A type of programming in which the program is built from procedures and subroutines.

10 PRINT "Hello World"

This guide is written specifically for the Varvara implementation of the TinyBASIC compiler, but it should still give a general idea of how to use the language's primitives which are also found in most BASIC implementations.

Introduction

A BASIC program begins with line numbers, control-flow is done by jumping to absolute line numbers which point to compiled BASIC code data. 0 is not a valid line number.

15 LET A=0
20 PRINT "Hello BASIC"
25 LET A=A+1
30 IF A=10 GOTO 50
40 GOTO 20
50 END

Some BASIC compilers will do a light compilation where compiled lines hold a link to the following line in memory, as well as byte opcode for each statement.

40 09 00 0f 80 41 3d 30 00 40 1c 00 14 89 22 48
65 6c 6c 6f 20 42 41 53 49 43 22 00 40 27 00 19
80 41 3d 41 2b 31 00 40 39 00 1e 83 41 3d 31 30
20 47 4f 54 4f 20 35 30 00 40 41 00 28 81 32 30
00 40 47 00 32 8a 00 00 00 00 00 00 00 00 00 00

Expressions

Expressions can include numbers, variables and arithmetic operators. Numbers are decimal, but can be prefixed with $ for hexadecimal, there are no precedence rules. Valid expressions arithmetic operators are +-*/%, bitwise operators are &|, logic operators are <>=!. The smallest number is -32768, the largest number is 32767.

10 LET A=6+7
20 PRINT 52+$20*A
30 END

Variables

Variables are single character uppercased letters of the alphabet. Some variables have special properties, here is the complete list:

• H, reads the screen height, or sets the screen height.
• P, reads a value at address, or sets an address.
• R, reads a random number, or set the random number boundary.
• T, reads the time, in seconds.
• W, reads the screen width, or sets the screen width.

For example, if you wanted to do a program to roll a 6-sided dice using the R special variable.

10 LET R=6, D=R
20 PRINT "You rolled " D+1 "."
30 END

Interaction

The INPUT statement, will halt the execution and wait for an input. This can be used to store a value into a variable. For example, to capture the position of the mouse cursor:

10 PRINT "Touch the screen"
20 INPUT X, Y
30 PRINT "You touched at: " X ", " Y
50 PRINT "Press a button"
60 INPUT B
70 PRINT "You pressed: " B
80 END

To exit an INPUT loop, press the home, or select buttons.

Statements

RUN

REM This is a comment.

LIST 200

CLEAR

INPUT X, Y

LET A=123/2, B=$20%2

IF A>B-2 PRINT "A is greater."

PRINT "The result is: " A+B

GOTO 50+A>B

GOSUB 220

RETURN

END

Display

There is a handful of routines to draw graphics on the screen, to learn more about the limitations of the display, see the Varvara Screen Specs.

COLOR $50f2, $b0f9, $a0f8

CLS

DRAW 100, 320

MODE 04

SPRITE $1c1c, $087f, $0814, $2241

PICT image10x10.icn

Memory

Varvara BASIC is able to read and write source files, as well as export compatible roms.

SAVE example.bas

LOAD example.bas

MAKE game.rom

POKE A, B

• View source, Uxntal.
• Download ROM, 4kb.
• TinyBASIC User Manual
• MSX BASIC Commands
• BBC Micro VDU 23

Pascal is an imperative and procedural programming language designed for teaching students structured programming.

My main interest in the language is building little Macintosh applications such as graf3dscene, and exploring the THINK Pascal 4.0.2 environment. I have saved many example files in the Macintosh Cookbook repository.

THINK Pascal is a development system for the Macintosh, released by Think Technologies in 1986 as Lightspeed Pascal. Think Technologies was bought by Symantec, and the name was changed to Think Pascal. The last official update came 1992, and the product was officially discontinued in 1997.

Styleguide

A project should include the Runtime.lib library containing all standard Pascal routines such as writeln and sqrt. The interface.lib library contains the glue code for the all Macintosh Toolbox. Since routines from these two libraries are commonly used in almost all Pascal programs on the Macintosh, they are automatically included in the project file.

The standard adopted here concerns the naming of procedures, functions, and variables which both always start with an uppercase letter. Each new word within a name should also start with an uppercase letter. For example, GetNewWindow or SeekSpindle are fine function and procedure names; badPrcName isn't.

