Radio Shack TRS-80 User manual

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A Special Note on Model III Computer Graphics •••
Be sure to use the GCLS command ("clear the Graphics
Screen") at TRSDOS READY when you first turn on your
computer. Otherwise, random graphics may appear on the
Screen.
Thank You
lIadlelllaeK
A DIVISION OF TANDY CORPORATION
FORT WORTH, TEXAS 78102·
8759223
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TERMS AND CONDITIONS OF SALE AND LICENSE OF RADIO SHACK COMPUTER EQUIPMENT AND SOFTWARE
PURCHASED FROM A RADIO SHACK COMPANY-OWNED COMPUTER CENTER, RETAIL STORE OR FROM A
RADIO SHACK FRANCHISEE OR DEALER AT ITS AUTHORIZED LOCATION
LIMITED WARRANTY
I. CUSTOMER OBLIGATIONS
A. CUSTOMER assumes full responsibility that this Radio Shack computer hardware purchased (the "Equipment"), and any copies of Radio
Shack software included with the Equipment or licensed separately (the "Software") meets the specifications, capacity, capabilities,
versatility, and other requirements of CUSTOMER
B. CUSTOMER assumes full responsibility for the condition and effectiveness of the operating environment in which the Equipment and Software
are to function, and for its installation
II. RADIO SHACK LIMITED WARRANTIES AND CONDITIONS OF SALE
A For a period of ninety (90) calendar days from the date of the Radio Shack sales document received upon purchase of the Equipment, RADIO
SHACK warrants to the original CUSTOMER that the Equipment and the medium upon which the Software is stored IS free from manufacturing
defects THIS WARRANTY IS ONLY APPLICABLE TO PURCHASES OF RADIO SHACK EQUIPMENT BY THE ORIGINAL CUSTOMER FROM
RADIO SHACK COMPANY-OWNED COMPUTER CENTERS, RETAIL STORES AND FROM RADIO SHACK FRANCHISEES AND DEALERS AT ITS
AUTHORIZED LOCATION The warranty is void if the Equipment's case or cabinet has been opened, or if the Equipment or Software has been
subjected to improper or abnormal use If a manufacturing defect is discovered dUring the stated warranty period, the defective Equipment
must be returned to a Radio Shack Computer Center, a Radio Shack retail store, participating Radio Shack franchisee or Radio Shack dealer
for repair, along with a copy of the sales document or lease agreement The original CUSTOMER'S sole and exclusive remedy In the event of
a defect Is limited to the correction of the defect by repair, replacement, or refund of the purchase price, at RADIO SHACK'S election and sole
expense RADIO SHACK has no obligation to replace or repair expendable items
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paragraph. Software Is licensed on an "AS IS" basis, without warranty The original CUSTOMER'S exclusive remedy, in the event of a
Software manufacturing defect, is its repair or replacement within thirty (30) calendar days of the date of the Radio Shack sales document
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participating Radio Shack franchisee or Radio Shack dealer along with the sales document
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III. LIMITATION OF LIABILITY
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OR ENTITY WITH RESPECT TO ANY LIABILITY, LOSS OR DAMAGE CAUSED OR ALLEGED TO BE CAUSED DIRECTLY OR INDIRECTLY BY
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INVOLVED.
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after the cause of action has accrued or more than four (4) years after the date of the Radio Shack sales document for the EqUipment or
Software, whichever first occurs
D. Some states do not allow the limitation or exclusion of incidental or consequential damages, so the above limitation(s) or exclusion(s) may
not apply to CUSTOMER.
IV. RADIO SHACK SOFTWARE LICENSE
RADIO SHACK grants to CUSTOMER a non-exclusive, paid-up license to use the RADIO SHACK Software on one computer, subject to the following
provisions:
A Except as otherwise provided in this Software License, applicable copyright laws shall apply to the Software.
B. Title to the medium on which the Software is recorded (cassette and/or diskette) or stored (ROM) is transferred to CUSTOMER, but not title to
the Software
C. CUSTOMER may use Software on one host computer and access that Software through one or more terminals if the Software permits this
function.
[) CUSTOMER shall not use. make, manufacture, or reproduce copies of Software except for use on one computer and as is specifically
provided in this Software License Customer is expressly prohibited from disassembling the Software.
