CHAPTER 4 
USING MiniMINC WITH SERIAL
ASCII EQUIPMENT

This chapter gives a general description of how MiniMINC com-
municates with serial ASCII equipment and describes how to
use LISSJU.BAS, a demonstration program that creates Lissaj-
ous figures on an interactive plotter.

SERIAL ASCII EQUIPMENT
MiniMINC can communicate with instruments that transmit 
characters according to EIA standard RS—232C. This standard 
sets the protocol for serial transfer by which most terminals (in-
cluding the MiniMINC terminal) and some other instruments,
such as interactive plotters and analytical balances, transmit
and receive ASCII characters (see Appendix A in Book 2: MINC
Programming Fundamentals for a table of ASCII codes). Serial
transfer is a method of data transmission in which the compo-
nents of a data word are transmitted one after another (serially)
along a single pair of lines from a sending to a receiving device.

MIniMINC’s SLU PORTS
You connect devices to MiniMINC via the six SLU (Serial Line 
Unit) ports located on the back panel of the chassis (see Figure 
16).


MR-S-190-79
Figure 16. Back of the MiniMINC Chassis 

37

INTRODUCTION TO MiniMINC

The ports and their uses are:

MODEM 
for sending and receiving data with
the MINC NFT option via modems
(devices used in long distance trans-
mission of digital data), acoustic
couplers, or direct cable

PRINTER 
for sending data to a printing de-
vice (printer)

CONSOLE 
for communication with the
MiniMINC terminal
TERMINAL #3
TERMINAL #2
TERMINAL #1
for communication with most ter-
minals, printers, and other serial
ASCII equipment conforming to
EIA standard RS—232C

The MODEM, PRINTER, and CONSOLE ports perform only
their designated functions; the TERMINAL #3, TERMINAL
#2, and TERMINAL #1 ports are identical, general-purpose
ports that function with a variety of devices. Chapter 2 of the
MiniMINC Supplement provides information and illustrations
regarding the connection and use of serial ASCII equipment
with MiniMINC.

SERIAL ASCII ROUTINES 
Communication between MiniMINC and a device depends on
programs that include a set of special MiniMINC routines.
These routines (SET-SERIAL, CIN, and COUT) transfer char-
acters between MiniMINC and a connected serial ASCII device
and determine the speed at which the characters travel, how
they are represented, and the method to be used for checking
their-integrity. Chapter 2 of the MiniMINC Supplement de-
scribes the routines in detail. 

THE SERIAL ASCII DEMONSTRATION PROGRAM
LISSJU, a serial ASCII program, creates Lissajous figures on a
Tektronix 4662 interactive digital plotter.

Description of LISSJU 
When the program starts, you supply five values that determine
what kind of Lissajous figure LISSJU will create. The program
computes the graph coordinates for your Lissajous figure and
then chains to PLOT, a program that controls the plotter. PLOT
causes the plotter to draw a border, the labels, and then the Lis-
sajous figure.

38 

USING MiniMINC WITH SERIAL ASCII EQUIPMENT

Lissajous figures are frequency patterns commonly generated
on an oscilloscope by connecting a source of known frequencies
to one set of deflection plates and an unknown frequency to the
other set. A recognizable pattern results when one frequency is a
harmonic or integral multiple of the other, thus revealing the
unknown frequency. _

The following line in LISSJ U contains the parametric equations
used in computing the graph coordinates (REM is the RE-
MARK statement. It distinguishes a comment from the execut-
able portion of a program. See Book 3: MINC Programming Ref-
erence for a description):

X=SIN(X1*M*I+X2)\Y=SIN(Y1*M*I+Y2)\REM THE LISSAIOUS EQUATIONS

where:

X1 is the horizontal multiplier
Y1 is the vertical multiplier
X2 is the horizontal phase in radians
Y2 is the vertical phase in radians
M is 2PI divided by one less than the number of
points N
I is an integer that progresses from 1 to N

The ratio of X1 to Y1 determines the actual shape of the Lissaj—
ous figure. These multipliers are the frequencies of the X and Y
sine waves that combine together to form the Lissajous figure.

