Radio Shack TRS-80 Service Manual page 10

SYSTEM OVERVIEW
The Aadio 5tIack TASSO Model III Miaocomputer is an enhanced venion of Aadio 5tIack's popular TRsaO Microcom-
puter (Model
n.
The TAs-80 Model III is sohware eompatible with the Modell
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thillt ownenof either system can take
adll8ntilge of the large number of programs available.
Features of the TAS-80 Model III which are common to the TR5-80 Modell include:
• Availability of Level lor Level II BASIC in ROM
• Full size typewriter style keyboard
• A 12-inch video display
• Built·in cassette interface
• Character display of 16 lines of 64 characters
• Graphics under control of BASIC (128 H x 48 VI
• UL reoognized construction
In addition. tne Model III has the following standard features:
• 12-«.ey numeric keypad for rapid entry of numbers
• Augged cabinet housing keyboard. electronics, video display. and power supply
• Direct drive video monitor for improved resolution
• Internal power supply
• Parallel printer port for
USll
with Aadio 5tIack printers
several other features are available when Level II BASIC is used; features such as: real time clock, upper and lower case
characters, RAM internally expandable to 48K bytes, I/O l)Or\ for peripheral expansion. and cassette interface available
with 500 aoo 1500 baud rates.
Optional peripherals for the TAS-aO Model III include disk drives (two built·in, two external) with double density for
increased storage capacity. and a huilt·in R5-232 serial interface for communications and peripheral interface.
The Block Diagram shows the various internal components and connections of the Model III Microcomputer.
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