E. CUSTOMER is permitted to make additional copies of the Software only for backup or archival purposes or If additional copies are required In
the operation of one computer with the Software, but only to the extent the Software allows a backup copy to be made. However, for
TRSDOS Software, CUSTOMER is permitted to make a limited number of additional copies for CUSTOMER'S own use
F. CUSTOMER may resell or distribute unmodified copies of the Software prOVided CUSTOMER has purchased one copy of the Software for each
one sold or distributed. The provisions of this Software License shall also be applicable to third parties receiving copies of the Software from
CUSTOMER. .
G. All copyright notices shall be retained on all copies of the Software.
V. APPLICABILITY OF WARRANTY
A The terms and conditions of this Warranty are applicable as between RADIO SHACK and CUSTOMER to either a sale of the Equipment and/or
Software License to CUSTOMER or to a transaction whereby RADIO SHACK sells or conveys such EqUipment to a third party for lease to
CUSTOMER
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Software and any manufacturer of the Equipment sold by RADIO SHACK
VI. STATE LAW RIGHTS
The warranties granted herein give the original CUSTOMER sp8CIfic legal rights, and the original CUSTOMER may have other rights which vary
from state to state.

computer Graphics Operation Manual
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TRS-8~· Computer Graphics Operation Manual Copyright
1982, All Rights Reserved, Tandy Corporation.
Reproduction or use without express written permission from
Tandy Corporation, of any portion of this manual is
prohibited. While reasonable efforts have been taken in the
preparation of this manual to assure its accuracy, Tandy
Corporation assumes no liability resulting from any errors
or omissions in this manual, or from the use of the
information obtained herein.
TRSDOS· Operating System Copyright 198~, 1981, Tandy
Corporation, All Rights Reserved.
BASIC Software Copyright 198~, Microsoft, Inc., All Rights
Reserved, Licensed to Tandy Corporation.
BASICG Software Copyright 1982, Microsoft, Inc., All
Rights Reserved, Licensed to Tandy Corporation.
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Computer Graphics Operation Manual
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Contents
To Our eus tamers. ...................................... .. 4
1/ Computer Graphics Overview •..•.••••..••••.••••.•.•••.• 7
Starting-Up .
Comm.ands •••••••••••••••••••••••• •' •••••••••••
2/ Graphics
BASICG BASIC (BASICG)
••...••••....••••••.•••••••••. 12
13
14
3/ Graphics utilities 59
4/ Graphics Subroutine Library (FORTRAN) •••••••••••••..• 91
5/ Programming the Graphics Board ••.••••...•..•.••••.•• 114
Appendix A/ BASICG/Utilities Reference Summary ••••••••• 117
Appendix B/ BASICG Error Messages ••..••••.•••••.•.••.•• 12~
Appendix C/ Subroutine Language Reference Summary •.•••. 125
Appendix 0/ Sample Programs
BAS leG. .................................•....... .. 127
Printing Graphics Displays ••.•..•...•••••••..•.••• 133
FORTRAN Sample Programs •..•••••...••••••••..••••.• 135
Appendix E/ Base Conversion Chart ••.••••.•.•.••.•••..•• 152
Appendix F/ Pixel Grid Reference •.••••••.•.•••.•.•••.•• 156
Appendix G/ Line Style Reference ..•.•••.•••••...•••..•. 162
Index. ............................................... .. 163
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Computer Graphics Operation Manual
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To Our Customers •••
The TRS-8~® Computer Graphics package revolutionizes your
Model III by letting you draw intricate displays from simple
program instructions. With the highly-defined Graphics
Screen, the list of practical applications is nearly
endless!
The TRS-8~ Computer Graphics package includes a:
Computer Graphics Diskette
Computer Graphics Operation Manual
However, before you can use this package, your Model III
must have 48K of RAM (Random Access Memory) and one disk
drive. Your computer must also be modified by a qualified
Radio Shack service technician. The only difference you'll
notice is a cable which protrudes from the bottom of the
Model III case. Do not attempt to disconnect this cable!
This cable is provided to allow you to attach peripheral
devices (such as a hard disk) to the I/O Bus Jack of the
Model III. The cable connector which is attached directly to
the I/O Bus Jack (see Point A in the figure below) must be
firmly attached for the Computer Graphics package to work.
A
Included on the Graphics diskette are:
TRSDOS 1.3
Disk BASIC
Graphics BASIC (BASICG)
Graphics Subroutine Library (GRPLIB)
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Computer Graphics Operation Manual
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Graphics Utilities
Sample Programs in BASICG and FORTRAN.
To print graphic displays, you can use any Radio Shack
printer that has graphic capabilities such as Line Printer
VII (26-1167), Line Printer VIII (26-1168), DMP-l~~
(26-1253), DMP-2~~ (26-1254), DMP-4~~ (26-1251), or DMP-5~~
(26-1252).
