TweetFollow Us on Twitter

Modula-2 Compiler
Volume Number:1
Issue Number:6
Column Tag:Modula-2

Modula-2 Compiler by Modula Corporation

By Jörg Langowski

The ‘almost released’ beta version of the Modula-2 compiler by Modula Corporation has been around for some time now on several peoples’ desks, including mine. I feel it is time to report some of my experiences with this product.

Modula 2 is in some way the successor of Pascal, created by the same author, Niklaus Wirth from Zürich. Simple Modula 2 programs almost look like Pascal programs. Supposedly some of the inconveniences of Pascal have been straightened out in Modula 2, e.g., the rigid order in which declarations are made in Pascal has been relaxed. The most important new concept is that of modular compilation, which means that external (library) definitions can be ‘imported’ from separately compiled ‘modules’ at compile time and checked for correct passing of parameters, type mismatches etc

But I do not want to talk about language differences here. There has been a whole issue of BYTE dealing with Modula recently, and if you plan to use the Modula-2 compiler, you will have to get the standard reference book, ‘Programming in Modula-2’, by Niklaus Wirth, anyway.

The Modula-2 version that I received from Modula Corporation came on one Macintosh disk with a three-ring binder manual. The disk contains:

- The Modula-2 compiler and linker. Both are compiled Modula-2 programs, which means (for this system) that they are not native 68000 code, but rather M-code for a virtual machine, which has to be interpreted.

- The interpreter. The disk contains two versions, one of which is used to run the compiler and linker, the other one to run your compiled Modula-2 program.

- System libraries with precompiled modules for I/O, file handling, number conversion, string manipulation and - most important of all - toolbox access.

- a Decode utility to disassemble M-code. I found this of little use since I had no definition of the M-code instructions available.

- source code of a Graphics Demo and the Edit sample application that is also part of the IM manual.

- Edit, the same editor as in the Asm/Edit system.

- Rmaker, the (in)famous resource maker.

The manual gives a rather concise introduction on how to use the compiler and linker if you want to write a simple program or create a separately compiled module. Beside these instructions, it contains a listing of all the predefined modules that come with the system.

If you want to write a program that does just simple I/O and do not care about the user interface, you can use the standard GrafPort that the system comes up with when you start your application. Unfortunately, this is the full screen, not a nicely set up window like some other compilers have. You merely get a blank screen terminal emulation; if you want to use a window, you will have to define it through toolbox calls. You might want to take a look at the sample program in Listing 1 now.

This is a short matrix multiplication routine that initializes two matrices and determines the product matrix, then types out one element of the product as a check. You see that the actual calculation comprises about 25% of the total program, the rest is definitions and setting up of the window. Having read some of the other examples in MacTutor, you might not be surprised at that kind of overhead. The main parts of the program are:

- the IMPORT declarations, which get routines out of precompiled modules; note that not even simple I/O is defined by default, you have to import procedures for any kind of I/O that you want to do.

- some TYPE and VAR declarations - similar to Pascal. Integers (signed) and Cardinals (unsigned) are 16 bit by default. If you need a 32 bit integer, you have to use the LongCard TYPE, which is a record with the fields h and l, both CARDINAL. You have to assign them separately.

- toolbox PROCEDURE declarations. Unfortunately, there is no way to access a toolbox routine through its trap number directly; the routines are called (presumably) through numbers in another module, and the definitions that you have to use are given in the manual. Most of the toolbox routines (no - not all of them) are included. The definitions make as much sense to me as they make to you, but they seem to work.

- the actual program. You will notice there that the string format has to be converted from Modula (zero byte at the end) to Macintosh (character count in front) format.

The program is edited using the well-known Edit program, then passed as a file with the extension .MOD to the compiler. Compilation of this sample program takes 2 min 58 secs, add to that 25 secs to bring up the compiler. The reason for the system being so slow is of course that the compiler is written in M-code, too, and is interpreted. You quickly learn to examine your code very carefully for errors before you call up the compiler! One rather annoying feature of Modula-2 did not make things easier, either: Upper and lower case are distinguished, and it makes a difference whether you write WindowPtr or windowptr. Oh well Debugging the example, after it ‘almost’ ran, took me one hour, most of that time waiting for the compiler to finish.

The compiled program is then linked with the library modules (no linker errors here, since external references are already checked for completeness by the compiler) and you get a .LOD file, which, when double clicked, is executed by the Modula runtime interpreter.

Even though the compiler is slow, the generated code is rather fast. The example takes 21 seconds to execute. This is faster as you can ever do with the built-in 80-bit floating point package (judged from a similar program in Forth, which took over 40 seconds, most of that being floating point time). Modula-2 has its own 32-bit floating point package built in, which is precise enough for most applications. The Sieve runs 9 seconds per iteration, making a total of 90 secs for the standard 10 iterations. This, in turn, is slower than Forth (probably because the ratio M-code to built-in 68000 routines is higher in this case).

