A. Board Configuration
ÛZIATECH
89
However, some STD 32 systems define INTRQ4* for VBAT (battery backup) on the
STD bus. When that is the case, select INTRQ* for the multiple master interrupt (W1B =
In) and remove cuttable trace
CT48.
W1A
W1B
CT48
Function
In
Out
In
INTRQ4* is multiple master interrupt
Out
In
Out
INTRQ* is multiple master interrupt
W2 (PROM/SRAM Selection)
W2 defines the three functions of socket U17. Proper configuration of W4 is also
required. See the "
" table on the following page.
1. BIOS Recovery: If the ZT 8907's BIOS becomes corrupted, recover it by installing
jumper W2A and installing a PROM programmed with the BIOS into socket (U17).
See the "
" topic in Chapter 16 for step-by-step instructions.
2. User Static RAM: Installing jumper W2B and installing a 128 Kbyte SRAM module
into socket U17 provides four 32 Kbyte pages of SRAM memory for use by user
programs. SRAM is selectable through bits 3 and 4 of System Register 2 (E4h). In
screen 2 of the BIOS SETUP utility, set the parameter "Memory Range D8000 –
DFFFFh" to "PCI" in order to access the on-board SRAM. To conserve battery life,
always battery back this SRAM by making sure jumper W4A is installed. See the
"
" topic in Chapter 16 for step-by-step instructions.
3. STAR SYSTEM Video Emulation SRAM: When the ZT 8907 is used in a STAR
SYSTEM and is sharing a video card with other CPUs, remove all jumpers from W2
and install a 128 Kbyte SRAM module in socket U17. To conserve battery life,
always battery back this SRAM by making sure jumper W4A is installed. See the
"
STAR SYSTEM Video Emulation SRAM
" topic in Chapter 16 for step-by-step
instructions.
Function
Installed in U17
W2A
W2B
State of W4
BIOS Recovery
PROM (ZT 95204) In
Out
Position B jumpered
†
User Static RAM
128 Kbyte SRAM
Out
In
Position A jumpered
†
STAR SYSTEM Video 128 Kbyte SRAM
Out
Out
Position A jumpered
Emulation SRAM
Note:
In no case should W4 be totally unjumpered.
†
Factory default configuration