
Chapter 1. Introduction
7
Interrupts
Two enhanced 8259 style interrupt controllers provide a total of 15 interrupt inputs. Interrupt controller
features include support for level-triggered and edge-triggered inputs, fixed and rotating priorities,
and individual input masking. Interrupt sources include counter/timers, serial I/O, real-time clock,
keyboard, printer, and multiple master communications. There are also five frontplane and five
backplane interrupt sources. Enhanced capabilities include the ability to configure each interrupt level
for active high going edge or active low level inputs.
All interrupt routing for STD 32 and frontplane interrupt sources is done through the BIOS SETUP
utility, allowing jumperless configuration (See "ZT 8905 SETUP" in Chapter 2 for more information).
The PCI enumerator can also configure up to four PCI interrupts.
See Chapter 4, "Interrupt Controller," for more information on the ZT 8905's two interrupt controllers.
This chapter summarizes and illustrates the interrupt sources and the interrupt controllers'
programmable registers.
Counter/Timers
Three 8254 style counter/timers are included on the ZT 8905 as defined for the AT. Operating modes
supported by the counter/timers include interrupt on count, frequency divider, square wave generator,
software triggered, hardware triggered, and one shot. See Chapter 5, "Counter/Timers," for more
information.
DMA
Two enhanced 8237 style DMA controllers provide a total of one STD 32 and three frontplane DMA
channels for data transfers between system I/O and local memory. The DMA channels support
STD 32 bus DMA slaves by managing the data transfers between the slaves and local memory.
Additional features of the DMA channels include auto initialization, address increment or decrement,
and software DMA requests. Enhanced DMA capabilities include support for higher speed
(8 Mbyte/sec) transfer types and 32-bit memory addressing.
One DMA channel is available through the STD bus BUSRQ* and BUSAK* signals. This is
configurable as either an 8-bit DMA channel (DRQ2) used primarily for floppy disk operation or a 16-
bit DMA channel (DRQ5). Three additional DMA channels are available through the Multi-I/O
connector.
See Chapter 6, "DMA Controller" for more information.
Watchdog Timer
The watchdog timer optionally monitors system operation. Failure to strobe the watchdog timer within
a set time period results in a system reset. Chapter 12, "Watchdog Timer" explains operation of the
watchdog timer and includes code for arming and strobing the timer.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Содержание ZT 8905
Страница 13: ...Contents Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...
Страница 15: ...Tables Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...
Страница 163: ...Index xxxvi Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...
Страница 164: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...