John St. Clair
2007-05-13 16:34:56 UTC
The message below is being cross-posted from the LogoForum. Please
reply here at comp.lang.logo and it will be crossposted back to the
LogoForum. The original author of this message is "Daniel Ajoy"
<***@gmail.nospam.com>.
I had this web page in my personal archive
[1] Classic Computer Magazine Archive
CREATIVE COMPUTING VOL. 10, NO. 12 / DECEMBER 1984 / PAGE 94
__________________________________________________________
[2]Daily Free Software Picks
A comparison of Logos: today's turtle is no slowpoke. (evaluation)
Richard Roth.
Turtles and mice are the "in" animals in the personal computer field
this year. As in nature, microcomputer mice have both supporters and
detractors, but almost everyone agrees that turtles are beneficial
beasts--on the screen as well as in the stream.
The main role that computerized turtles play these days is in the Logo
language, a language that has journeyed from the Artificial
Intelligence Lab at MIT where it was developed to the classrooms of
the world in hust a few years.
The main difference between Logo and other languages is that Logo is
intended to encourage learning by using the power of the computer,
rather than being designed for writing programs. The child learns what
a computer can do while working with familiar concepts from the world
around him. The language demonstrates concepts by ignoring them and
allowing the user to cause results immediately and understand them
later.
The original Logo work done at MIT has evolved, through use, into an
effective core language. Two main categories of enhancements, sprites
and advanced programming features, distinguish the various current
versions of the language from one another.
Since Papert's work was financed with NSF grant money, early versions
can be licensed through MIT. Most of the advanced versions of Logo
have been developed by Papert's associates at Logo Computer Systems,
Inc. (LCSI). Let's have a look at some of the enhancements that have
been added by this and other companies. Sprites and Demons
A sprite is very much like one of Stephen Speilberg's Gremlins. It is
something to which you give the initial impetus and which then
continues on its own. Fortunately, you can interrupt it from time to
time to give it new instructions.
Sprites add to Logo the ability to set events in action and wathc the
results. The child can define a rule or a series of rules and then sit
back and watch them at work.
A demon is an "event" or action that is triggered by a timer, an input
device (such as a joystick or paddle), or the collision of two
sprites. An example is a procedure in which two trucks travel back and
forth across the screen. A cat runs on a path perpendicular to the
path of the trucks, and when either truck collides with the cat (don't
worry, the cat never seems the worse for the wear), it meows loudly.
The trucks and cat are sprites, and the cat's voice is a demon
triggered by the collision of the sprites.
Logos that offer sprites are all based on a specific graphic chip, the
TI 9918/9928 which was developed by Texas Instruments just for Logos.
Therefore, sprites are found only in Logos for the Apple with an
add-on sprite board and the Coleco Adam and TI 99/4A which have sprite
hardware built in. there is no reason that a sprite Logo could not be
developed for a high powered machine like the IBM PC or PCjr, but as
yet no one has done it. Advanced Programming Features
The advanced programming features offered by some versions of Logo can
bring the language into the realm of Artificial Intelligence
programming previously dominated by Lisp. As a replacement for Lisp,
Logo has some advantages because of its clearer syntax and better
support environment.
In addition to the standard list processing features of Logo, Digital
Research's Dr. Logo and LCSI's Logo offer good string and variable
manipulation capabilities. So far, however, Logo has been used mainly
in the lower grades and the real power of these capabilities has been
lost on most of the teachers using it. While the physcial connection
of turtles and sprites is clear, the list processing power of Logo
seems to be obscure to many users. Features to Compare
The basic feature of all Logos is the turtle. In addition, some Logos
offer multiple turtles, either as static objects or as sprites. All
Logos allow you to change the color of the turtle and its track, and
some even allow you to change the shape of the critter.
The programming features of all Logos are based on a procedure called
the TO, as in TO SQUARE--to draw a square. The basic language features
are loops (REPEAT) and tests (IF). As a Logo becomes more advanced,
variables are added using MAKE and then lists with such operators as
FIRST, BUTFIRST (all but first), LAST, and BUTLAST. And since lists
can contain both words and sublists, the concept of a sentence--a
simple list of only words--can be introduced.
The real power of any language is demonstrated in the way it interacts
with the machine on which it is running. For Logo, this interaction
starts with the color screen and extends to the keyboard and other
input devices. The ability to save and print procedures is a
requirement for any serious use. Unfortunately, most Logos lack the
ability to print the graphic screen.
The other important feature to consider in assessing the
sophistication of a Logo is disk operation. Complexity of disk
function ranges from simple text "stream" files to full file system
access. The Reviews
In trying to order the following collection of product reviews, I
settled on the price of the hardware system as an impartial order that
would be of at least casual interest to most users. The result is a
mixture of descriptions of Logos of different levels and ages, and
should be read accordingly. TRS-80 Color Logo
As the lowest priced system for which Logo is available, the 16K
TRS-80 Color Computer 2, is of more than passing interest to many
schools. The cartridge version of Logo for this machine is the basis
for a full education-oriented teaching system which includes student,
teacher, and parent manuals and a full set of transparencies for use
in the classroom.