The phase shift resulting from the combined effects of X2 and
Y2 causes the figure to "rotate" so that if you created a series of
Lissajous drawings with identical multipliers (X1 and Y1), each
drawing would be a different view of the same figure. Figures
17 through 19 show the rotation of a Lissajous figure with a 1/3
frequency ratio.

PLOT’s Serial ASCII Routines
The SET_SERIAL routine in the PLOT program sets the at- 
tributes of the serial line connecting MiniMINC with the plotter. 
This routine adjusts the serial line each time you run the pro-
grams to create a Lissajous figure. Chapter 2 of the MiniMINC
Supplement explains the SET-SERIAL routine in detail.
The COUT serial ASCII routines in PLOT signal the plotter
when to print text and when to plot points. They then direct the 

39

INTRODUCTION TO MiniMINC


40

USING MiniMINC WITH SERIAL ASCII EQUIPMENT

plotter’s pen to the proper coordinates, creating the final figure.
Chapter 2 of the M iniMIN C Supplement also describes this rou-
tine and its use.

The Procedure
Power up MiniMINC and the plotter (you can find the plotter’s 
switch settings documented inside the PLOT and LISSJU pro-
grams). Next, insert the demonstration diskette into
MiniMINC’s drive unit 0 and engage the system. Then type:

RUN LISSIU [RET]

LISSJ U responds:

LISSJU creates Lissajous figures on an interactive digital
plotter (see Chap. 4, Introduction to MiniMINC).

Note that LISSJU produces a figure of almost any
frequency ratio and phase shift. However, to produce
high-quality drawings, please confine your responses to the
following ranges:

1. Ratio between horz/vert multipliers not to exceed 40:1
2. Phases of O to 360
3. No. of points no greater than 295

HORIZONTAL MULTIPLIER?

For the purpose of this demonstration, type the following values:

HORIZONTAL MULTIPLIER? 5 [RET]

VERTICAL MULTIPLIER? 6 [RET]

HORIZONTAL PHASE ANGLE IN DEGREES? 18 [RET]

VERTICAL PHASE ANGLE IN DEGREES? 18 [RET]

NO. OF POINTS TO USE (0-295)? 250 [RET]

LISSJU then verifies your answers with the following
messages:

LISSAIOUS FIGURE WITH 5/6 RATIO MADE WITH 250 POINTS

MULTIPLE OF 5 - PHASE OF 18 DEG

MULTIPLE OF 6 - PHASE OF 18 DEG

Approximately 50 to 60 seconds will pass before the plotter be- 

41

INTRODUCTION TO MiniMINC

gins to draw. If you entered the values recommended for this ex-
ample, the plotter will produce a figure like the one in Figure 20.


MR-S-193-79
A Figure 20. Lissajous Figure — Plotter Sample

You can examine the LISSJU and PLOT programs with the
OLD and LIST commands. Type:

OLD LISSJU [RET] or OLD PLOT [RET]

When MiniMINC responds with READK type:

LIST  [RET]

If you have a printer connected to the MiniMINC, type:
COPY LISSJU LP: [RET] or COPY PLOT LP: [RET]

42

CHAPTER 5
A MiniMINC PROGRAMMING
PRIMER

This chapter describes how programs are used in MiniMINC
and suggests a method you can use for developing programs.
Book 2: MIN C Programming Fundamentals discusses the
MINC BASIC language and how to program in it.

PROGRAMS - A DESCRIPTION
A program is a set of computer instructions or symbolic state- 
ments combined to perform some task. 

MiniMINC has two types of programs: system programs that
make up the programming system and user programs (also
known as application programs) that perform the special tasks
required by the user. There are programs of both types supplied
with MiniMINC — system programs and some user programs
that demonstrate MiniMINC’s capabilities.

