IBM 5150 Technical Reference

Other Circuits
,..-...,., Speaker Circuit
The sound system has a small, permanent magnet, 57.15 mm
(2-1/4 in.) speaker. The speaker can be driven from one or both
of two sources:
•
An 8255A-5 programmable peripheral interface (PPI) output
bit. The address and bit are defined in the
"I/O Address
Map".
• A timer clock channel, the output of which is programmable
within the functions of the 8253-5 timer when using a
1.19-MHz clock input. The timer gate also
is controlled by an
8255A-5 PPI output-port bit. Address and bit assignment are
in the
"I/O Address Map".
PPI Bit 1. 1/0 Address Hex 0061_
1.19 MHz
AND
Clock Low
To
-
In2
Timer Clock Out 2
r---.
- Driver
t--
Pass
i'-'Speaker
-
Gate 2
Filter
PPI Bit O. 1/0 Address Hex 0061
Speaker Drive System Block Diagram
Channel 2 (Tone generation for speaker)
Gate 2 - Controller
by 8255A-5 PPI Bit
(See
1/0 Map)
Clock In 2 - 1.19318 -
MHz OSC
Clock Out 2 - Used
to drive speaker
,..-...,., Speaker Tone Generation
System Board 1-25

IBM 5150 Specifications

General

Brand	IBM
Model	5150
Category	Desktop
Language	English