/second

Narrow (8-bit) SCSI bus (P2 ON) 20MB/second 10MB/second