Variables always start with a lowercase letter. Use variable names like firstEmployee and currentTime. Global variables(variables accessible to your entire program) should start with a lowercase "g", like gCurrentWindow and gDone. The use of variable names such as glk and swpCk7 is discouraged.

program Example;

  {Comment}

  var
    name: STRING;

begin

  ShowText;
  name := 'alice';
  if (name = 'alice') then
    Writeln('The name is alice.')
  else if (a = 'bob') then
    Writeln('The name is bob.')
  else
    Writeln('The name is not alice nor bob.');

end.

Creating a procedure

A procedure definition in Pascal consists of a header, local declarations and a body of the procedure. The procedure header consists of the keyword procedure and a name given to the procedure. A procedure does not return anything.

program ExampleProcedure;

 procedure DrawLine (x1, y1, x2, y2: INTEGER);
 begin
  Moveto(x1, y1);
  Lineto(x2, y2);
 end;

begin

 ShowDrawing;
 DrawLine(20, 20, 100, 100);

end.

Creating a function

A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.

program ExampleFunction;

 function Add (a, b: INTEGER): INTEGER;
 begin
  add := a + b;
 end;

begin

 ShowText;
 Writeln('5+6=', Add(5, 6));

end.

Creating a type

An Object is a special kind of record that contains fields like a record; however, unlike records, objects contain procedures and functions as part of the object. These procedures and functions are held as pointers to the methods associated with the object's type.

program ExampleType;

 type
  Rectangle = object
    width, height: INTEGER;
   end;

 var
  r1: Rectangle;

begin

 ShowText;
 New(r1);
 r1.width := 12;
 r1.height := 34;
 Writeln('The rect is ', r1.width : 2, 'x', r1.height : 2);

end.

Creating a type with a method

program ExampleMethod;

 type
  Rectangle = object
    width, height: INTEGER;
    procedure setwidth (w: INTEGER);
   end;

 var
  r1: Rectangle;

 procedure Rectangle.setwidth (w: INTEGER);
 begin
  width := w;
 end;

begin

 ShowText;
 New(r1);
 r1.width := 12;
 r1.height := 34;
 Writeln('The rect was ', r1.width : 2, ' x ', r1.height : 2);
 r1.setWidth(56);
 Writeln('The rect is now ', r1.width : 2, ' x ', r1.height : 2);

end.

Creating a unit

To include the unit in another project, add uses ExampleUnit right after program Example, the procedures declared in the interface will become available.

unit ExampleUnit;

interface

 procedure DrawLine (x1, y1, x2, y2: INTEGER);

implementation

 procedure DrawLine (x1, y1, x2, y2: INTEGER);
 begin
  Moveto(x1, y1);
  Lineto(x2, y2);
 end;

end.

Console Program

program ExampleConsole;

 const
  message = ' Welcome to the world of Pascal ';

 type
  name = STRING;

 var
  firstname, surname: name;

begin

 ShowText;
 Writeln('Please enter your first name: ');
 Readln(firstname);

 Writeln('Please enter your surname: ');
 Readln(surname);

 Writeln;
 Writeln(message, ' ', firstname, ' ', surname);

end.

GUI Program

program ExampleGUI;

 var
  w: WindowPtr; {A window to draw in}
  r: Rect; {The bounding box of the window}

begin

 SetRect(r, 50, 50, 200, 100);
 w := NewWindow(nil, r, '', true, plainDBox, WindowPtr(-1), false, 0);
 SetPort(w);

 MoveTo(5, 20);
 DrawString('Hello world!');

 while not Button do
  begin
  end;

end.

Graphics Primitives

Graphical user interface design rests firmly on the foundation of OOP and illustrates its power and elegance.