The package concentrates on the turtle graphics functions of Logo with
a couple of interesting twists. Because it is intended for a very
small machine and beginning educational use, the package provides a
good set of turtle manipulation functions. Going are beyond the single
turtle provided by most of its competitors, this Logo offers the
sprite-like ability to define up to 255 turtles, each of which can
have a different shape and be controlled independently.
An additional feature, which is clearly aimed at very young users, is
the dooble mode. In this mode, the child can control the turtle with
single keystrokes. The resulting picture can be captured as a Logo
procedure and then edited as the child's familiarity with the language
increases.
Commands in Color Computer Logo are limited to those that control the
motion of the turtle complemented by SEND, MAIL, NEAR, and ME to
control multiple turtles. The Shape command sets the shape of the
turtle.
Users who have peripherals will be glad to note that this Logo reads
the paddles and allows procedures (but not graphics) to be printed.
The language as implemented by Tandy has a few minor oddities, the
most significant of which is the use of parentheses instead of square
brackets in statement lists. This change was made in deference to the
Color Computer keyboard, which has no brackets, but it detracts
somewhat from the ability to generalize Logo concepts from one system
to another.
The language is well complemented with manuals for the student and the
teacher. Particularly notable are the Color Logo Guide for Teachers,
Book One, and The color Logo Guide for Parents, Book One. Both books
are co-authored by computer education pioneer Bob Albrecht and offer
excellent step-by-step pictorial lessons. Disk Version
The only difference between the cartridge and disk versions of Color
Computer Logo is that using the disk is far easier than loading and
storing procedures from and to audio tape.
The only drawback to the disk version is that the disk operating
system occupies a great deal of memory, so the language cannot be used
on a 16K system. the addition of the extended memory option and disk
drive changes the nature of the system, removing it from the realm of
truly low cost computing.
A boon to users of the larger 64K Color Computer II would be an
advanced version of Logo that has been hinted at by Tandy. Some Tandy
watchers speculate that the new version will work with the company's
recently released color printers-- a delightful thought. Teacher's
Package
The Teacher's Package offered by Tandy may be a cost-effective
solution for schools that want the convenience of disk access for
multiple computers. The Package is actually a system which uses the
Radio Shack Network 2 Controller to connect up to 16 16K Color
Computers to one disk drive.
Also included in the package are a teacher's manual, overhead
transparencies, and individual student handbooks.
This is a very impressive package, and if he Logo it supported were
just a bit more sophisticated, I believe it would capture the hearts
of teachers on all levels. As it is, it does an excellent job of
supporting the first level Logo class, but falls short for more
advanced users. Coleco Adam
Smart Logo for the Coleco Adam is one of the latest versions of Logo
from LCSI and benefits from all this venerable organization has
learned about building and packaging Logo systems. It comes on an Adam
tape cartridge and begins with a very complete interactive tutorial.
The tape also includes demo programs and tools for advanced users.
Smart Logo benefits from an accident of fate which makes it one of the
best Logos I have seen. The basic ColecoVision game machine upon which
the Adam is based, uses the TI 9918 graphics chip described above, and
just as this chip gives ColecoVision games a great deal of extra
pizzazz, so it adds a whole new dimension to the Logo language,
including sprites and demons.
Smart Logo is a full implementation of Logo with all of the functions
described in the introductory section of this article. Its only faults
can be attributed to the fact that the Adam is a 64K Z80 system that
suffers from the basic memory and speed liminations of an 8-bit
processor, liminations that will escape the notice of all but the most
ardent and advanced programmer.
For graphics and sound, this Logo offers support of the Adam game
controllers and a set of functions to control the four-channel sound
generator built in to the computer. Procedures and graphics can be
saved, but only procedures can be printed on the character printer.
The Coleco system uses tape cartridges for storage, and although it
does take two minutes to get the system up and running, the matter
turns out to be of little concern because the tape is accessed only
rarely. My only real complaint about the tape system is that the
command SAVE can not be used to replace an old file nor to create a
backup. In my test situation, this meant that children had to be
taught about backup filenames and deletion of old files, a process
that lead to lost files and some tears before it was understood.
The disk drive, which Coleco has promised for the fourth quarter of
1984, will support all the functions now available with the tape drive
at considerably improved speed.
The manual is a small format loose-leaf binder. It includes a tutorial
section and a reference section that provides detailed examples and a
good index. At the back of the manual are a reference card and an
errata sheet. Apple II+, IIe, and IIc
Even though the original work on Logo for microcomputers was done on
the TI 99/4A, the various Apple versions of the language have been
driving force behind the widespread acceptance of Logo in the
educational community. Logo was first implemented on the Apple through
an NSF grant at MIT, and MIT has since licensed the software and
manual to two suppliers, Terrapin and Krell. Both companies offer
basically the same Logo with vastly different levels of documentation
and support for their customers.
In addition, the version of Logo developed by LCSI for the Apple and
Atari computers has been adopted as the official Apple version and has
been enhanced, resulting in two more versions--one with an add-on
hardware board for sprites. MIT Logo
MIT Logo is a combination of turtle graphics functions and list
processing functions. The turtle uses an Apple shape table and so may
be changed by more sophisticated users.