The timing results, in my opinion, make the Modula-2 system a very satisfactory choice for scientific and engineering applications. If Modula Corporation could come up with a compiler written in machine code, program development would be much more fun, too.

MODULE Matmul;

FROM InOut  IMPORT ReadCard, WriteCard, WriteString, WriteLn;
FROM Terminal  IMPORT ClearScreen;
FROM RealInOut   IMPORT ReadReal, GWriteReal;
FROM QuickDrawTypes  IMPORT Rect, GrafPtr, Str255, LongCard;
FROM ToolBoxTypes  IMPORT WindowPtr, WindowRecord;
FROM Strings   IMPORT StrModToMac;

CONST   CX = 355B;  QuickDrawModNum = 1; ToolBoxModNum = 2;


VAR   i,j,k : CARDINAL;
 sum,p,q : REAL;
 a : ARRAY [1..20] OF ARRAY [1..30] OF REAL;
 b : ARRAY [1..30] OF ARRAY [1..20] OF REAL;
 c : ARRAY [1..30] OF ARRAY [1..30] OF REAL;
 Wbounds : Rect;
 Wtitle : Str255;
 Wnew : WindowPtr;
 WrefCon, behind, OnHeap: LongCard;
PROCEDURE SetPort (port : WindowPtr); 
   CODE CX; QuickDrawModNum; 4 END SetPort;
PROCEDURE PortSize (width, height : INTEGER); 
   CODE CX; QuickDrawModNum; 8 END PortSize;
PROCEDURE TextFont (font : INTEGER); 
   CODE CX; QuickDrawModNum; 32 END TextFont;
PROCEDURE TextSize (size : INTEGER); 
   CODE CX; QuickDrawModNum; 35 END TextSize;
PROCEDURE NewWindow (wStorage : Ptr;  boundsRect : Rect;
                     title : Str255;  visible : BOOLEAN;
      theProc:INTEGER; behind : WindowPtr;
      goAwayFlag:BOOLEAN; refCon:LongCard) : WindowPtr; 
   CODE CX; ToolBoxModNum; 50 END NewWindow;

PROCEDURE DrawGrowIcon (theWindow : WindowPtr); 
   CODE CX; ToolBoxModNum; 64 END DrawGrowIcon;
PROCEDURE SelectWindow (theWindow : WindowPtr); 
   CODE CX; ToolBoxModNum; 56 END SelectWindow;

WITH WrefCon DO h := 0; l := 0 END;
WITH behind DO h := 65535; l := 65535 END;
WITH OnHeap DO h := 0; l := 0 END;
WITH Wbounds DO top := 50; left := 20; bottom := 300; right := 500 END;
StrModToMac (Wtitle, “Demo Window”); TextFont(0); TextSize(12);
Wnew := NewWindow(Ptr(OnHeap),Wbounds,Wtitle,TRUE,0,
SetPort(Wnew); SelectWindow(Wnew); DrawGrowIcon(Wnew);
PortSize(464,234); ClearScreen; TextFont(3); TextSize(9);
WriteString(“Initialization values for a: “); ReadReal(p);
WriteString(“, and b: “); ReadReal(q); WriteLn;

FOR i:= 1 TO 20 DO
 FOR j:= 1 TO 30 DO
 a[i][j] := p; b[j][i] := q 
WriteString (“Initialization done.”); WriteLn;

FOR i:= 1 TO 30 DO
 FOR j:= 1 TO 30 DO
 sum := 0.0;
 FOR k := 1 TO 20 DO sum:=sum + a[k][i]*b[j][k]  END;
 c[i][j] := sum

WriteString (“Multiplication completed.”); WriteLn;
WriteString (“ C[15,16] = “); GWriteReal (c[15][16],10);

END Matmul.


Community Search:
MacTech Search:

Software Updates via MacUpdate

MacPilot 8.0 - Enable over 1,200 hidden...
MacPilot gives you the power of UNIX and the simplicity of Macintosh, which means a phenomenal amount of untapped power in your hands! Use MacPilot to unlock over 1,200 features, and access them all... Read more
Typinator 6.7 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
Adobe Lightroom 6.2 - Import, develop, a...
Adobe Lightroom is available as part of Adobe Creative Cloud for as little as $9.99/month bundled with Photoshop CC as part of the photography package. Lightroom 6 is also available for purchase as a... Read more
ForeverSave 2.1.4 - Universal auto-save...
ForeverSave auto-saves all documents you're working on while simultaneously doing backup versioning in the background. Lost data can be quickly restored at any time. Losing data, caused by... Read more
VueScan 9.5.27 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
AirPort Utility 6.3.6 - Set up and manag...
Note: Most recent release available only within OS X 10.11 El Capitan update. Use AirPort Utility to set up and manage your Wi-Fi network and AirPort base stations, including AirPort Express, AirPort... Read more
Quicksilver 1.3.1 - Application launcher...
Quicksilver is a light, fast and free Mac application that gives you the power to control your Mac with keystrokes alone. Quicksilver allows you to find what you need quickly and easily, then act... Read more
Tidy Up (Five Users) 4.1.5 - Find duplic...
Tidy Up is a complete duplicate finder and disk-tidiness utility. With Tidy Up you can search for duplicate files and packages by the owner application, content, type, creator, extension, time... Read more
Mellel 3.4.3 - The word processor of cho...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
Skype - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more

