1. Introduction
ÛZIATECH
12
Functional Block Diagram
®
ZT 8907
Counter/
Timer I/O
Interrupt
Inputs
Centronics
Port
24-Point
Parallel I/O
Two 16C550
Serial Ports
AC/DC
Power Detect
25 to
100 MHz
486 CPU
8 KB
Cache/
16KB
Cache
(DX4)
Dynamic
RAM
(up to
32 Mbytes)
Flash
Memory
(up to
4 Mbytes)
PCI
Local Bus
Expansion
IDE
Subsystem
Counter/Timers
Watchdog
Timer
Interrupt
Controllers
Bus Interface
(Single and Multiple Master Operation)
DMA
Controllers
Battery-Backed
SRAM (128 Kbytes)
Battery
Real-Time
Clock
ZT8907
STD Bus Interface
In an STD 32 system, data transfers are dynamically sized for either 8 bits or 16 bits.
STD 32 compatible memory and I/O boards are dynamically sensed to determine the
width of the data transfer.
In addition to 16-bit data transfers, the STD 32 system provides the platform needed for
multiple master operation. In a multiple master system, up to seven ZT 8907 boards
share STD bus resources with a fixed or rotating priority granted by an external bus
arbiter, such as the ZT 89CT39. If used, the ZT 89CT39 must be Revision D or higher.
See Chapter 3, "
," for a detailed description of the ZT 8907 interface
to the STD bus architecture.