Other features of the Apple that lend themselves to Logo are the Apple
graphics screen which offers six colors and a nice work area for the
turtle, and the disk drive which can be used to save procedures and
pictures, either of which can be printed in black and white.
The MIT version of Logo has a a full set of statements for turtle
graphics and procedure writing. There are also list and sentence
processing operations and the ability to add assembler primitives.
The screen editor works smoothly except for the problem of square
brackets for enclosing lists on older computers. Like the
ColorComputer, the Apple II and II+ lack brackets on the keyboard, and
to get them on the screen, you must press Shift-N and Shift-M, which
can be a bit awkward. The problem does not exist on the Apple IIe and
IIc, both of which have square brackets on the keyboard.
You can interact with MIT Logo procedures by using primitives for
either the keyboard or the game paddles.
Utilities includes with MIT Logo can aid the beginning programmer with
examples and provide the advanced programmer with an assembler that
saves 6502 machine code directly. The exact set of utilities varies
with the supplier; however, both include the assembler and sample
programs like Rocket, the game of Animal, a single key doodle mode
called Instant, the music interface to the Apple speaker, and a
general file utility. Krell Logo
Krell Logo is the original MIT Logo with some interesting but not very
significant additions. Included in the package is a wall chart that is
useful for experienced programmers but can be confusing for the
beginner.
The introduction of the language is handled in a disk called Alice in
LogoLand. The package is a good introduction, but has some awkward
features that make it less effective. The documentation itself is a
reprint of the original MIT technical manual and is a bit of a
hodge-podge.
In sum, the Krell package is reminiscent of the state of the art in
1981 when it was first released. The intention is good, but it comes
off poorly. The main advantage of this package is the backup copy of
the boot disk that comes with the original. Terrapin Logo
The Terrapin version of MIT Logo is a considerably more advanced
product than the Krell version. Terrapin has enhanced both the
usefulness and the friendliness of MIT Logo with a complete user
tutorial and two unusual peripherals for its language.
The first peripheral, the Terrapin robot turtle, is a mechanical
turtle that can be controlled using Logo commands just as the graphic
turtle can. It is fascinating to experiment with a three-dimensional
object under program control. Unfortunately, the $300 price tag tends
to keep the turtle out of the hands of most children.
The second peripheral offered in conjunction with Terrapin Logo is the
Micro Mint Sprite Board, the first attempt to make sprite graphics
available on the Apple. While the attempt is less than completely
successful, it does demonstrate what can be done with sprites on the
Apple. The main problem with the system is that it requires two
monitors--one for the video from the Apple and one for the video from
the sprite graphics processor. For the hobbyist or experimenter, the
product is challenging and fun to use; for the classroom, it is just
doesn't make it. Apple Logos from LCSI Apple Logo--The Original
The LCSI Logo that became the official Logo for the Apple is a
smoother language than either of the two versions of MIT Logo. The
package comes with a reference manual and a tutorial that are as good
as or better than the best parts of both the Terrapin and Krell
versions.
The LCSI language lacks some of the more interesting features of the
MIT version, including the ability to save pictures to disk, and call
assembler routines. Also lacking is the utility disk. These are all
features that are of use primarily to the advanced user.
On the other hand, LCSI has added some features that will be welcomed
by users who plan to write lessons in the language. These include
cleaner syntax for logical operators like AND/OR, packages and buried
packages, property lists, and error THROWing and CATCHing. Apple Logo
II
Logo is not a static or stagnant language, and LCSI continues to
enhance and improve it. The latest official Apple Logo offers a
revised set of manuals and a set of file operations (called
primitives) that allow it to be used with ProDOS on a 128K Apple IIe
or IIc. The only problem I observed was that a system this large
begins to tax the speed of the Apple disk drives when loading
initially or using the disk heavily. With a hard disk, of course, this
problem vanishes.
The new, improved Apple Logo from LCSI is excellent for beginners and
more than adequate for advanced AI applications.
A second improved version of Logo from LCSI comes with a sprite board
that can be used with the Apple II+ and IIe. Since the language itself
was designed to take advantage of the sprite board, all graphics and
text appear on the same video display.
The package includes extensive examples that demonstrate how to
control sprites and redefine the shapes of existing characters. The
only function not provided by the TI 9918 chip on the add-on board is
the use of demons. There are, however, similar functions that test for
collisions between turtles and/or sprites. IBM PC
As with every other category of software, the market presence of IBM
has inspired a large assortment of Logo packages for that machine. The
graphics capability of hte PC ensures that all versions score well in
that area. Much to my surprise, however, none of the available Logos
for the IBM offers sprites, even though the 8088 processor can support
them through software. Instead, the PC Logos have concentrated on
advanced programming features. IBM Logo
As the official IBM Logo, this LCSI package is matched only by its
sister product for the Apple. It features both a complete manual with
reference and tutorial sections and the most complete language
available.
As mentioned above, this Logo lacks sprites, but its full file system
access makes it the implementation of choice for advanced users in
both AI and teaching situations. For beginning users, the only
drawback--and it is a small one--is the depth of hte supplied example
material.