Graphic Primitives Example

program Primitives;

  {Program to demonstrate Pascal point & line primitives.}

begin

  ShowDrawing; {Opens Drawing Window}

  {First draw three points by three different functions}

  PenSize(1, 1); {Sets pen size to 1 x 1 pixels}
  DrawLine(50, 50, 50, 50);
  WriteDraw(' Point at (50,50) using DrawLine');

  PenSize(2, 2);
  MoveTo(100, 75); {Absolute move}
  LineTo(100, 75);
  WriteDraw(' Point at (100,75) using LineTo');

  PenSize(3, 3);
  MoveTo(150, 100); {Absolute move}
  Line(0, 0);
  WriteDraw(' Point at (150,100) using Line');

  {Now Draw three lines by three different functions}

  MoveTo(150, 175); {Absolute move}
  WriteDraw('Line drawn with DrawLine');
  DrawLine(150, 125, 50, 225);

  PenSize(2, 2);
  Move(0, 25); {Relative move}
  LineTo(150, 250);
  WriteDraw('Line drawn by LineTo');

  Pensize(1, 1);
  Move(0, 25); {Relative move}
  Line(-100, 50);
  WriteDraw('Line drawn by Line');

end.

Graphics Primitives - Geometric Figures

Spiral Pattern

program EulerSpiral;

 const
  l = 4;
  a = 11;

 var
  wx, wy, wa: real;
  i: INTEGER;

 procedure DrawLineAngle;
  var
   t: REAL;
 begin
  MoveTo(round(wx), round(wy));
  t := wa * PI / 180;
  wx := wx + l * cos(t);
  wy := wy + l * sin(t);
  wa := wa + (i * a);
  LineTo(round(wx), round(wy));
 end;

begin

 wx := 100;
 wy := 300;
 i := 0;

 ShowDrawing;
 repeat
  DrawLineAngle;
  i := i + 1;
 until i > 20000;

end.

Button Events

Notes

A semi-colon is not required after the last statement of a block, adding one adds a "null statement" to the program, which is ignored by the compiler.

The programmer has the freedom to define other commonly used data types (e.g. byte, string, etc.) in terms of the predefined types using Pascal's type declaration facility, for example:

  type
  byte        = 0..255;
  signed_byte = -128..127;
  string      = packed array[1..255] of char;

If you are using decimal (real type) numbers, you can specify the number of decimal places to show with an additional colon:

Writeln(52.234567:1:3);

The 'whole number' part of the real number is displayed as is, no matter whether it exceeds the first width (in this case 1) or not, but the decimal part is truncated to the number of decimal places specified in the second width. The previous example will result in 52.234 being written.

Patterns

The available patterns are:

• black
• dkgray
• gray
• ltgray
• white

The following Think Pascal commands will be useful to you in writing interactive graphics programs on the Macintosh. They are listed by type:

Window Commands

Writing words on the screen:

Builtin Types

Builtin Procedures

String Procedures

Bit Operations

Syntax

• ^Shape is a type which is a pointer to the type Shape
• myShape^ takes a ^Shape and dereferences the pointer into a value
• @myShape takes a Shape and captures its address, giving you a ^Shape
• var myShape Shape is part of a argument declaration which means that the argument is passed as a reference, allowing the called procedure to modify it

Customization

If you are using THINK Pascal 4.0.2, as opposed to 4.5d4, the select all shortcut will be missing, and the default build shortcut will be ⌘G, instead of ⌘R. To change the menu shortcuts, open THINK Pascal with ResEdit, and add the missing shortcuts to the MENU resource. Remove the ⌘A shortcut from the Seach Again menu.

Going Further

The absolute best books on THINK Pascal are:

• Macintosh Pascal Programming Primer, Dave Mark & Cartwright Reed
• Programming in Macintosh and Think Pascal, Richard A. Rink & Vance B. Wisenbaker
• THINK Pascal: User Manual, Symantec. Inc
• Pascal Reference Manual, Apple Computer. Inc

• macintosh cookbook
• pascal central
• user manual
• Pascal and Simplicity

C is the native language of Unix. It has come to dominate systems programming in the computer industry.

Work on the first official C standard began in 1983. The major functional additions to the language were settled by the end of 1986, at which point it became common for programmers to distinguish between "K&R C" and ANSI C.

People use C because it feels faster. If you build a catapult that can hurl a bathtub with someone inside from London to New York, it will feel very fast both on take-off and landing, and probably during the ride, too, while a comfortable seat in business class on a transatlantic airliner would probably take less time but you would not feel the speed nearly as much. ~

One good reason to learn C, even if your programming needs are satisfied by a higher-level language, is that it can help you learn to think at hardware-architecture level. For notes specific to the Plan9's C compiler, see Plan9 C.