Swords & Crossbones: An Epic Pirate...
Swords & Crossbones: An Epic Pirate Story 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Camel Up (Games)
Camel Up 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Martian: Bring Him Home (Games)
The Martian: Bring Him Home 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Based on the best selling novel and critically acclaimed film, THE MARTIAN tells the story of Astronaut Mark... | Read more »
This Week at 148Apps: September 21-30, 2...
Leap Into Fall With 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice, standing out above... | Read more »
Tweetbot 4 for Twitter (Social Networki...
Tweetbot 4 for Twitter 4.0 Device: iOS Universal Category: Social Networking Price: $4.99, Version: 4.0 (iTunes) Description: *** 50% off for a limited time. *** | Read more »
Mori (Games)
Mori 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Stop, rewind and unwind with Mori. Time is always running, take a moment to take control. Mori is an action puzzle game about infinitely... | Read more »
100 Years' War (Games)
100 Years' War 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Tower in the Sky (Games)
Tower in the Sky 0.0.60 Device: iOS Universal Category: Games Price: $1.99, Version: 0.0.60 (iTunes) Description: | Read more »
hocus. (Games)
hocus. 1.0.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0.0 (iTunes) Description: New, polished, mind-bending, minimal puzzle game with dozens of levels and extra-ordinary design Features:- Beautifully crafted... | Read more »
Mos Speedrun 2 (Games)
Mos Speedrun 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Mos is back, in her biggest and most exciting adventure ever! Wall-jump to victory through 30 mysterious, action packed levels... | Read more »

Price Scanner via

13-inch 2.5GHz MacBook Pro (refurbished) avai...
Apple has Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz MacBook Pros... Read more
27-inch 3.2GHz iMac on sale for $1689, save $...
Adorama has the 27″ 3.2GHz iMac on sale for $1689 including free shipping plus NY & NJ sales tax only. Their price is $110 off MSRP. Read more
12-inch Retina MacBooks on sale for up to $12...
B&H Photo has 12″ Retina MacBooks in stock today and on sale for up to $120 off MSRP. B&H will include free shipping, and there is NY sales tax only: - 12″ 1.1GHz Gray Retina MacBook: $1224 $... Read more
Tablets Shaping Up for Growth in 2016 – Strat...
Observing that Apple, Samsung, and Microsoft have refocused what tablet computers can do, market analysis firm Strategy Analytics believes there is immense opportunity for new and replacement sales... Read more
Apple Interbrand’s Number One Most Valuable G...
Apple and Google hold aced #1 and #2 spots respectively in Interbrand’s 2015 Best Global Brands Report, leading all tech brands that now comprise more than a third of the entire rankings value.... Read more
Apple offering refurbished 2015 13-inch Retin...
Apple is offering Certified Refurbished 2015 13″ Retina MacBook Pros for up to $270 (15%) off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: -... Read more
Apple refurbished 2015 MacBook Airs available...
Apple has Certified Refurbished 2015 11″ and 13″ MacBook Airs (the latest models), available for up to $180 off the cost of new models. An Apple one-year warranty is included with each MacBook, and... Read more
Adobe Photoshop Elements 14 Gets Haze Removal...
The latest iteration of Adobe’s powerful consumer image editing appliction Photoshop Elements 14 analyzes your photo and removes background haze, so your shot looks sharp all the way to the horizon... Read more
Apple refurbished 15-inch Retina MacBook Pros...
Apple has Certified Refurbished 2015 15″ Retina MacBook Pros available for up to $380 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2... Read more
21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $100 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1029.99 $70 off - 21″ 2.7GHz iMac: $1229 $70 off - 21″ 2.9GHz iMac: $... Read more

Jobs Board

Touch Validation Design (EE) - *Apple* Watc...
**Job Summary** Help launch next-generation Touch Technologies in Apple products. The Touch Technology team develops cutting-edge Touch solutions and technologies that Read more
WW Sales Strategy & Program Manager, *Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
*Apple* TV Product Design Internship (Spring...
…the mechanical design effort associated with creating world-class products with the Apple TV PD Group. Responsibilities will include working closely with manufacturing, Read more
Product Design Engineer - *Apple* Watch - A...
**Job Summary** Product Design Engineer - WATCH ( Apple Watch) Be an integral part of a small and visible team of world-class Mechanical Engineers making Apple 's Read more
Senior Software System App Engineer, *Apple*...
**Job Summary** The Apple Watch system application team is looking for great software engineers who are comfortable working across all levels of the software stack. From Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.