MiniMINC system programs are machine language programs
that are immediately intelligible to the computer without the in-
tervention of a translating facility (the high—level MINC BASIC
language requires interpretation before execution). System pro-
grams control and direct the computer’s activities.

MiniMINC user programs are series of MINC BASIC state-
ments combined to perform tasks required by users. Such tasks
include data processing, graphic displays, and serial ASCII
data transfers.

CREATING USER PROGRAMS
Writing a program to run on MiniMINC requires a program- 
ming method and knowledge of the MINC BASIC language and 
program structure. Book 2: MINC Programming Fundamentals 

43

INTRODUCTION TO MiniMINC

explains MINC BASIC and this chapter explains a program-
ming method.

There are probably as many ways to write a program as there
are programmers, but not every method results in an efficient
and effective program. This chapter describes one method that
works. Note that the following pages describe steps to take be-
fore finally writing the program in the MINC BASIC language.

Defining a Program's Objective
First determine what you want the program to do.
Suppose you want a program that arranges names in a list.
There are some basic questions you must answer before you can
write the program. For instance:

• How should the names be ordered (alphabetically, ran-
domly, order of importance)?

• In what form should the names appear (full name, last
name only, last name and first initial)?

• How many names will the list contain (fixed or varia-
ble number)?

• How will the computer receive the names (typed at the
terminal or from a file on diskette)?

• In what form should the results appear (on the ter-
minal screen, in a file, or on paper from a printer)?

The answers to questions like these help to clarify the program’s
objective.

A definition of the program’s objective can help you to judge the
program’s feasibility in terms of available time and resources.
For instance, your potential program may require a printer
when your system lacks one or you may not have the time neces-
sary to type long lists of names should they be required. What-
ever the limiting factor or factors (computer memory size, lim-
ited time, unavailable equipment, or insufficient data), you can
adjust your program’s objective accordingly. Thus a compre-
hensive definition at the outset of your project can save you time
and frustration later on while you’re programming.

Pretend, for the sake of illustration, that you need a program to
sort a list of names. Your requirements are for a program that
will:

44

A MiniMINC PROGRAMMING PRIMER

• accept up to 1000 names from the terminal

• use names in the form of last name and first initial

• sort names alphabetically

• display the names in correct order on the terminal
screen

This program already exists as the demonstration program
ALPHA. The remainder of this chapter traces ALPHA’s devel-
opment up to the final programming effort.

Outlining a Solution
The next step in building a program is to establish your pro- 
gramming strategy.

Create an outline for your program by describing the program’s
method of operation in general terms. Your outline should in-
clude every process required by your program to achieve its ob-
jective. The processes should account for the input of data, data
processing, and the output of data. When creating the outline,
list the processes according to their sequence in the program.

For example, you can outline ALPHA in the following way:

1. Input names

2. Reorder names

3. Output reordered names .

This outline represents everything the program must do. Step 1
is data entry, Step 2 is data processing, and Step 3 is the result.

Outlining a solution increases the likelihood that you will de-
velop an effective program. If you are satisfied that the outline
contains all the processes required by the program’s objective,
then proceed to the next step. The ability to define a process will
develop as you learn the MINC BASIC program structure
described in Book 2: MIN C Programming Fimdameritalsr

Constructing an Algorithm
An algorithm is a fixed series of vvell—defined procedures that 
solves a problem in a finite amount of time. It is the essence of a 
program.

An algorithm summary is the written representation of an algo-
rithm. The summary often takes the form of brief English sen-
tences or statements that succinctly describe each procedure 

45

INTRODUCTION TO MiniMINC

within the algorithm. These sentences or statements appear in
the summary in the same order as the procedures they describe.