The language is all there; it is hard to say more without being
repetitious. All the turtle graphics commands are supported as are the
programming and list processing features. Graphics are supported by
the standard IBM hardware without low level access, and hackers will
appreciate an assembler call facility that resembles Basic.
The only feature that advanced programmers will miss is subdirectory
support, a lack attributable to the fact that IBM Logo is not yet
available in a DOS 2.0 version.
Despite the fact that it is an official IBM product, I had difficulty
obtaining a copy of IBM Logo. So if your local store denies all
knowledge of the product, persevere; it does exist and is well worth
the effort once you find it. PC Logo
PC Logo from Harvard Associates is a good version of a turtle graphics
Logo with all the extended features needed for advanced programming.
The package makes good use of the PC function keys and is well adapted
for the IBM machine.
Extra primitives allow for very simple and complete control over the
PC screen and other hardware devices. Again, hackers will appreciate
direct access to PC DOS and the BIOS ROM as well as many other low
level features. The only thing missing is an assembler call.
At the same time, PC Logo can be used with ease by a child or
relatively inexperienced grade school teacher.
The manual has an esy to read tutorial and a complete reference
section packaged in an IBM-sized binder. A good set of examples is
included on the disk, and a reference card completes the package.
Harvard Associates offers a complete Logo package to schools, which
includes volume licensing plan and price incentive.
Not part of the package, but a peripheral that schools should consider
buying is the Turtle Tot, a robot turtle that accepts its commands
from PC Logo. Also available for the Apple, the device is a favorite
among children of all ages. Waterloo Logo
The University of Waterloo, long known for such favorites of computer
science majors as the WatFor and WatFive fast Fortran compilers, has
lately been working on a set of microcomputer tools, including a
networking system and a language set to complement it. With this
background, it is easy to understand the role of Waterloo Logo, an
implementation that would probably not survive on its own.
The package is well done, but terse. It includes a reference card and
a manual "writeen for people who already have programming experience
using a high level language."
The language as implemented here is a good basic Logo system which is
well adapted for the IBM PC, but as a competitive product it just
cannot hold its own. LadyBug Logo
One of the most impressive Logos for the PC is impressive not because
of its fancy packing or its great manual or even its fantastic
features. It has no packaging its manual is only fair; and its
features are complete, but not fantastic. No, the package is
impressive because of its price; it is free.
LadyBug Logo is freeware, and unfortunately, while people seem willing
to pay $35 for a copy of PC-Talk, PC-Write, or PC-File, they are
reluctant to pay for an educational package. Dave Smith, the author of
LadyBug Logo, requested that users make a donation toward further
development work. Sadly, he reported that barely 1% of the 500 people
to whom he has sent copies have sent him any money. I promised him I
would challenge the readers of Creative Computing to prove that
educational freeware can pay. Copies are available from the Young
People's Logo Association and on many PC bulletin boards.
As for the language, itself, it is a full turtle graphics language
with disk procedure storage and a good set of examples. The 84-page
manual is on disk and includes a good index.
Special features of this version of Logo are a PLAY function for
music, access to joysticks, and a full screen procedure editor.
Running under DOS 2.0, the language allows graphics screens to be
printed and just fits on the PCjr.
For advanced users, there is a good debugging mode, but the package is
show--about half as fast as most of the other PC Logos--even though it
is written in compiled Basic. Logo for Other Computers
In addition to the products discussed above, there are also Logos for
the TI 99/4A, Commodore 64, and Atari computers. Computers for which
versions of Logo will soon be released include the DEC Professional,
Macintosh, Sanyo MB550, and TI Professional. Logo for the Future
I predict that we will continue to see enhanced and improved versions
of Logo. Most will come from LCSI, which has established itself as the
main supplier of the language and has used its relationship with
Seymour Papert to enhance the language and encourage educational
programs to use it.
I have even seen some evidence that disk versions of Logo are being
aimed at a wider audience than just the parents, teachers, and
children who make up the education market. It should be interesting to
watch the language at work in AI applications that have heretofore
been the province of Lisp, a language that is much more difficult to
use and understand. Who knows? We may yet se business applications
done in Logo. Logo is definitely one of today's most popular languages
for use in computer education--and rightly so. It is a language that
allows the child's (and adult's) natural ingenuity to trigger learning
without effort. What could better educational tool could there be?
Products: Color Logo (computer program)
Smart Logo (computer program)
Apple Logo (computer program)
Apple Sprite Logo (computer program)
Terrapin Logo (computer program)
Krell Logo (computer program)
IBM Logo (computer program)
PC Logo (computer program)
Waterloo Logo (computer program)
Ladybug Logo (computer program)
[3]Embedded Linux | [4]Coffee | [5]Sports & Theatre Tickets |
[6]Concert Tickets | [7]Cream Reunion Tour Tickets | [8]The Odd Couple
Tickets | [9]Red Sox Tickets | [10]more links
__________________________________________________________
* [11]Back to previous page
* [12]View this issue's table of contents
References
1. http://www.atarimagazines.com/creative/
2. http://www.freedownloadaday.com/
3. http://www.timesys.com/
4. http://www.peets.com/
5. http://www.cheappremiumtickets.com/
6. http://www.cheappremiumtickets.com/Concert.cfm
7. http://www.cheappremiumtickets.com/Concert/Cream_Reunion_Tour.cfm
8. http://www.cheappremiumtickets.com/Theatre/The_Odd_Couple.cfm
9. http://www.cheappremiumtickets.com/MLB/Boston_Red_Sox_Tickets.cfm
10. http://www.atarimagazines.com/links/
11. javascript:history.back()
12. http://www.atarimagazines.com/creative/index/?issue=v10n12
reply here at comp.lang.logo and it will be crossposted back to the
LogoForum. The original author of this message is "Daniel Ajoy"
<***@gmail.nospam.com>.
