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

SECTION I.
HARDWARE OVERVIEW
The IBM Personal Computer has two major elements; a System Unit
"..-..." and a keyboard. In addition, a variety of options are offered including
one or two 5-1/4" Diskette Drives with adapter which can be housed
inside the System Unit, an IBM Monochrome Display, an 80 CPS
Matrix Printer, two display adapters, storage increments to 256 KB, an
Asynchronous Communications Adapter, Printer Adapter and a
Game Control Adapter.
The System Unit is the heart of your IBM Personal Computer system.
The System Unit houses the microprocessor, Read-Only Memory
(ROM), Read/Write Memory, Power Supply, and System Expansion
Slots for the attachment of up to five options. One or two 5-1/4"
Diskette Drives can also be mounted in the system Unit providing
160KB of storage each.
The System Board is a large board which fits horizontally in the base
of the System Unit and includes the microprocessor, 40KB ROM and
16KB memory. The memory can be expanded in 16KB increments to
64KB. The System Board also includes an enhanced version of the
Microsoft BASIC-80 Interpreter without diskette functions. The
BASIC Interpreter is included in the ROM. The System Board also
permits the attachment of an audio cassette recorder for loading or
saving programs and data.
The System Unit power system is a 63.5 watt, 4 level DC and 120 AC
unit. It is a switching regulator design" allowing for light weight and
high efficiency. The DC power capacity is designed to support an
expanded system.
The 5-1/4" Diskette Drive Adapter fits into one of the five System
Expansion Slots. This attachment supports two internal drives. The
5-1/4" Diskette Drive Adapter uses write precompensation and a
phase lock loop for clock and data recovery.
The 5-1/4" Diskette Drive permits the IBM Personal Computer to
read, write and store data on 5-1/4" diskettes. Each diskette stores
approximately 160KB of data. Two of these drives may be installed
internally in the System Unit.
The keyboard is attached to the System Unit with a light-weight, coiled
cable. The keyboard features 83 keys, and offers commonly used data
and word processing functions in a design combining the familiar
typewriter and calculator pad layouts.
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