Vector 4 - Page 92

VECTOR ¢4
TECHNICAL INFORMATION
SECTION V - OVERVIEW OF THE I/0
SYSTEM
Summary: The I/O System provides the link which connects external
devices with the previously discussed SBC Subsystems. The I/O System
consists of parallel and serial ports, various port decoders and the
Expansion Slots.
The 1/O System is described by referencing the following blocks (subsystems) from
the SBC Block Diagram and Schematic:
Block
Diagram
Number(s)
9, 14
11,16
10, 15
13, 19
09-01-82
Schematic
Notation
D1
D13
D2
D3
D4
D5
D6
D7
Subsystem
Description
Keyboard Interface: A USART whieh links the I/0
System with the Keyboard System. Section VI gives a
description of external keyboard connector.
Keyboard Cloek: A clock provides the internal clocking
signal for the Keyboard Interface.
Serial Printer Interface: A USART and a DB-25
connector. The USART is configured as a DCE device so
that it can communicate with a DTE device.
Modem Interface: A USART and a DB-25 connector. The
USART is configured as a DTE device so that it can
communicate with a DCE device.
Tone Generator Interface: A specially designed tone
generator chip and a speaker.
Port Decoder 0: A decoder used to decode a variety of
port addresses. It generates 8 port signals which are
used by several SBC Subsystems.
Port Decoder 1: A decoder used to decode a variety of
port addresses. It generates 8 port signals (6 are used by
the SBC).
Timer: A programmable interval timer chip (8253) which
is used to generate baud rates and a interrupt.
7200-0001 | II 5-1