I had this web page in my personal archive
[1] Classic Computer Magazine Archive
CREATIVE COMPUTING VOL. 10, NO. 12 / DECEMBER 1984 / PAGE 94
__________________________________________________________
[2]Daily Free Software Picks
A comparison of Logos: today's turtle is no slowpoke. (evaluation)
Richard Roth.
Turtles and mice are the "in" animals in the personal computer field
this year. As in nature, microcomputer mice have both supporters and
detractors, but almost everyone agrees that turtles are beneficial
beasts--on the screen as well as in the stream.
The main role that computerized turtles play these days is in the Logo
language, a language that has journeyed from the Artificial
Intelligence Lab at MIT where it was developed to the classrooms of
the world in hust a few years.
The main difference between Logo and other languages is that Logo is
intended to encourage learning by using the power of the computer,
rather than being designed for writing programs. The child learns what
a computer can do while working with familiar concepts from the world
around him. The language demonstrates concepts by ignoring them and
allowing the user to cause results immediately and understand them
later.
The original Logo work done at MIT has evolved, through use, into an
effective core language. Two main categories of enhancements, sprites
and advanced programming features, distinguish the various current
versions of the language from one another.
Since Papert's work was financed with NSF grant money, early versions
can be licensed through MIT. Most of the advanced versions of Logo
have been developed by Papert's associates at Logo Computer Systems,
Inc. (LCSI). Let's have a look at some of the enhancements that have
been added by this and other companies. Sprites and Demons
A sprite is very much like one of Stephen Speilberg's Gremlins. It is
something to which you give the initial impetus and which then
continues on its own. Fortunately, you can interrupt it from time to
time to give it new instructions.
Sprites add to Logo the ability to set events in action and wathc the
results. The child can define a rule or a series of rules and then sit
back and watch them at work.
A demon is an "event" or action that is triggered by a timer, an input
device (such as a joystick or paddle), or the collision of two
sprites. An example is a procedure in which two trucks travel back and
forth across the screen. A cat runs on a path perpendicular to the
path of the trucks, and when either truck collides with the cat (don't
worry, the cat never seems the worse for the wear), it meows loudly.
The trucks and cat are sprites, and the cat's voice is a demon
triggered by the collision of the sprites.
Logos that offer sprites are all based on a specific graphic chip, the
TI 9918/9928 which was developed by Texas Instruments just for Logos.
Therefore, sprites are found only in Logos for the Apple with an
add-on sprite board and the Coleco Adam and TI 99/4A which have sprite
hardware built in. there is no reason that a sprite Logo could not be
developed for a high powered machine like the IBM PC or PCjr, but as
yet no one has done it. Advanced Programming Features
The advanced programming features offered by some versions of Logo can
bring the language into the realm of Artificial Intelligence
programming previously dominated by Lisp. As a replacement for Lisp,
Logo has some advantages because of its clearer syntax and better
support environment.
In addition to the standard list processing features of Logo, Digital
Research's Dr. Logo and LCSI's Logo offer good string and variable
manipulation capabilities. So far, however, Logo has been used mainly
in the lower grades and the real power of these capabilities has been
lost on most of the teachers using it. While the physcial connection
of turtles and sprites is clear, the list processing power of Logo
seems to be obscure to many users. Features to Compare
The basic feature of all Logos is the turtle. In addition, some Logos
offer multiple turtles, either as static objects or as sprites. All
Logos allow you to change the color of the turtle and its track, and
some even allow you to change the shape of the critter.
The programming features of all Logos are based on a procedure called
the TO, as in TO SQUARE--to draw a square. The basic language features
are loops (REPEAT) and tests (IF). As a Logo becomes more advanced,
variables are added using MAKE and then lists with such operators as
FIRST, BUTFIRST (all but first), LAST, and BUTLAST. And since lists
can contain both words and sublists, the concept of a sentence--a
simple list of only words--can be introduced.
The real power of any language is demonstrated in the way it interacts
with the machine on which it is running. For Logo, this interaction
starts with the color screen and extends to the keyboard and other
input devices. The ability to save and print procedures is a
requirement for any serious use. Unfortunately, most Logos lack the
ability to print the graphic screen.
