Tandy 1000 Technical Reference Manual

Tandy 1000
Technical Reference Manual
CUSTOM LOGIC
CIRCUITS
TYPE SN76494. SN76496
PROGRAMMABLE TONE/NOISE GENERATOR
02801. NOVEMBER 1983
Vcc
03
CLK
D4
05
D6
07
AUDIO IN
N
DUAL-IN-L1NE PACKAGE
/TOPVIEWI
1 16
2 15
3 14
4 13
5 12
6 11
7 10
8 9
02
01
DO
READY
WE
CE
AUDIO OUT
GNO
• Each Circuit Contains
3 Programmable Tone Generators
• Programmable White-Noi .. Generator
• Programmable Attenuation
• Simultaneous Sounds
• TTL-C~mpetible
• Up to 500 kHz Clock Input for SN76494
and 4 MHz for SN76496
• External Audio Input for SN76496 Mey Be
Summed with Internany Generated Tones
description
The SN76494 digilal complex sound generalor is an integraled injeclion logic (I'll lone generalor designed 10 provide
low-cosl tone or noise generalion capability in microprocessor systems. The SN76494 is a dala-bus-based input-
oulpul peripheral device lhal interfaces lhe microprocessor lhrough eighl dala lines and lhree control lines.
The SN76494 is idenlicall0 the SN76496 excepl that lhe maximum clock input frequency for SN76494 is 500 kHz
and for SN76496 il is 4 MHz. A "divide-by-eighl" slage is deleled from the SN76496 circuitry so that only 4 clock
pulses are required to load the data into the SN76494. compared to 32 pulses for the SN76496.
Either of these devices may also be used as a replacment for the SN76489A in all applications if pin 9 is left open or
grounded. The output load must be limited to 10 mAo
When audio input is not desired in the SN76494 or SN76496. the audio input pin should be grounded.
functional block diagrem
PIl0DUCT PIlEVIEW Copyright C!1983 by Texas In51ruments Incorporeted
This document congin. tnfo"".tion on •
product under devetopment. T .... IM1ru·
tNftU ,...",.. the right to c:tt-nge or di.·
continue this DrOduc1 without notice.
TEXAS
INSTRUMENTS

Tandy 1000 Specifications

General

Processor	Intel 8088
Processor Speed	4.77 MHz
RAM	128 KB (expandable to 640 KB)
Operating System	MS-DOS 2.11
Manufacturer	Tandy Corporation
Release Year	1984
Storage	Single or double 5.25" floppy disk drive (360 KB), optional hard drive
Sound	Tandy 3-voice sound
Ports	Parallel, Serial
Graphics	CGA (Color Graphics Adapter)
Graphics Modes	320x200, 640x200