TweetFollow Us on Twitter

About Modula-2
Volume Number:1
Issue Number:5
Column Tag:Modula-2

Modula-2

By John Bogan

Abstract: MODULA Corporation of Provo, Utah has shipped a $90.00 Beta site version of Modula-2 which runs reasonably well on a single disk 128K Macintosh. This paper attempts to make the case that Modula-2 deserves a thorough analysis to determine if it is the ideal standalone development language for serious commercial software on the Apple Macintosh. The conclusion of this paper is that Modula-2 will soon become the language of choice for farsighted software developers through the rest of the 1980’s and it is through the efforts of enlightened companies such as MODULA Corp. that this joyous result will come about.

A Short History of Modula-2

The history of Modula-2 is the history of its designer, Dr. Niklaus Wirth. We pick up the story in the late 1960’s when Dr. Wirth was a member of a large committee whose task was to design a successor to the language ALGOL-60, a highly popular language in Europe. ALGOL-60 is widely regarded as the inspiration for the discipline of Structured Programming which is the most significant breakthrough in software engineering in the past two decades. The result of this committee’s efforts was ALGOL-68, a kludge. No coherent design philosophy guided this effort resulting in a chaotic collection of features reminiscent of PL/I. In short, failure.

At this point Dr. Wirth abandoned the committee approach and decided to design his own language. Influenced by the structured programming theories of Dijkstra, Hoare and Dahl, Dr. Wirth set out to construct a language he could use to teach his own students the fundamentals of good programming. He began with some modest goals.

[“The development of the language Pascal is based on two principal aims. The first is to make available a language suitable to teach programming as a systematic discipline based on certain fundamental concepts clearly and naturally reflected by the language. The second is to develop implementations of this language which are both reliable and efficient on presently available computers.”] Pascal Report, page 1, 1974, Niklaus Wirth

The rest is history. As anyone who follows the computer industry well knows Pascal is one of the major influences on the software world today, particularly in the microcomputer world. To cite only one example the second largest manufacturer of personal computers in 1984 appears to have adopted Pascal as its standard design language. That company is, of course, Apple Computer, Inc. As I understand it most of the algorithms, data structures and techniques designed into the LISA and the Mac began life as Pascal programs.

But Pascal has significant flaws. Volumes have been written disparaging Pascal as a systems programming language and as a vehicle for writing applications of all stripes and colors. (Never mind that the language was never intended to do any of these things.) Further, and more disturbing, Pascal has been repeatly bastardized by its implementors with a wide variety of (incompatible) extensions. After a decade in the field there is no such thing as Standard Pascal any more than there is a tooth fairy. Nevertheless, many talented software people believe that even with its flaws Pascal is still the best practical general purpose language we have at our disposal. I believe this situation is about to change.

On with Wirth’s story. After largely washing his hands of Pascal Dr. Wirth turned his attention to multitasking and the problems of building large commercial programs using teams of programmers. As it happens Pascal is utterly unsuited for both of these activities. So Wirth designed himself a new, very simple language he called Modula. This language was never particularly practical it was more like a “hack” from one of the more gifted computer scientists around. However, it laid the groundwork for the concepts of seperate compilation, modularity and libraries.

In 1976 Dr. Wirth took a sabbatical from his mountain hideaway, Eidgenössische Technische Hochschule, Instut für Informatik, better known as ETH in Zürich, Switzerland and visited that fount of inspiration - Xerox PARC. As Mac enthusiasts we all know what that means. Personal workstations, high resolution bit maps, mice, windows, icons, Smalltalk etc. Less well known is the Xerox systems implementation language MESA. This language is a derivative of Pascal suitable for team implementation of low-level systems programs. The pieces were falling into place. Like many visitors to PARC Dr. Wirth came away with an inspiration.

Dr. Wirth was tired of the bitching and moaning surrounding Pascal.