The other important feature to consider in assessing the
sophistication of a Logo is disk operation. Complexity of disk
function ranges from simple text "stream" files to full file system
access. The Reviews
In trying to order the following collection of product reviews, I
settled on the price of the hardware system as an impartial order that
would be of at least casual interest to most users. The result is a
mixture of descriptions of Logos of different levels and ages, and
should be read accordingly. TRS-80 Color Logo
As the lowest priced system for which Logo is available, the 16K
TRS-80 Color Computer 2, is of more than passing interest to many
schools. The cartridge version of Logo for this machine is the basis
for a full education-oriented teaching system which includes student,
teacher, and parent manuals and a full set of transparencies for use
in the classroom.
The package concentrates on the turtle graphics functions of Logo with
a couple of interesting twists. Because it is intended for a very
small machine and beginning educational use, the package provides a
good set of turtle manipulation functions. Going are beyond the single
turtle provided by most of its competitors, this Logo offers the
sprite-like ability to define up to 255 turtles, each of which can
have a different shape and be controlled independently.
An additional feature, which is clearly aimed at very young users, is
the dooble mode. In this mode, the child can control the turtle with
single keystrokes. The resulting picture can be captured as a Logo
procedure and then edited as the child's familiarity with the language
increases.
Commands in Color Computer Logo are limited to those that control the
motion of the turtle complemented by SEND, MAIL, NEAR, and ME to
control multiple turtles. The Shape command sets the shape of the
turtle.
Users who have peripherals will be glad to note that this Logo reads
the paddles and allows procedures (but not graphics) to be printed.
The language as implemented by Tandy has a few minor oddities, the
most significant of which is the use of parentheses instead of square
brackets in statement lists. This change was made in deference to the
Color Computer keyboard, which has no brackets, but it detracts
somewhat from the ability to generalize Logo concepts from one system
to another.
The language is well complemented with manuals for the student and the
teacher. Particularly notable are the Color Logo Guide for Teachers,
Book One, and The color Logo Guide for Parents, Book One. Both books
are co-authored by computer education pioneer Bob Albrecht and offer
excellent step-by-step pictorial lessons. Disk Version
The only difference between the cartridge and disk versions of Color
Computer Logo is that using the disk is far easier than loading and
storing procedures from and to audio tape.
The only drawback to the disk version is that the disk operating
system occupies a great deal of memory, so the language cannot be used
on a 16K system. the addition of the extended memory option and disk
drive changes the nature of the system, removing it from the realm of
truly low cost computing.
A boon to users of the larger 64K Color Computer II would be an
advanced version of Logo that has been hinted at by Tandy. Some Tandy
watchers speculate that the new version will work with the company's
recently released color printers-- a delightful thought. Teacher's
Package
The Teacher's Package offered by Tandy may be a cost-effective
solution for schools that want the convenience of disk access for
multiple computers. The Package is actually a system which uses the
Radio Shack Network 2 Controller to connect up to 16 16K Color
Computers to one disk drive.
Also included in the package are a teacher's manual, overhead
transparencies, and individual student handbooks.
This is a very impressive package, and if he Logo it supported were
just a bit more sophisticated, I believe it would capture the hearts
of teachers on all levels. As it is, it does an excellent job of
supporting the first level Logo class, but falls short for more
advanced users. Coleco Adam
Smart Logo for the Coleco Adam is one of the latest versions of Logo
from LCSI and benefits from all this venerable organization has
learned about building and packaging Logo systems. It comes on an Adam
tape cartridge and begins with a very complete interactive tutorial.
The tape also includes demo programs and tools for advanced users.
Smart Logo benefits from an accident of fate which makes it one of the
best Logos I have seen. The basic ColecoVision game machine upon which
the Adam is based, uses the TI 9918 graphics chip described above, and
just as this chip gives ColecoVision games a great deal of extra
pizzazz, so it adds a whole new dimension to the Logo language,
including sprites and demons.
Smart Logo is a full implementation of Logo with all of the functions
described in the introductory section of this article. Its only faults
can be attributed to the fact that the Adam is a 64K Z80 system that
suffers from the basic memory and speed liminations of an 8-bit
processor, liminations that will escape the notice of all but the most
ardent and advanced programmer.
For graphics and sound, this Logo offers support of the Adam game
controllers and a set of functions to control the four-channel sound
generator built in to the computer. Procedures and graphics can be
saved, but only procedures can be printed on the character printer.
The Coleco system uses tape cartridges for storage, and although it
does take two minutes to get the system up and running, the matter
turns out to be of little concern because the tape is accessed only
rarely. My only real complaint about the tape system is that the
command SAVE can not be used to replace an old file nor to create a
backup. In my test situation, this meant that children had to be
taught about backup filenames and deletion of old files, a process
that lead to lost files and some tears before it was understood.
The disk drive, which Coleco has promised for the fourth quarter of
1984, will support all the functions now available with the tape drive
at considerably improved speed.
The manual is a small format loose-leaf binder. It includes a tutorial
section and a reference section that provides detailed examples and a
good index. At the back of the manual are a reference card and an
errata sheet. Apple II+, IIe, and IIc
Even though the original work on Logo for microcomputers was done on
the TI 99/4A, the various Apple versions of the language have been
driving force behind the widespread acceptance of Logo in the
educational community. Logo was first implemented on the Apple through
an NSF grant at MIT, and MIT has since licensed the software and
manual to two suppliers, Terrapin and Krell. Both companies offer
basically the same Logo with vastly different levels of documentation
and support for their customers.