You can also utilize the Graphics Subroutine Library with
several languages, including, but not limited to FORTRAN
(26-22~~) •
About This Manual •••
For your convenience, we've divided this manual into five
sections plus appendixes:
Computer Graphics Overview
Graphics BASIC (BASICG) Language Description
Graphics utilities
FORTRAN Description
Programming the Graphics Board
Appendixes
This package contains two separate (but similar) methods for
Graphics programming:
Graphics BASIC (BASICG)
Graphics Subroutine Library
If you're familiar with Model III TRSDOS
ft
and BASIC, you
should have little trouble in adapting to Graphics BASIC.
If you want to review BASIC statements and syntax, see your
Model III Operation and BASIC Language Reference Manual
and Model III Disk System Owner's Manual. Then read
Chapters 1, 2 and 3, along with Appendixes A, B, E, and F of
this manual.
If it's Graphics applications in FORTRAN you're after, refer
to the TRS-8~ FORTRAN manual. Then read Chapters 1, 2, 3,
and 4 as well as Appendixes C, D, E, and F of this manual.
Note: This manual is written as a reference manual for the
TRS-8~ Computer Graphics package. It is not intended as a
teaching guide for graphics programming.
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computer Graphics
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Notational Conventions
Operation Manual
The following conventions are used to show syntax in this
manual:
CAPITALS
lowercase underline
<ENTER>
...
filespec
punctuation
delimiters
Any words or characters which
are uppercase must be typed in
exactly as they appear.
Fields shown in lowercase
underline are variable
information that you must
substitute a value for.
Any word or character contained
within brackets represents a
keyboard key to be pressed.
Ellipses indicate that a field
entry may be repeated.
A field shown as filespec
indicates a standard TRSDOS
file specification of the form:
filenamejext.password:d
Note that with TRSDOS 1.3, d
(Drive) can be any number
from ~-3.
Punctuation other than ellipses
must be entered as shown.
Commands must be separated from
their operands by one or more
blank spaces. Multiple
operands, where allowed, may be
separated from each other by a
comma, acomma followed by one
or more blanks, or by one or
more blanks. Blanks and commas
may
not appear within an
operand.
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computer Graphics operation Manual
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1/ Computer Graphics Overview
Graphics is the presentation of dimensional artwork. With
TRS-8~ Computer Graphics, the artwork is displayed on a
two-dimensional plane -- your computer screen. Like an
artist's easel or a teacher's blackboard, the screen is a
"drawing board" for your displays.
TRS-8~ Computer Graphics has two colors:
Black (OFF)
White (ON)
Graphics programming is different from other types of
programming because your ultimate result is a pictorial
display (bar graph, pie chart, etc.) rather than textual
display "(sum, equation, etc.). This is an important
distinction. After working with graphics for a while, you'll
find yourself thinking "visually" as you write programs.
In computer-generated graphics, displays can include tables,
charts, graphs, illustrations and other types of artwork.
Once they're created, you can "paint" displays with a
variety of styles and shapes, or even simulate animation.
The Computer Graphics program uses a "high-resolution"
screen. The more addressable points or dots (called
"pixels") on a computer's screen, the higher the resolution.
A lower resolution screen has fewer addressable pixels.
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Computer Graphics Operation Manual
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PIXEL- .......
Lower resolution Higher resolution
Figure 1. Resolution
Since the TRS-8~ has high-resolution -- 64~ pixels on the
X-axis (~ to 639) and 24~ pixels on the Y-axis (~ to 239)
you can draw displays that have excellent clarity and
detail.
How TRS-8~ Computer Graphics Works
The concept of graphics is fairly simple. Each point on the
screen can be turned ON (white) or OFF (black).
When you clear the Graphics Screen, all graphic points are
turned OFF.
Therefore, by setting various combinations of the pixels
(usually with a single command) either ON or OFF, you can
generate lines, circles, geometric figures, pictures, etc.
The Graphics Subroutine Library, which is part of the
Computer Graphics package, contains subroutines which
provide the same capabilities, as well as similar names and
parameters, as the commands and functions in Graphics BASIC.
The main difference between the Subroutine Library and
BASICG is the manner in which coordinates are specified
(e.g., BASICG coordinates are specified as arguments for
each command while the Subroutine Library specifies
coordinates with a separate subroutine call). Another
difference concerns the names of a few routines (e.g., LINE
vs. LINEB vs. LINEBF, etc.). All of these differences will
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