What to do if the picture is distorted on Radio Shack TRS-80?
If your Radio Shack Desktop picture is distorted even after fine-tuning adjustments, and you lack a Spectrum Analyzer, consider replacing the modulator unit.
Why clock does not appear at TP2 on Radio Shack TRS-80 Desktop?
If the clock does not appear at TP2 on your Radio Shack Desktop, it might be a modulator issue. Check the +5 volts at pin 11 and the 3.579 MHz clock at pin 1 of MC1372.
What to do if Radio Shack Computer Hardware display is garbled?
If your Radio Shack Computer Hardware display is garbled, ensure the telephone handset is firmly seated in the rubber cushions and that the baud rate is correct (both local and remote computer systems must send data at the same rate, 300 baud or less). Also, check if the received signal is too weak or noisy. If the remote modem is in answer mode, pick up the handset and listen for a clean tone. If you hear additional tones, dialing pulses, static noise, or voice sounds, the data may be garbled; try re-placing the call.
How to fix READY LED if it is off on Radio Shack Computer Hardware?
If the READY LED is off on your Radio Shack Computer Hardware, first ensure the power is on and the handset is properly positioned in the rubber cushions with the cord toward the RS-232-C cable end. Verify that the mode switches are set correctly. When communicating with a time-share computer, the modem must be in Originate mode. When communicating with another TRS-80, the mode selection must be agreed upon before data transmission, with one modem in Answer mode and the other in Originate mode. For data communication, the duplex switch must be in either Full or Half position (not TEST). Finally, check if the modem at the other end is compatible with the TELEPHONE INTERFACE II according to its specifications.
Why does my Radio Shack Computer Hardware display double characters?
A double character display on your Radio Shack Computer Hardware might occur if the system is in half-duplex mode. If the remote computer echoes all characters, the TRS-80 system must be in full-duplex mode. If the communication system is half-duplex (no echo), either RS-232-C or TELEPHONE INTERFACE II (but not both) must be in half-duplex.
General| Release Year | 1977 |
|---|---|
| CPU | Zilog Z80 |
| CPU Speed | 1.77 MHz |
| RAM | 4 KB (expandable to 48 KB) |
| Model | TRS-80 |
| Display | Monochrome CRT |
| Display Resolution | 64 x 16 characters |
| Storage | Cassette tape (optional disk drive) |
| Operating System | TRS-80 Level I BASIC (Level II BASIC with ROM upgrade) |
| Ports | Cassette |
Steps to prepare the TRS-80 for use, including connecting peripherals and powering on.
Explains what a computer program is and introduces BASIC for the TRS-80.
Demonstrates adding lines to a program and the importance of line numbering for modifications.
Explains common error messages like WHAT? and SORRY and how to interpret them.
Introduces math operators and solving simple problems using equations like distance = rate * time.
Introduces exponential notation for scientific calculations and its representation in BASIC.
Details how parentheses affect calculation order and introduces the standard order of operations in BASIC.
Introduces relational operators (=, >, <, etc.) used for comparisons in IF-THEN statements.
Explains the IF-THEN statement for making decisions and controlling program flow.
Describes how to use the INPUT statement to get user input from the keyboard.
Explains how to use the computer as a calculator by omitting line numbers for commands.
Details the process of saving programs onto cassette tape using the CSAVE command.
Explains how to load programs from cassette tape using the CLOAD command.
Introduces the FOR-NEXT loop structure for repetitive tasks and controlling program execution.
Explains how to use the STEP function to control the increment or decrement value in FOR-NEXT loops.
Demonstrates creating time delays in programs using FOR-NEXT loops.
Explains how to use the TAB function for precise formatting of output columns.
Introduces the concept of nesting loops within each other for complex repetitive tasks.
Explains the INT function for rounding numbers to the nearest whole integer.
Details how IF-THEN and GOTO statements control program flow based on conditions.
Introduces the ON-GOTO statement for multiple branching based on a variable's value.
Explains how to store and retrieve data within a program using DATA and READ statements.
Explains the ABS function for calculating the absolute value of a number.
Introduces shorthand commands and statements to simplify typing and program entry.
Explains the RND function for generating random numbers and its variations.
Details the SET and RESET commands for controlling individual graphics points on the screen.
Introduces the PRINT AT statement for positioning text output at specific screen coordinates.
Explains the concept of arrays for storing and managing collections of data.
Describes the POINT statement for checking the status of a specific graphics location on the screen.
Introduces basic flowchart symbols used for planning program logic visually.
Explains the use of logical operators * (AND) and + (OR) for complex conditional statements.
Details the concept of subroutines and how to call them using GOSUB and RETURN.
Introduces trigonometric subroutines like TAN, COS, SIN, and their applications.
Outlines a systematic approach to identify issues as hardware, operator, or software problems.
Lists common programming mistakes that lead to computer-detected errors.
Provides the solution for Exercise 3-1, focusing on the PRINT statement for output.
A program to grade student tests based on entered answers and correct responses.
Details the subroutine for calculating square roots, including input and output requirements.
Explains how to save and load data using cassette files with PRINT # and INPUT #.
Outlines the three stages of the test program: function, RAM, and display checkout.
Details the specifications for connecting a cassette recorder to the computer.
Provides specifications for connecting a video display to the computer.
Lists BASIC commands, their purpose, and where they are described in the manual.
Lists BASIC statements, their purpose, and corresponding examples.
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