Specifications

System I/O
l DMA Channels:
8-bit operations - 4 channel
16-bit operations - 3 channel
l Programmable Timers: 3
l Vectored Interrupt Levels: 15
System Timing
l System Clock Speed
: 2QMHz (high)
8MHz (low)
l Clock Cycle Time
: 50ns (20MHz)
125ns (8MHz)
I/O Address Map
Hex Range
Device
000-01 F
020-03F
040-05F
060.06F
070.07F
080-09F
OAO-OBF
OCO-ODF
OEC-OED
OF0
OF1
OW-OFF
1 FO-1 F8
200-207
278-27F
8237A-5 DMA Controller #I
8259A Interrupt Controller #I
8254-2 Timer
8042 (Keyboard)
Real Time Clock NMI (Non-Ma&able Interrupt) Mask
74LS612 DMA Page Register
8259A Interrupt Controller #2
8237A-5 DMA Controller #2
Chipset register value setting
Clear Math Coprocessor Busy
Reset Math Coprocessor
Math Coprocessor
Fixed Disk
Game l/O
Parallel Printer Port 2
A-4 Specifications