In addition, the version of Logo developed by LCSI for the Apple and
Atari computers has been adopted as the official Apple version and has
been enhanced, resulting in two more versions--one with an add-on
hardware board for sprites. MIT Logo
MIT Logo is a combination of turtle graphics functions and list
processing functions. The turtle uses an Apple shape table and so may
be changed by more sophisticated users.
Other features of the Apple that lend themselves to Logo are the Apple
graphics screen which offers six colors and a nice work area for the
turtle, and the disk drive which can be used to save procedures and
pictures, either of which can be printed in black and white.
The MIT version of Logo has a a full set of statements for turtle
graphics and procedure writing. There are also list and sentence
processing operations and the ability to add assembler primitives.
The screen editor works smoothly except for the problem of square
brackets for enclosing lists on older computers. Like the
ColorComputer, the Apple II and II+ lack brackets on the keyboard, and
to get them on the screen, you must press Shift-N and Shift-M, which
can be a bit awkward. The problem does not exist on the Apple IIe and
IIc, both of which have square brackets on the keyboard.
You can interact with MIT Logo procedures by using primitives for
either the keyboard or the game paddles.
Utilities includes with MIT Logo can aid the beginning programmer with
examples and provide the advanced programmer with an assembler that
saves 6502 machine code directly. The exact set of utilities varies
with the supplier; however, both include the assembler and sample
programs like Rocket, the game of Animal, a single key doodle mode
called Instant, the music interface to the Apple speaker, and a
general file utility. Krell Logo
Krell Logo is the original MIT Logo with some interesting but not very
significant additions. Included in the package is a wall chart that is
useful for experienced programmers but can be confusing for the
beginner.
The introduction of the language is handled in a disk called Alice in
LogoLand. The package is a good introduction, but has some awkward
features that make it less effective. The documentation itself is a
reprint of the original MIT technical manual and is a bit of a
hodge-podge.
In sum, the Krell package is reminiscent of the state of the art in
1981 when it was first released. The intention is good, but it comes
off poorly. The main advantage of this package is the backup copy of
the boot disk that comes with the original. Terrapin Logo
The Terrapin version of MIT Logo is a considerably more advanced
product than the Krell version. Terrapin has enhanced both the
usefulness and the friendliness of MIT Logo with a complete user
tutorial and two unusual peripherals for its language.
The first peripheral, the Terrapin robot turtle, is a mechanical
turtle that can be controlled using Logo commands just as the graphic
turtle can. It is fascinating to experiment with a three-dimensional
object under program control. Unfortunately, the $300 price tag tends
to keep the turtle out of the hands of most children.
The second peripheral offered in conjunction with Terrapin Logo is the
Micro Mint Sprite Board, the first attempt to make sprite graphics
available on the Apple. While the attempt is less than completely
successful, it does demonstrate what can be done with sprites on the
Apple. The main problem with the system is that it requires two
monitors--one for the video from the Apple and one for the video from
the sprite graphics processor. For the hobbyist or experimenter, the
product is challenging and fun to use; for the classroom, it is just
doesn't make it. Apple Logos from LCSI Apple Logo--The Original
The LCSI Logo that became the official Logo for the Apple is a
smoother language than either of the two versions of MIT Logo. The
package comes with a reference manual and a tutorial that are as good
as or better than the best parts of both the Terrapin and Krell
versions.
The LCSI language lacks some of the more interesting features of the
MIT version, including the ability to save pictures to disk, and call
assembler routines. Also lacking is the utility disk. These are all
features that are of use primarily to the advanced user.
On the other hand, LCSI has added some features that will be welcomed
by users who plan to write lessons in the language. These include
cleaner syntax for logical operators like AND/OR, packages and buried
packages, property lists, and error THROWing and CATCHing. Apple Logo
II
Logo is not a static or stagnant language, and LCSI continues to
enhance and improve it. The latest official Apple Logo offers a
revised set of manuals and a set of file operations (called
primitives) that allow it to be used with ProDOS on a 128K Apple IIe
or IIc. The only problem I observed was that a system this large
begins to tax the speed of the Apple disk drives when loading
initially or using the disk heavily. With a hard disk, of course, this
problem vanishes.
The new, improved Apple Logo from LCSI is excellent for beginners and
more than adequate for advanced AI applications.
A second improved version of Logo from LCSI comes with a sprite board
that can be used with the Apple II+ and IIe. Since the language itself
was designed to take advantage of the sprite board, all graphics and
text appear on the same video display.
The package includes extensive examples that demonstrate how to
control sprites and redefine the shapes of existing characters. The
only function not provided by the TI 9918 chip on the add-on board is
the use of demons. There are, however, similar functions that test for
collisions between turtles and/or sprites. IBM PC
As with every other category of software, the market presence of IBM
has inspired a large assortment of Logo packages for that machine. The
graphics capability of hte PC ensures that all versions score well in
that area. Much to my surprise, however, none of the available Logos
for the IBM offers sprites, even though the 8088 processor can support
them through software. Instead, the PC Logos have concentrated on
advanced programming features. IBM Logo
As the official IBM Logo, this LCSI package is matched only by its
sister product for the Apple. It features both a complete manual with
reference and tutorial sections and the most complete language
available.
