2. Getting Started
19
180000h-3FFFFFh
140000h-17FFFFh
100000h-13FFFFh
080000h-0FFFFFh
050000h-07FFFFh
010000h-04FFFFh
00E000h-00FFFFh
00D000h-00DFFFh
00C800h-00CFFFh
00C000h-00C7FFh
00A000h-00BFFFh
000000h-009FFFh
RESERVED
FLASH #0
FLASH #1
STD BUS EXPANSION
RESERVED
EXTENDED RAM
SYSTEM BIOS
LOCAL RAM DRIVE
STD BUS EXPANSION
VIDEO BIOS
VIDEO RAM
SYSTEM RAM
STD BUS EXPANSION
EXPANSION MODULE
Memory Address Map
I/O CONFIGURATION
The ZT 8904 addresses up to 64 Kbytes of I/O using a 16-bit I/O address. The I/O map
is programmable through the CPU configuration registers. The I/O map architecture
selected for the Ziatech Industrial BIOS architecture is shown in the "
I/O Address Map
"
figure following.
STD bus expansion I/O is transferred at a rate of up to 1 Mbyte/second for 8-bit data
and 1.5 Mbytes/second for 16-bit data. The ZT 8904 supports the STD bus wait request
signal, WAITRQ*, to interface to I/O boards with longer access time requirements than
those defined by zero wait state STD 32 specifications. The STD bus I/O expansion
signal, IOEXP, is also supported. The IOEXP signal is automatically driven low over the
I/O address range FC00h to FFFFh. Application software should use this address range
to access STD bus I/O boards decoding IOEXP and fewer than 16 bits of address to
prevent the board from being redundantly mapped throughout the 64 Kbyte I/O address
space. During local I/O operations, the STD bus is held static to decrease system
electrical noise and power consumption.