When I picked up a previous journal and found a copy of MSWLogo attached to the front, my first reaction was to say, “at last someone is taking LOGO seriously- this time I really must master it.” In the early days of computing in schools, LOGO was there but we were too busy batching up cards or checking coding sheets for ‘O’s in line numbers- then there was CPM to learn. Then came the wave of hobby computers.

Ten years ago, a proportion of our pupils had learnt some rudimentary coding in Basic, and the problem was to minimise their bad habits and introduce rigour and structure into their programming generally by teaching Pascal. Now we must teach programming (control?) skills from scratch as computers don’t arrive with a built in programming language. So has LOGO’s time come? Can it replace Pascal at ‘A’ level? Has it other uses?

A good spin doctor would describe LOGO as a dialect of Lisp (the artificial intelligence language) with a user friendly graphical front end. He would then explain that it has all the constructs needed to teach programming principles with the minimum of ‘syntax traps’. He would eulogise on the way that data structures can be taught, and the easy way that mathmos can tackle geometry and calculus. As MSWLogo is freeware- students can legally take a copy for their home machine.

Scheme and Logo are two dialects of Lisp, a language based on the processing of lists by using a composition of functions. In Logo everything is a procedure call. Procedural languages like Basic, C, and Pascal ultimately derive from Fortran, but Logo is a Lisp with Turtle graphics. Its creator Papert, studied with Piaget, and then worked at MIT.

There is no published standard. Logo has many dialects, some long dead and some extended. The version ACITT distributed was written by George Mills based on the work of Brian Harvey. Both Logos are free, so can be passed on to colleagues and students.

Brian Harvey wrote UCBLogo as a standard Logo that can be used on UNIX, Linux, DOS and Windows in DOS Mode. He is the acknowledged expert on Logo and has written the only serious textbook suitable for teachers of IT. Computer Science Logo Style. Three Volumes published by The MIT Press. I got a copy of Volume 1 for £24.40 from amazon.co.uk. There are details of all his books on Logo and Scheme on his website.

George Mills adapted UCB to take advantage of Windows dlls. It is not as pure as UCB but allows you to control the windows interface and some hardware features. There is provision for accessing dlls, midi sound and networking through TCP/IP can be invoked.

There are many Logo Tutorials on the Web. I started with Paul Dench

http://www.ecu.edu.au/pa/ecawa/sig/logo/paul_dench/turtle/index.html 

Jim Fuller is writing LOGO- working on control through the games port He has written a excellent formal tutorial.

Logo can be used at all levels. This tutorial will move too fast for some but addresses some of the problems of elementary robotics.

There is a wealth of logo ideas on the web, links can be found at:

The logo-l web newsgroup allows you to talk to all the people mentioned. To join send email to (majordomo@gsn.org). Include "subscribe logo-l" in body of the message, with no other text.

Logo is an interpreted language. It is not case dependent. It is written in lines.

Each line is made up of functions. There are two types

Functions can be primitives, or can be defined by the user.

Functions can take zero, one or more parameters.

There are three datatypes, the word, the list, the array.

A number is a special case of word.

There is no strong typing. The interpreter detects the datatype by context.

There are two important symbols:

The colon : - this means ‘the contents of’

This is an extremely useful symbol that keeps reminding students that a variable is really some ‘place’ in memory.

The quote ‘ - this means ‘the word is evaluated as itself’, or ‘its value after evaluation is the same as it was before’. This is important.

Discussing lists comes as a surprise to the Pascal programmer, who have managed quite well without them, however this opens many new possibilities. There seems to be few tutorials on this at any level- and none that can be plagiarised for school use. Arrays are also provided for the timid.

The standard Pascal controls are available, there is selection:

There are iteration commands:

Recursion is Logo’s preferred processing paradigm.

MSWLogo allows input from COM ports and LPT ports and also ‘hardware‘ ports. MSWLogo also supports a windows interface thus I/O is available through this GUI- and keyboard and mouse events can trigger interrupts.

Logo is slow, it is not suitable for processing vast amount of data- but surely this isn’t the point at ‘A’ level. Speed is not an issue anymore – sometimes it is educationally more useful if you can watch your program cranking through a problem. The visual output allows this. It assists the student’s understanding that the computer is working sequentially through the instructions.

Logo scores on graphics, and MSW allows you to use the Windows dll. The crucial point for ‘A’ level teaching in Pascal is that students must master ‘pointers’ before they can do any useful data structure theory. This excludes all except the most committed. In Logo, Lists, stacks and queues are trivial. Trees are more fun. All are recursive in nature.

Our students can be ‘reluctant programmers’. Many take no pride in computer programming and here the superior graphics helps to retain interest - Pascal cannot offer that.

If you are that committed to Pascal, UCBLogo and MSWLogo include a rudimentary Pascal interpreter written in Logo as one of its examples.

The Pascal programmer will be surprised by a series of list based control structures. The basic idea is that you have two lists

[ a list of commands ] [ many data items ]

Yes, there is turtle graphics. While ten years ago youngsters were excited by drawing a simple line on the screen, their aspirations have changed. The turtle graphics can be used to demonstrate visually the more complex ideas such as iteration and recursion. Its weakness is that it sends out the message that- “I used that when I was eight—do you think I am a baby?”

This is not a problem if

none of them have heard of LOGO before.

the alternative to simple line drawings is doing simple sums like the roots of a quadratic or the sum of a series which really bores them.

in a life of change familiarity offers security, and a chance to succeed.

The expert can generate series of graphics in LOGO. Save them as bitmaps then combine them as an animated gif for the killer web page.

With MSWLogo students can draw on the screen modal and modeless windows, buttons, comboboxes and slidebars. The buttons can be programmed to invoke code. Such a GUI is essential in today's youngster’s minds. It allows the less gifted the chance of producing a professional looking front end. It allows students to trigger events- in a way not offered in Pascal. It frees vast amounts of practical time for deeper study- and leads in to Form design in Access.

A tune is essentially a list of notes, and MSW has a sound command. It also can use MIDI files. More potential for gaining student’s interest. As you invoke the frequency and time as parameters there is opportunity to investigate the physics of music. You can get multiple PCs singing in harmony.

There is I/O to files, keyboard, to the COM and LPT ports, and from the games port. There are TCP/IP networking functions. This allows control possibilities. All I personally need is a set of ready made robots, and an operating system that allows me personal control of my machine’s I/O ports.

MSW Logo is rich, it is freeware and MSWLogo can deliver. What’s missing seems to be simple tutorials explaining these things. We need tutorials to extend the gifted, we need tutorials for the average and tutorials for special needs. We need tutorials on all aspects of the National curriculum. We need tutorials written in a way that we as Fortran/Pascal trained teachers can understand.