[editor : Carl T. Helmers Jr.] [publisher : Virginia Peschke, Manfred Peschke] #Magazine

#Abstract

One result of the BYTE Audio Cassette Symposium last November was a provisional standard for audio recording, essentially identical to that described by Don Lancaster in issue No. 1 of BYTE last September. In this issue, Don presents an updated design and describes how to Build The Bit Boffer. Then, to show that there's more than one way to spin a tape, Harold Mauch gives some details of a second system compatible with the standard in his article Digital Data on Cassette Recorders.

Jack Hemenway uses Don Lancaster's Bit Boffer desi gn to wire up The COMPLEAT Tape Cassette Interface using an ACIA attached to his 6800. But completeness requires more than hardware, so Jack provides software of six subroutines for the control and transfer of data with this interface.

Creating programs can be done with a variety of tools. The best way is to use an interactive terminal with "mass storage available and a good high level language. But, when you move up country or have other reasons to be away from convenient access to monster machines, at first things have to be done the hard way using a new home brew machine. This makes the techniques of Assembling Programs by Hand invaluable for your bag of tricks.

In the previous issue, information on joysticks and slide pots was presented. In this issue, John Schulein supplies a short note on another Pot Position Digitizing Idea.

It is one thing to tell how to do something, but why it works is often a separate topic. William A Manly provides answers to a lot of the "whys" of magnetic mass storage in h is article on the physics of Magnetic Recording for Computers.

One of the newer microprocessor designs is the General Instrument CP1600. In his Microprocessor Update, Bob Baker summarizes the technical information about this chip design.

Last month, Prof W Douglas Maurer described some salient points about processing algebraic expressions. In this issue, he continues the discussion with Part 2 of Processing Algebraic Expressions. This includes a simplified explanation of what it means to generate code as in a compiler.

Peek inside a video display terminal with Don Walters' quick summary of What's in a Video Display Terminal.

And to round out the theme of magnetic recording technology, the cover shows a typical Philips style audio cartridge.

[author : Carl Helmers] #Edito

Extract : «  No computer system is complete without mass storage of some form. Mass storage is a nice subject to talk about, but just what is it and how can it be implemented? What are the factors which affect the ability of your computer to dump and recover data in machine readable form? What are the technologies available at prices low enough to be affordable by many individuals? How is a tape interface controlled?

Much of this issue of BYTE is devoted to articles on the problem of mass storage and practical but inexpensive systems. [...]  »

TABLE OF CONTENTS

[theme : Systems] [author : Hemenway] #Interface #Storage #Electronic #Listing #Assembly

Extract : «  Mass storage is one of the most important functions in the small computer system design. Mass storage can typically be used as the medium of a text editor, as the input and output of a full fledged language translator program, and as a means of saving working and debugged software you've created. One of the least expensive ways to accomplish mass storage is the audio cassette storage method. [...]  »

[theme : Hardware] [author : Lancaster] #Interface #Storage #Electronic

Extract : «  The BIT BOFFER is a low cost way to store and retrieve digital data onto and off an ordinary cassette tape, using stock audio tape recorders. You can also use it to exchange data, recording on one machine and playing back on a second. The BIT BOFFER is totally software independent, meaning that it can be used with or without a microprocessor system. All that's needed to control it is a simple "data ready" command to send something on to the recorder; you also get a "data available" command when the recorder produces an output. The BIT BOFFER can be connected to any serial data port of a microprocessor or other system. [...]  »

[theme : Hardware] [author : Mauch] #Interface #Storage #Electronic

Extract : «  Nearly everyone has a portable cassette recorder. If you don't have one, chances are your kid does ("Hey, Mom, Dad stole my tape recorder!"). These recorders range from the under $20 "bare bones" variety to multi centibuck units with nearly every feature imaginable. Fortunately it should be possible to use nearly any cassette recorder available if it is clean and in good working condition. Pawnshops and similar outlets are good sources of used cassette recorders. Used recorders are often quite dirty and may need repair. Take along a couple of test cassettes when you go shopping and check out the units' operation before buying. [...]  »

[theme : Software] [author : Helmers] #Listing #Assembly #Programming

Extract : «  When you build your one of a kind computer from an assemblage of parts and components liberally mixed with wire wrap wire, your ultimate goal is to program the machine for experimental and practical purposes. One of the most important software elements of the complete home brew computer system is a set of programs used to help you develop further programs. This type of software programming aid is quite familiar to those of us who have a "large computer" background. The thought of a bare bones machine with no real software development tools is horrifying, to say the least. How is it possible to create this needed software generating software for the home brew computer? [...]  »

[theme : Hardware] [author : Schulein] #Electronic #Digitization

Extract : «  A scheme to convert the position of a potentiometer arm into a digital value, using a cheap commonly available timer IC (NE555) and a few bytes of program in an 8008 or 8080 microprocessor, is shown in figure 1. The software is organized as a subroutine and uses the flags and the A and B registers. The NE555 is triggered by the OUT TRIGGER instruction and then the program monitors the output pin of the NE555 in a loop that increments the B register. When the NE555 times out, the program exits from the subroutine and the B register contains a digital representation of the pot position. [...]  »

[theme : Hardware] [author : Manly] #Interface #Storage #HowItWorks #Glossary

Extract : «  Why Magnetic Recording?

Anyone seriously involved with computers, whether he likes it or not, will also be seriously involved with magnetic recording. After one begins working with computers, it doesn't take very long to discover the shocking fact that memory for a computer is going to cost a lot more than the computer itself. A computer requires lots of memory, and professional or amateur, the computer user wants to minimize the cost of his computer setup. A look at figure 1 will immediately tell you why magnetic recording is so important to computer memories: Nothing can come anywhere near it for low cost per unit of stored information. Figure 1 also shows why magnetic recording cannot be used for all types of computer memories: It is the slowest of the memories, which means that it is employed mostly for long term, low usage storage (usually called bulk storage). [...]  »

[theme : Hardware] [author : Baker] #Review #Microprocessor

Extract : «  The CP1600 is a complete, 16 bit, single chip, MOS-LSI microprocessor available directly from General Instrument for $99 in single quantity. It utilizes third generation minicomputer architecture as shown in the block diagram in figure 1. Figure 2 shows the actual pin assignments of the 40 pin dual-in-line package. Standard operating voltages required are: +12 V, +5 V, and —3 V DC. The simple bus structure is TTL compatible and allows direct memory access (DMA) capabilities for high speed data transfers. [...]  »

[theme : Software] [author : Maurer] #Algorithm #Programming

Extract : «  In an article which appeared last month, we showed how the small system user can process algebraic expressions by using the Bauer-Samelson algorithm, developed by F L Bauer and K Samelson at the Technische Hochschule in Munich, Germany. The Bauer-Samelson algorithm has many variations, depending on the type of algebraic expression processing we wish to do. The most interesting of these have to do with the process of compiling. [...]  »

[theme : Systems] [author : Walters] #ComputerTerminal #Display #HowItWorks

Extract : «  Let's look at the video display terminal as a black box which is connected to a computer system (somehow) as depicted in figure 1. Since the computer system has already been explained (at the block diagram level) in BYTE ("The State of the Art" by Carl Helmers, November 1975, page 6), we will concentrate on what smaller black boxes make up a video display terminal. [...]  »

#Association

#Book

Extract : «  The Missing Man by Katherine Mac Lean, published by Berkeley Publishing, 1975, 220 pp, $6.95 hardback. [...]

Digital Design With Standard MSI & LSI by Thomas R. Blakslee, John Wiley & Sons, 1975, 357 pp, $19.95 hardback. [...]  »