IBM 5150 Technical Reference

The speaker connection is a 4-pin Berg connector. See "System
Board Component Diagram," earlier in this section, for speaker
connection or placement.
Pin
Function
1 Data
2 Key
3 Ground
4 + 5 Volts
Speaker Connector
The speaker drive circuit is capable of about 1/2 watt of power.
The control circuits allow the speaker to be driven three ways:
(1) a direct program control register bit may be toggled to
generate a pulse train; (2) the output from Channel 2 of the
timer/ counter device may be programmed to generate a
waveform to the speaker;
(3) the clock input to the timer/counter
device can be modulated with a program-controlled
I/O register
bit. All three methods may be performed simultaneously.
1-26 System Board

IBM 5150 Specifications

General

Processor	Intel 8088
Clock Speed	4.77 MHz
RAM	16 KB - 256 KB
Manufacturer	IBM
Model	5150
Release Year	1981
Storage	5.25-inch floppy drives
Graphics	MDA or CGA
Operating System	IBM PC DOS
Ports	Cassette, keyboard
Expansion Slots	5