IBM AT 5170 Technical Reference page 19

The type 1 system board is approximately 30.5 by 35 centimeters
(12 by 13.8 inches). The type 2 system board is approximately
23.8 by 35 centimeters (9.3 by 13.8 inches). Both types of
system boards use very large scale integration (VLSI) technology
and have the following components:
• Intel 80286 Microprocessor
• System support function:
Seven-Channel Direct Memory Access (DMA)
Sixteen-level interrupt
Three programmable timers
System clock
• 64K read-only memory (ROM) subsystem, expandable to
128K
•
A 512K random-access memory (RAM) Subsystem
.~
•
Eight input/output (I/O) slots:
Six with a 36-pin and a 62-pin card-edge socket
Two with only the 62-pin card-edge socket
• Speaker attachment
• Keyboard attachment
• Complementary metal oxide semiconductor (CMOS)
memory RAM to maintain system configuration
•
Real-Time Clock
•
Battery backup for CMOS configuration table and
~
Real-Time Clock
System Board 1-3