IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

The 16KB Memory Expansion Kits allow you to increase the memory
size ofyour IBM p.ersonal Computer. The base system comes standard
with 16KB of memory. Up to three 16KB Memory Expansion Kits
may be installed to increase the memory size to 64KB. Memory can be
further increased to 256KB with additional memory options once these
three Expansion Kits are installed.
~e Expansion Kits plug into the System Board and must be installed
sequentially. They do not occupy any of the five System Expansion
Slots.
The 32KB and 64KB Memory Expansion Options permit you to
increase memory capacity beyond 64KB. Multiple 32KB and 64KB
Memory Expansion Options may be installed as long as System
Expansion Slots are available. A maximum of three 64KB memory
options may be installed for a total of 256KB of memory.
The 32KB and 64KB Memory Expansion Options require a System
Expansion Slot in the System Unit. The first 64KB on the System
Board is required before 32KB and 64KB Memory Expansion Options
can be installed.
The Asynchronous Communications Adapter provides a channel to
data processing or input/output devices outside of your immediate
~system. These can be connected by telephone using a plug-in modem,
qr directly by cable when the device is nearby.
This option utilizes the RS232C asynchronous (start-stop) interface
permitting attachment to a variety of devices including a large "host"
computer or another IBM p.ersonal Computer.
This option supports 50 to 9600 BPS transmission speeds. One 25 pin
"D" shell, male type connector is provided to attach various peripheral
devices. A "current loop" interface is located in the same connector,
and a jumper block is provided to manually select either the voltage or
the current loop interface.
The Asynchronous Communications Adapter requires a System
Expansion Slot in the System Unit. An external modem is required for
telephone line transmission.
The Game Control Adapter permits the attachment of user-supplied
joysticks or paddles. Two joysticks and up to four paddles may be
~. attached. IBM does not manufacture either the joysticks or the paddles.
This option provides connectors for joysticks or paddles and requires a
System Expansion Slot in the System Unit.
A block diagram of the system is on the following page (1-4).
1-3