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Last Updated
03/31/2019
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Detailed entries for one subject from the INDEX TO HOW TO DO IT INFORMATION. |
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KEYBOARD x KEYPAD xx COMPUTER INPUT & OUTPUT How to interface a calculator hexadecimal keyboard to input data to a computer. Input to an 8008 microprocessor is featured. A remote terminal transmitter and receiver allows a keyboard to be operated up to 200 feet away from the microprocessor. Transmission is via twisted pair cable for keyboard and coaxial cable for video monitor. Using a keyboard ROM. An explanation of the logic theory and general description of a ROM encoder which easily converts unencoded or non-ASCII keyboards to ASCII. Build a keyboard function decoder to turn your computer peripherals on and off from your keyboard. Let your fingers do the talking. Part 1. Add a non-contact touch scanner to your video display. Simply touch the screen of your video display to enter information, using this circuit. It is simpler than a light pen. Let your fingers do the talking. Part 2. Applications of the scanner. Level II BASIC program for TRS-80 system enables fast keyboard entry of hexadecimal code. Used in connection with the POKE function. Also includes a program to fill the screen of the TRS-80 with graphic characters. Z80 assembler program accepts keyboard input and checks it to determine its validity (is it error free?). A table is checked to see if the input matches a valid command. Product review of the Cherry Pro Keyboard. Alpha lock for your ASCII keyboard. Simple circuit shifts only the 26 alphabetic characters when enabled by a switch. Z80 code for uppercase to lowercase conversion in a keyboard-input subroutine. Build a low-cost remote data-entry terminal using a standard twenty-key hexadecimal pad and the MM57499 serial keyboard-encoder circuit. A lowercase to uppercase converter (hardware interface) requires a parallel interface between keyboard and computer. Tip: Cover the Apple II "reset" key with a clear plastic cover to keep from hitting it accidentally. Circuit for adding upper case/lower case shift to a DTL, RTL, or TTL keyboard. Build a versatile keyboard interface for the S-100. Accidental "reset" protection for the Apple II. Piggyback circuit board requires both CTRL and RESET to be pressed at the same time. Add a full-sized keyboard to Sinclair's ZX-80 computer. Serial circuit allows the keyboard for an IBM Personal Computer to be located 75 feet from the computer. Using IBM's marvelous keyboard. How to change the IBM keyboard to the Dvorak layout or use the keyboard with other computers and software. Add a high-quality keyboard to the Radio Shack Color Computer. Est. cost: $30. Redefining the Apple keyboard. With minor software modifications, you can rearrange the Apple II keyboard into a Dvorak layout. Foot control. Adding a foot-operated "control-character" key to your keyboard simplifies control sequences. Est. cost: $40. A keyboard input routine for IBM PC BASIC accepts only the set of characters and number of characters defined by the programmer. Keyboard and keystrokes. The electronic process of transferring a keystroke to a video screen. Part 1. Keyboard and keystrokes. Part 2. Add a keypad to your next project. What you should know to incorporate keypad-entry capability into computer and digital-electronic projects. Keypads made easy. A solder-and-scissors approach to making keypads for microcontrollers. Two accessories for the Sinclair/Timex computer. 1. Battery power to make the computer "portable" or as a back-up power supply. 2. Reset button. Multiple-character generation from your keyboard. A low-cost addition that will let you automatically repeat a character by holding a key. Keyboard encoding schemes. A guide to computer keyboard operation and solving interface problems. Keyboards. A look at the inner workings of a keyboard. How to build a home-brew ASCII keyboard controller. Part 1. How it works. The new Windows 95 keyboards. An overview of what those three extra keys are used for. Circuit for interfacing two keyboards to one computer. However, neither keyboard will receive any signals back from the computer. Tips on adapting a Wyse keyboard to replace an IBM keyboard. Tips on cleaning a computer keyboard. Converting a full-size TI99/4A keyboard (available from Radio Shack) for use with the Sinclair ZX-81 computer. Use that little old computer. How to hook up a remote keypad or switches to activate the primary keyboard of a Commodore VIC-20 computer. Use it for special applications (traffic survey, alarm system, etc.) Software keyboard interface. How to interface the bare keyboard from Datanetics Corp. to a Kim microcomputer with a minimum of hardware and a software routine of just 350 bytes. Est. cost for keyboard & interface: $22. Build a touch-response display. Add a row of 8 push buttons (switches) along the bottom of your video monitor. Use a simple circuit and read routine to sample the switches and use the input data to call up programs, play video games, etc. Read routine is in 8080 assembly language. CORRECTION to the article "Build your own ASCII keyboard" which appeared in the September 1977 issue of Kilobaud. One keyboard produces both Hex and ASCII by using this simple converter. Who needs a UART. Circuit for interfacing the parallel outputs from a keyboard to a serial input port. Uses only four standard chips, including the clock circuit. How to expand your KIM-1 system economically. How to interface the KIM to a video monitor and an ASCII keyboard, add more memory, add a cassette tape recorder, and add a power supply. Both hardware and software are described. Modify your COSMAC Elf microcomputer to interface with a keyboard and allow you to jump to any location in memory. The circuit requires no programming and uses no memory space. Routine to convert lower-case to upper-case when inputting data via a keyboard. Circuit and PC pattern for an 8-bit hexidecimal keyboard. Uses the National Semiconductor 74C922 keyboard chip as the encoder. Est. cost: $35. PET's keyboard grows up. Product review of Maxi Switch's full-size replacement keyboard for the PET computer. Caps lock, not shift lock. Circuit shifts only the alphabetic characters to upper case, but leaves the numbers and special characters alone. Lower-case for your Apple II. Part 1. Hardware modifications. Est. cost: $10. Lower-case for your Apple II. Part 2. Software needed to complete the modification. Converting Selectric keyboards