[“If a language proves to be only marginally suitable for some application that was obviously not envisaged by its originator, we should muster the courage to build a new, truly adequate tool, instead of just grafting a fix onto the existing one.”] Byte, April 1983, pg. 386, Niklaus Wirth

Dr. Wirth’s inspiration was to build a new computer system from the ground up. A machine which would be programmed in one language from soup to nuts. From OS to text editor to graphics editor to who-knows-what, databases, spreadsheets, adventure games, what- ever. Recognizing that a one language machine would require the use of dangerous low-level facilities as well as the safety, convenience and productivity of the high level structured features he sifted through his encyclopedic knowledge of Pascal, Modula and MESA and in 1978 he defined his new language. To quote:

[“Modula [1], a small language ...featured a facility to partition programs into modules with explicitly specified interfaces. This was precisely the facility needed to allow the introduction of so-called low-level facilities in the high-level language, because it allowed you to encapsulate them and to constrain their danger- ousness to clearly delineated parts of a program. Hence, the choice for the new language was Pascal, augmented by the module and a few other facilites, and regularized by a more systematic syntax. Thus was born Modula-2.”] Byte, August 1984, pg. 146, Niklaus Wirth

Dr. Wirth had his ideal language. He then sat down with a couple of hardware types and some graduate students and built a bit-slice (AM2901) single-user high resolution graphic workstation with windows, mouse and multiple font editor with laser printer long before the Macintosh ever saw the light of day! He called his machine Lilith. The sole American distributor for the Lilith and the Modula-2 compiler which this machine is built around is MODULA Corporation of Provo, Ut., makers of Modula for Mac.

Modula Benchmark

The following program is an imple- mentation of the Sieve of Eratosthenes expressed in Modula Corporation’s version of Modula-2 for the Apple Macintosh 128K. The following results were obtained when this program was compiled and executed.

The source (Prime.MOD) = 1,617 bytes.

Compile time was -1:45

The M-code (Prime.REL) = 324 bytes.

Link time was -1:20

The execution module = 4,348 bytes.

Execution time was -1:11 or 71 seconds.

Modula-2 Compiler,Interpreter Ver. 1.0.

MODULE Prime;  (* Sieve of Eratos. *)
(* $R-  disable subrange and type conv *)
(* $T-  disable index checking *)
FROM InOut IMPORT WriteLn, WriteCard, WriteString;
FROM Terminal IMPORT ClearScreen;
CONST Size = 8190;
VAR i, prime, k, count, iter : CARDINAL;
      Flags : ARRAY[0..Size] OF BOOLEAN;
BEGIN
      ClearScreen;
      WriteLn; WriteString(“10 Iterations”);
      FOR iter := 1 TO 10 DO
           count := 0;
         FOR i := 0 TO Size DO Flags[i] :=                           
                        TRUE END;
           FOR i := 0 TO Size DO
                IF Flags[i] THEN
                     prime := i + i + 3;
                     k := i + prime;
                    WHILE k <= Size DO
                           Flags[k] := FALSE;
                           INC(k,prime)
                    END;
                  INC(count)
            END;
       END;
   END;
   WriteLn; WriteCard(count,6); WriteString(‘ Primes’)
END Prime.

Modula-2 Benchmarks

A Comparison between versions and machines

LEGEND

Code System Seconds

1. Lilith 4.24

2. Hamburg Vax 11/750 4.64

3. Logitech Eagle 6.90

4. ETH LSI-11 8.78

5. Logitech IBM PC 15.80

6. Volition Sage 66.14

7. Modula Macintosh 71.00

8. MRI Eagle 90.70

9. MRI IBM PC 203.60

10. Volition IBM PC 209.50

11. Volition Apple II 377.00

Source: “Seven Modula-2 Compilers Reviewed” by Terry L. Anderson Journal of Pascal, Ada & Modula-2 Vol.3 No.2