Consider the outline for ALPHA. The first process, input-
ting the names, uses an algorithm described in the following
summary:

1. Create array for storing unordered names

2. Receive name from terminal

3. If no more names, then go to Step 6

4. Store name in unordered array

5. Go to Step 2 

6. Stop

The procedures are performed in numerical order. However,
some procedures override this order by directing control to a
specific procedure as in steps 3 and 5. Step 3 switches control to
Step 6 when you are finished typing names. The switching pro-
cedure in Step 3 reflects a MIN C BASIC programming tech-
nique called a conditional branch. Step 5 always passes control
to Step 2. This switching procedure reflects an uncondition-
al branch. You should always take care to limit the number of
branches of either kind. Algorithm summaries (and programs)
can become confusing unless most of the activity is performed in
simple numerical order.

You may wonder why there are so many steps in this algorithm
summary This is because each procedure corresponds to a
MINC BASIC statement or set of statements that you will learn
about in Book 2.

For the moment, concentrate on the form of the algorithm sum-
mary Mentally test the algorithm. The more you remember of
its pattern, the better you’ll understand the discussions on pro-
gram structure in Book 2. This is true because a program is an
algorithm translated into action by the use of a programming
language.

The following algorithm summaries show how ALPHA reor-
ders and then outputs names.

46 

A MiniMINC PROGRAMMING PRIMER

REORDER NAMES

1. Create array to store ordered names

2. Take next name from unordered array

3. Compare name with next name in unordered array I

4. Take name with lowest alphabetical position, switching po-
sition of names if necessary

5. If name compared with last element of unordered array,
then go to Step 7

6. Go to Step 3

7. Insert name in first open position of ordered array

8. If every name in unordered array tested for alphabetical
order, then go to Step 10

9. Go to Step 2

10. Stop

OUTPUT ORDERED NAMES

1. Display next name in ordered array 

2. If end of ordered array, then go to Step 4

3. Go to Step 1

4. Stop

NOTE

The word "next" in the algorithm summaries can also
mean "first." This practice reflects how the BASIC
language handles arrays.

Examine these algorithm summaries carefully. Notice how ex-
plicit they are. This exactness is required because programs di-
rect the computer’s operation, and computers perform only as
directed. If you write a program based on an ambiguous algo-
rithm, you must compensate for the ambiguity while program- 


47

INTRODUCTION TO MiniMINC

ming. However, because programming involves much more de-
tail than constructing algorithms, allowing ambiguity into your
algorithm summary greatly increases your work load.

The three algorithm summaries given in this chapter should be
combined into one summary to represent the entire ALPHA
program. The resulting algorithm summary for ALPHA is:

1. Create array for storing unordered names

2. Receive name from terminal

3. If no more names, then go to Step 6

4. Store name in unordered array 

5. Go to Step 2

6. Create array to store ordered names

7. Take next name from unordered array

8. Compare name with next name in unordered array

9. Take name with lowest alphabetical position, switching po-
sition of names if necessary

10. If name compared with last element of unordered array,
then go to Step 12

11. Go to Step 8

12. Insert name in first open position of ordered array

13. If every name in unordered array tested for alphabetical
order, then go to Step 15

14. Go to Step 7

15. Display next name in ordered array

16. If end of ordered array, then go to Step 18

17. Go to Step 15

18. Stop

48 

A MiniMINC PROGRAMMING PRIMER

Notice that the "stops" formerly at the end of each process algo-
rithm are missing. They were needed because a loop (a repeat-
ing sequence of events) inside each process terminated itself and
the process by sending control to a stop. Now that the processes
are combined, control passes to the next process instead of ter-
minating at a stop. The stop at Step 18 remains to terminate the A
ALPHA algorithm.

The algorithm described for ALPHA is only one of several algo-
rithms capable of the same function. In fact, there is almost al-
ways more than one solution to any given programming prob-
lem. Keeping this in mind, you should evaluate your program
objectives carefully in order to construct the most efficient and
effective algorithms possible. A useful technique that can im-
prove your understanding of a process, as well as the quality of
the final algorithm, is to develop several algorithms for the same
program.

Testing an Algorithm
After constructing an algorithm, and in its early stages of devel- 
opment, you should test the algorithm for integrity of design or
soundness.