Compile

To convert source to an executable binary one uses a compiler. My compiler of choice is tcc, but more generally gcc is what most toolchains will use on Linux.

cc -Wall -lm -o main main.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int count = 10;

int
add_together(int x, int y)
{
	int result = x + y;
	return result;
}

typedef struct {
	int x;
	int y;
	int z;
} point;

void
print_point(point point)
{
	printf("the point is: (%d,%d,%d)\n",point.x,point.y,point.z);
}

int
main(int argc, char** argv)
{
	point p;
	p.x = 2;
	p.y = 3;
	p.z = 4;

	float length = sqrt(p.x * p.x + p.y * p.y);

	printf("float: %.6f\n", length);
	printf("int: %d\n", p.z);

	print_point(p);

	return 0;
}

Include

Generally, projects will include .h files which in turn will include their own .c files. The following form is used for system header files. It searches for a file named file in a standard list of system directories.

#include <file>

The following form is used for header files of your own program. It searches for a file named folder/file.h in the directory containing the current file.

#include "folder/file.h"

IO

One way to get input into a program or to display output from a program is to use standard input and standard output, respectively. The following two programs can be used with the unix pipe ./o | ./i

o.c

#include <stdio.h>

int
main()
{
	printf("(output hello)");
	return 0;
}

i.c

#include <stdio.h>

int
main()
{
	char line[256];
	if(fgets(line, 256, stdin) != NULL) {
		printf("(input: %s)\n", line);
	}
	return 0;
}

Threads

Threads are a way that a program can spawn concurrent operations that can then be delegated by the operating system to multiple processing cores.

cc threads.c -o threads && ./threads

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

#define NTHREADS 5

void
*myFun(void *x)
{
	int tid;
	tid = *((int *) x);
	printf("Hi from thread %d!\n", tid);
	return NULL;
}

int
main(int argc, char *argv[])
{
	pthread_t threads[NTHREADS];
	int thread_args[NTHREADS];
	int rc, i;

	/* spawn the threads */
	for (i=0; i<NTHREADS; ++i)
	{
		thread_args[i] = i;
		printf("spawning thread %d\n", i);
		rc = pthread_create(&threads[i], NULL, myFun, (void *) &thread_args[i]);
	}

	/* wait for threads to finish */
	for (i=0; i<NTHREADS; ++i) {
		rc = pthread_join(threads[i], NULL);
	}

	return 1;
}

SDL

cc demo.c -I/usr/local/include -L/usr/local/lib -lSDL2 -o demo

To compile the following example, place a graphic.bmp file in the same location as the c file, or remove the image block.

#include <SDL2/SDL.h>
#include <stdio.h>

int
error(char* msg, const char* err)
{
	printf("Error %s: %s\n", msg, err);
	return 1;
}

int
main()
{
	SDL_Window* window = NULL;
	SDL_Surface* surface = NULL;
	SDL_Surface* image = NULL;

	if(SDL_Init(SDL_INIT_VIDEO) < 0)
	return error("init", SDL_GetError());

	window = SDL_CreateWindow("Blank Window",
	SDL_WINDOWPOS_UNDEFINED,
	SDL_WINDOWPOS_UNDEFINED,
	640,
	480,
	SDL_WINDOW_SHOWN);

	if(window == NULL)
		return error("window", SDL_GetError());

	surface = SDL_GetWindowSurface(window);
	SDL_FillRect(surface, NULL,
	SDL_MapRGB(surface->format, 0x72, 0xDE, 0xC2));

	/* Display an image */
	image = SDL_LoadBMP("graphic.bmp");

	if(image == NULL)
		return error("image", SDL_GetError());

	SDL_BlitSurface(image, NULL, surface, NULL);

	/* Draw canvas */
	SDL_UpdateWindowSurface(window);
	SDL_Delay(2000);

	/* close */
	SDL_FreeSurface(surface);
	surface = NULL;
	SDL_DestroyWindow(window);
	window = NULL;
	SDL_Quit();

	return 0;
}

Misc

String padding: |Hello |

printf("|%-10s|", "Hello");

Macros

#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#define ABS(a) (((a) < 0) ? -(a) : (a))
#define CLAMP(x, low, high) (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))

• Sigrid on C
• Aiju on C

Smalltalk is an object-oriented language and environment, created for educational use.