from BCD to Correspondence code. Part 1. Mechanical aspects of conversion. Hex and ASCII. Interface circuit capable of accepting ASCII input from inexpensive keyboards, converting certain codes into hexadecimal, reformating hex code to strobe out 2 characters in parallel, and provide keyboard control of a CPU. Add a full-size detached keyboard to a PET computer. Estimated cost: $60. The old keyboard may still be used. Audio feedback for computer keyboards. Silent computer keyboards can result in more errors than a keyboard which produces a specific sound each time a key is pressed. Two circuits shown. Improving the OSI Challenger C2. Part 2. Video, cassette, and keyboard modifications. Interface for attaching a TASA Model 55 touch-activated keyboard to a computer. Circuit to eliminate accidental operation of the OSI C1 break key. Apple II circuit modification prevents accidental resets. Est. cost: $10. Student-proof your computer. How to add a special 7-key keyboard for use in a computer-aided instruction environment to eliminate the need for more sensitive and easily damaged keyboards. Modification to TBUG converts the numeric keypad into a very handy hexpad to facilitate data entry. Tip: Protect your keyboard from spilled liquids by placing into a clear plastic bag. You may use the keyboard without removing the bag. A relatively bounce-free switch responds directly to human touch and has no moving parts. Use in any situation where direct human input to a computer is desired without the need for a keyboard (music, handicapped, industrial control, etc.). Get some machine language programming practice by writing an uppercase-lowercase lock routine for your TRS-80 typewriter. "Number pad" subroutine written in BASIC for the Apple II computer. Lets you use one hand to enter numerical data by redefining the meaning of various keys. The intelligent toaster. Experiments in computer control. Design and construct your own video touch keypad. The intelligent toaster. Experiments in computer control. Continued discussion on designing and constructing touch circuits to input information. How to add a full-size keyboard to the Timex-Sinclair 1000 computer. How to program the Timex-Sinclair TS-1000 or ZX-81 computer in machine (hexadecimal) code. Includes instructions for adding a calculator keypad for input. Keyboard magic. Hexadecimal program for decoding the Commodore PET/CBM keyboard in order to expand the keyboard to include a reset button and a control key. How to program the fourteen keys of the Kaypro computer's numeric keyboard to act as dedicated function keys. A reconfigured keypad can make your computer easier to use, especially for word processing. A keyboard project that uses an EEPROM to store the key characters, making permanent changes simple. You can redefine keys to produce new keyboard layouts or assign multiple characters to a single key. How keyboards communicate with computers. Building the Radio Shack ASCII keyboard. Some tips on construction, troubleshooting, and a correction to the manual. How to use EPROMs for non-memory applications. Creating complex digital logic circuits with EPROMs simplifies electronic designing. Circuits include (1) keyboard translator, (2) keyboard-controller and (3) stepper-motor controller. Electronic AB switch for PC keyboards. Electronically switches between two keyboards while keeping both keyboards powered at all times. ASCII keyboard and encoder uses two IC's. Output is directly compatible with TTL, DTL, RTL, CMOS and PMOS integrated circuits. Est. cost: $40. Monitor program for the 8080 microprocessor so that programs can be entered from a keyboard. How to fully debounce low-cost keyboards. Inexpensive approach to properly interfacing calculator keyboards to microcomputers. Six CMOS digital integrated circuits include (1) automatic keyboard repeat and (2) contact debouncer. The versatile keypad. How to interface decimal and hexadecimal keypads to digital circuits. How to debounce the mechanical switch (key). Typical uses include computer data entry, electronic combination locks and a controlled pulse generator. Build a keyboard conversion circuit. Three ICs convert spst keyboard output into the column-row format used by decoder chips. A hexadecimal keyboard encoder. Part 1. Built on a perforated board, this unit uses 16 normally open pushbutton switches as the keypad. A hexadecimal keypad encoder. Part 2. Adding RAM to the encoder. How to add extra keyboards in tandem to an existing keyboard. Add a "key-down" audible signal to your computer keyboard. Simple circuit provides audible confirmation that a key has been struck properly. Simple BCD keyboard encoder circuit uses CMOS chips for low power consumption. Add doubles to your computer. Build this battery-powered unit which allows two simple key closures (switches) to input signals to a computer. Useful when two players must respond to a computer game. Circuit to hold and display (on LEDs) the ASCII code being generated by a particular key on a keyboard. Keyboard clean-up. How to disassemble and thoroughly clean a computer keyboard. Alarm projects and keypad interfaces. (1) Warning system isolated from main power source. (2) System-tripped indicator. (3) Time-keeping circuit to remind someone to take a medication. (4) Interface for low-cost telephone-like keypad produces a logic output that identifies the key that has been pressed. (5) Standard telephone-type keypad will operate a relay if the correct four-digit code is entered. Designing a keyboard encoder. Part 1. Designing a keyboard encoder. Part 2. Adding a digit select to a BCD encoder. Designing a keyboard encoder. Part 3. Audio feedback, a data bus, and a "clear" function. Tips on using the "Kaltek" SL-6 module to make a touch-sensitive switch that holds "on" for a predetermined amount of time. Has applications for computer keyboards. Using a TI-99 keyboard on a Sinclair ZX-81. From keypress to scan code. How IBM keyboards work and how they differ from one another. Includes a BASIC program to demonstrate the state of all shift keys, BIOS-level scan codes, and the high-level interpretation of those codes. Working with surplus keyboards. How they work and how to use them. Keyboard to microprocessor interfacing make easy. | |||||||||
Copyright © by Norman Lathrop Enterprises. All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means (electronic, mechanical, print photocopying, recording or otherwise) without the prior expressed permission of Norman Lathrop Enterprises, except as permitted by law. |
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