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

How to evolve Eevee in Pokemon GO
By now, almost everyone should be hip to how to evolve Pokemon in Pokemon GO (and if not, there's a guide for that). Just gather enough candy of the appropriate type, feed them all to the Pokemon, and evolution happens. It's a miracle that would... | Read more »
CSR Racing 2: Guide to all game modes
It might not seem like there are all that many ways to go fast in a straight line, but CSR Racing 2 begs to differ. [Read more] | Read more »
Bulb Boy (Games)
Bulb Boy 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Multi-award winning 2D point & click horror adventure about a boy with a glowing head. | Read more »
5 top free emoji keyboard apps
If we're not at peak emoji yet as a society, it feels like we definitely should be. The emoji concept has gone far beyond what anyone in Japan could have envisioned when the people there unleashed it on an unsuspecting world, but the West has... | Read more »
How to unlock more characters in Disney...
One of the big charms of Disney Emoji Blitz is seeing a wide variety of beloved Disney and Pixar characters transformed into smiling emojis. Even someone like the sneaky Randall from Monsters Inc., who probably never cracked a smile on film, is... | Read more »
Cubway (Games)
Cubway 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Cubway is a journey with an abstract story of lifecycle of rebirth, called Samsara. Guide the cube through the long way full of dangers... | Read more »
Colorcube (Games)
Colorcube 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Turn pieces and blend colours in this minimal yet visually stunning puzzler.Over 200 handcrafted and challenging levels. Features... | Read more »
Doodle God Griddlers (Games)
Doodle God Griddlers 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Crusader Kings: Chronicles (Games)
Crusader Kings: Chronicles 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Crusader Kings: Chronicles is an interactive text based game that puts you in the shoes of Guy de Rose as you make... | Read more »
Roads of Rome: New Generation (Games)
Roads of Rome: New Generation 1.0 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

Apple price trackers, updated continuously
Scan our Apple Price Trackers for the latest information on sales, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. We update the trackers continuously: - 15″... Read more
13-inch 2.5GHz MacBook Pro (Apple refurbished...
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
21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $120 off MSRP including free shipping plus NY sales tax only: - 21″ 3.1GHz iMac 4K: $1379 $120 off MSRP - 21″ 2.8GHz iMac: $1199.99 $100 off MSRP - 21″ 1... Read more
Charitybuzz Set to Auction Unique Apple-1 Com...
Offering an opportunity to own the computer that sparked a revolution, on Monday, July 25, leading online charity auction platform Charitybuzz will auction what is claimed to be the world’s most... Read more
MacBook Airs on sale for up to $150 off MSRP
Amazon has 11″ and 13″ MacBook Airs on sale for up to $150 off MSRP for a limited time. Shipping is free: - 13″ 1.6GHz/128GB MacBook Air (sku MMGF2LL/A): $899.99 $100 off MSRP - 13″ 1.6GHz/256GB... Read more
Apple refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
Apple refurbished 11-inch MacBook Airs availa...
Apple has Certified Refurbished 11″ MacBook Airs (the latest models), available for up to $170 off the cost of new models. An Apple one-year warranty is included with each MacBook, and shipping is... Read more
Apple iPad Pro Sales Far Outpacing Microsoft...
A report on Appleinsider notes that despite Microsoft Surface tablet PC sales growing by 9 percent year over year, revenues remained below $1 billion, and are down sequentially from the $1.1 billion... Read more
DEVONthink 2.9 Features Ultra-fast, Robust, A...
DEVONthink 2.9 allows users to keep databases synchronized using many means of transport. It transmits them between Macs on the local network or stores them in a syncable form on removable hard... Read more
12-inch WiFi Apple iPad Pros on sale for up t...
B&H Photo has 12″ WiFi iPad Pros on sale for up to $100 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $749 $50 off MSRP - 12″... Read more

Jobs Board

*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
*Apple* Professional Learning Specialist - A...
Job Summary The Apple Professional Learning Specialist is a full-time position for one year with Apple in the Phoenix, AZ area. This position requires a high Read more
*Apple* Picker - Apple Hill Orchard (United...
Apple Hill Orchard, Co. Rte. 21,Whitehall, NY 9/7/16-10/228/16. Pick fresh market or processing apples Productivity of 60 boxes and 80 boxes processing fruit per Read more
*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.