In a Workspace, you can evaluate a selection and get the result with mouse2, and print it:

"Comment between double-quotes."
| x y sum |
x _ 4.
y _ 16rF.
sum _ x + y. 19

"Strings are within single-quotes"
|pokemon|
pokemon _ 'Drifloon' Drifloon

"To print the time"
Time now 6:49:44 pm

If you'd like to know more about a specific class:

Pen inspect.

Smalltalk uses the left-arrow notation to assign, which is inserted with _, the vertical-arrow is inserted with ^.

Conditional

| x |
x _ 15.
( x > 10)
	ifTrue: ['True' displayAt: 20@15]
	ifFalse: ['False' displayAt: 20@15].

Loops

| x y |
x _ 1. y _ 1.
20 timesRepeat: [x _ x + 8. y _ y + 16. 'hey' displayAt: x@y]

Drawing

Fill the screen

Display white
Display gray
Display black

Emulation

To change the resolution of the window of the Smalltalk-80 emulator:

DisplayScreen displayExtent: 800@480.

• Smalltalk Cheatsheet
• Smalltalk-80 Emulator
• Smalltalk-80: Bluebook, pdf

Hypertalk is the programming language used in the mac software Hypercard.

Hypertalk can be emulated easily using a Macintosh emulator, the default Hypercard canvas size is 512x342.

For most basic operations including mathematical computations, HyperTalk favored natural-language ordering of predicates over the ordering used in mathematical notation. For example, in HyperTalk's put assignment command, the variable was placed at the end of the statement:

put 5 * 4 into theResult

Go

The go command can be used in two ways. It can allow the user to go to any card in the stack that it is in or to any card of any other stack that is available.

visual effect dissolve
go to card id 3807

Put/Set

To change the text value, or textstyle of a field:

on mouseUp
  put random(100) into card field "target"
  set the textstyle of card field "Title" to italic
end mouseUp

Alternative, one can use the "type" command if the programmer wants to simulate someone typing something into a field. The type command will do very well here:

on mouseUp
  select before first line of card field "target"
  type "hello there"
end mouseUp

Show/Hide

The hide command can be used to hide any object. Some examples are: buttons, fields, and the menubar. The opposite of the hide command is the show command, and it can be used to make an object show up again.

-- a comment
onmouseUp 
  hide card field "title" 
  wait 5 seconds 
  show card field "title" 
endmouseUp

Choose

Each of the tools in the tool menu has a name that can be used with this command.

onmouseUp 
  choose spray can tool 
  set dragSpeed to 150 
  drag from 300,100 to 400, 200 
  wait 1 second 
  choose eraser tool 
  drag from 300,100 to 400, 200 
  choose browse tool 
endmouseUp

The available tools are:

• browse
• brush
• bucket
• button
• curve
• eraser
• field
• lasso
• line
• oval
• pencil
• rect[angle]
• reg[ular] poly[gon]
• round rect[angle]
• select
• spray
• text

Modal

Basic

on mouseUp
  ask "What is your name?"
  put it into response
  answer "You said " & response
end mouseUp

Logic with input

on mouseUp
  ask "What is your name?"
  put it into response
  if response is "blue" then 
    answer "correct."
  else
    answer "incorrect."
  end if
end mouseUp

Logic with choices

on mouseUp
  answer "Which color?" with "cyan" or "magenta" or "yellow"
  if it is "cyan" then 
    answer "You selected cyan."
  else
    answer "You did not select cyan."
  end if
end mouseUp

Play

The play command plays the specified sequence of notes with the specified sampled sounds. The tempo parameter specifies the number of quarter notes per minute; the default value is 120.

play "harpsichord" "c4 a3 f c4 a3 f c4 d c c c"

Globals

The global command is used to specify variables which will be available to other scripts within the stack or even in another stack. Unless variables are declared a global, they are considered by HyperTalk as local which means that they may only be used within a single script. If they are global, they may be carried to other scripts. Variables must be identified before they are used in order for them to become global.

-- allow access to globals
global var1, var2, ..
answer "hello " & var1 & "."

Summary

-- Let's put it altogether now
on mouseUp
  put random of 100 into n
  repeat 6
    ask "please input number(1-100)?"
    if it < n then
      answer "more than" && it
    else if it > n then
      answer "less than" && it
    else if it is n then
      answer "perfect!"
    exit mouseUp
    end if
  end repeat
  answer "You lose, myy answer is " && n 
end mouseUp

• tutorial guide
• tutorial video
• tips and tricks