As mentioned above, this Logo lacks sprites, but its full file system
access makes it the implementation of choice for advanced users in
both AI and teaching situations. For beginning users, the only
drawback--and it is a small one--is the depth of hte supplied example
material.
The language is all there; it is hard to say more without being
repetitious. All the turtle graphics commands are supported as are the
programming and list processing features. Graphics are supported by
the standard IBM hardware without low level access, and hackers will
appreciate an assembler call facility that resembles Basic.
The only feature that advanced programmers will miss is subdirectory
support, a lack attributable to the fact that IBM Logo is not yet
available in a DOS 2.0 version.
Despite the fact that it is an official IBM product, I had difficulty
obtaining a copy of IBM Logo. So if your local store denies all
knowledge of the product, persevere; it does exist and is well worth
the effort once you find it. PC Logo
PC Logo from Harvard Associates is a good version of a turtle graphics
Logo with all the extended features needed for advanced programming.
The package makes good use of the PC function keys and is well adapted
for the IBM machine.
Extra primitives allow for very simple and complete control over the
PC screen and other hardware devices. Again, hackers will appreciate
direct access to PC DOS and the BIOS ROM as well as many other low
level features. The only thing missing is an assembler call.
At the same time, PC Logo can be used with ease by a child or
relatively inexperienced grade school teacher.
The manual has an esy to read tutorial and a complete reference
section packaged in an IBM-sized binder. A good set of examples is
included on the disk, and a reference card completes the package.
Harvard Associates offers a complete Logo package to schools, which
includes volume licensing plan and price incentive.
Not part of the package, but a peripheral that schools should consider
buying is the Turtle Tot, a robot turtle that accepts its commands
from PC Logo. Also available for the Apple, the device is a favorite
among children of all ages. Waterloo Logo
The University of Waterloo, long known for such favorites of computer
science majors as the WatFor and WatFive fast Fortran compilers, has
lately been working on a set of microcomputer tools, including a
networking system and a language set to complement it. With this
background, it is easy to understand the role of Waterloo Logo, an
implementation that would probably not survive on its own.
The package is well done, but terse. It includes a reference card and
a manual "writeen for people who already have programming experience
using a high level language."
The language as implemented here is a good basic Logo system which is
well adapted for the IBM PC, but as a competitive product it just
cannot hold its own. LadyBug Logo
One of the most impressive Logos for the PC is impressive not because
of its fancy packing or its great manual or even its fantastic
features. It has no packaging its manual is only fair; and its
features are complete, but not fantastic. No, the package is
impressive because of its price; it is free.
LadyBug Logo is freeware, and unfortunately, while people seem willing
to pay $35 for a copy of PC-Talk, PC-Write, or PC-File, they are
reluctant to pay for an educational package. Dave Smith, the author of
LadyBug Logo, requested that users make a donation toward further
development work. Sadly, he reported that barely 1% of the 500 people
to whom he has sent copies have sent him any money. I promised him I
would challenge the readers of Creative Computing to prove that
educational freeware can pay. Copies are available from the Young
People's Logo Association and on many PC bulletin boards.
As for the language, itself, it is a full turtle graphics language
with disk procedure storage and a good set of examples. The 84-page
manual is on disk and includes a good index.
Special features of this version of Logo are a PLAY function for
music, access to joysticks, and a full screen procedure editor.
Running under DOS 2.0, the language allows graphics screens to be
printed and just fits on the PCjr.
For advanced users, there is a good debugging mode, but the package is
show--about half as fast as most of the other PC Logos--even though it
is written in compiled Basic. Logo for Other Computers
In addition to the products discussed above, there are also Logos for
the TI 99/4A, Commodore 64, and Atari computers. Computers for which
versions of Logo will soon be released include the DEC Professional,
Macintosh, Sanyo MB550, and TI Professional. Logo for the Future
I predict that we will continue to see enhanced and improved versions
of Logo. Most will come from LCSI, which has established itself as the
main supplier of the language and has used its relationship with
Seymour Papert to enhance the language and encourage educational
programs to use it.
I have even seen some evidence that disk versions of Logo are being
aimed at a wider audience than just the parents, teachers, and
children who make up the education market. It should be interesting to
watch the language at work in AI applications that have heretofore
been the province of Lisp, a language that is much more difficult to
use and understand. Who knows? We may yet se business applications
done in Logo. Logo is definitely one of today's most popular languages
for use in computer education--and rightly so. It is a language that
allows the child's (and adult's) natural ingenuity to trigger learning
without effort. What could better educational tool could there be?
Products: Color Logo (computer program)
Smart Logo (computer program)
Apple Logo (computer program)
Apple Sprite Logo (computer program)
Terrapin Logo (computer program)
Krell Logo (computer program)
IBM Logo (computer program)
PC Logo (computer program)
Waterloo Logo (computer program)
Ladybug Logo (computer program)
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