To be sound, an algorithm must solve a problem in a finite
amount of time with a fixed series of well-defined processes.
Every process required to solve the problem must therefore be
included within the algorithm and occur in proper sequence.
There must also be a point in time when all the processes are fin-
ished and the problem is solved.

A method for appraising an algorithm’s design integrity is to
mentally trace the path of several data items through the algo-
rithm, one item at a time. You can detect flaws with this method
that you would probably overlook in a general inspection.

Try this method on ALPHA’s algorithm. Perform each step in
the algorithm separately and in the indicated order. For now,
and whenever you test an algorithm in this manner, suspend
youryintuition and perform each step exactly as described.

Using a piece of paper as the unordered array, write down a
name each time you encounter Step 4, until you’ve entered four
or five names (any names will do). When you’ve entered all the
names, Step 3 directs you to Step 6. Continue with the algorithm
until you reach the stop in Step 18. Use additional paper to rep-
resent the ordered array and ALPHA’s output.

This simple test method should work for all programming algo- 

49

INTRODUCTION TO MiniMINC

rithms. Proceed to the next stage in program development, im-
plementing the algorithm, when you are convinced of the
algorithm’s soundness.

Implementing an Algorithm
An implemented algorithm is a program. The writing of a pro-
gram requires knowledge of a programming language and pro-
gram structure.

You should next read Book 2: MINC Programming Fundamen-
tals. This book explains what you need to know to begin pro-
gramming in MINC BASIC. The other MiniMINC manuals
(Book 3: MIN C Programming Reference, Book 4: MIN C Graphic
Programming, and the MiniMIN C Supplement) describe the
MINC BASIC commands, statements, and routines.

SUMMARY 
The MiniMINC system uses two types of programs: system and
user programs. System programs control and direct the
computer’s operations and thus form part of the MiniMINC sys-
tem. User programs are created by MiniMINC users to perform
tasks with the system. The system programs are machine lan-
guage programs and the user programs are high-level language
programs.

There are many ways to create user programs. This manual
demonstrates one of them. The steps involved are:

Define a program’s objective

Outline a solution

Construct an algorithm

Test the algorithm

Implement the algorithm

Book 2: MIN C Programming Fundamentals explains how to im-
plement an algorithm with the MINC BASIC language.


50

CHAPTER 6
DIRECTIONS FOR READING THE
MiniMINC MANUALS

EXPERIENCED PROGRAMMERS
If you are an experienced programmer in a language other than 
BASIC, we recommend that you follow the reading order sug— 
gested below for novice users.

If you are familiar with BASIC, but not MINC BASIC, you
should at least skim Books 2 and 3 for new commands and the
MiniMINC approach to standard commands.

NOVICES
Book 2: MINC Programming Fundamentals continues your edu- 
cation in MiniMINC programming, but concentrates on more
practical matters such as file creation and editing. It teaches
MINC BASIC fundamentals in a thorough, uncomplicated
manner using examples. You should find Book 2 and Chapter 5
of this manual sufficient preparation for programming on your
own.

You will probably need to review sections of Book 2 before you
fully understand MINC BASIC as a "language." Review and
practice are the keys to a functional understanding of MINC
BASIC or any other programming language. Only by gaining
experience will you achieve programming proficiency.

You should find Book 3: MINC Programming Reference useful
once you start programming. Book 3 and the MiniMINC Sup-
plement together describe every command, statement, function,
and routine in MINC BASIC.

Book 4: MINC Graphic Programming teaches the concepts un-  
derlying graphics and conducts you through some demonstra-  
tions. Its second half serves as a reference manual for graphic 

51

INTRODUCTION TO MiniMINC

routines once you begin graphic programming. We recommend
that you read it thoroughly beforehand.

Reserve the MiniMINC Supplement for last. This book contains
technical information for connecting MiniMINC to printers
and other devices, testing your equipment, and correcting prob-
lems that may arise. The Supplement also describes new fea-
tures that Books 1 through 4 don’t point out.

52