PC104P-SIO4BX User Manual, Revision: 0
General Standards Corporation
8302A Whitesburg Drive Huntsville, AL 35802, Phone: (256) 880-8787
CHAPTER 2: LOCAL SPACE REGISTERS
2.0
Register Map
The SIO4BX is accessed through three sets of registers – PCI Registers, USC Registers, and GSC Firmware
Registers. The GSC Firmware Registers and USC Registers are referred to as Local Space Registers and are
described below. The PCI registers are discussed in Chapter 3.
The Local Space Registers are divided into two distinct functional register blocks – the GSC Firmware Registers and
the USC Registers. The GSC Firmware Registers perform the custom board control functions, while the USC
Registers map the Zilog Z16C30 registers into local address space. The register block for each USC channel is
accessed at a unique address range. The table below shows the address mapping for the local space registers.
Local Address Range
Base Address Offset
Register Block Description
0x0000 – 0x00FF
0x0000
GSC Firmware Registers
0x0100 – 0x013F
0x0100
Channel 1 USC Registers
0x0140 – 0x01FF
Reserved
0x0200 – 0x023F
0x0200
Channel 2 USC Registers
0x0240 – 0x02FF
Reserved
0x0300 – 0x033F
0x0300
Channel 3 USC Registers
0x0340 – 0x03FF
Reserved
0x0400 – 0x043F
0x0400
Channel 4 USC Registers
The GSC Firmware Registers are detailed in Section 2.1. The USC Registers are briefly touched on in Section 2.2 of
this manual, but are described in much greater detail in the Zilog Z16C30 Users Manuals.
