Texas Instruments 99/4A - Page 9

INTRODUCTION
The TI 99/4 Home Computer was initially presented at the Consumer
Electronics Show in June 1979 by Texas Instruments. The TI 99/4 is a
TMS 9900-based microprocessor system. Presently, the 99/4A mainframe
is being manufactured by the Consumer Products Division of Texas
Instruments Inc. in Lubbock, Texas.
The TI 99/4A has many key features. Some of these features, include
16-color graphics, music and sound over four octaves. The TI 99/4A
al so makes use of an expanded TI Basic. This feature plus the
capability for up to 72K bytes of memory (16K RAM internal, 26K ROM,
and up to 30K ROM interfaced via the Command Module peripherals) make
the TI 99/4A Home Computer a very powerful tool. These key features
and the general operation of the TI 99/4A will be presented in the
following pages.
SYSTEM BLOCK DIAGRAM:
The TI 99/4A Home Computer effectively combines each of the individual
features of the unit into a complete and complex system. The basic
blocks of the system include the CPU, sound generation, video display,
I/O control, plus timing and control logic. These features are
interfaced to produce the complete microprocessor system. The system
block diagram of the TI 99/4A is shown in Figure 1, p. 2.
1