
THE FOREST

A COMPUTER SIMULATION OF THE SPORT OF ORIENTEERING

BY

GRAHAM T. RELF


PHIPPS ASSOCIATES
172 KINGSTON ROAD, EWELL,
SURREY KT19 0SD


ISBN 0 946460 02 7


(C) COPYRIGHT 1983 PHIPPS ASSOCIATES
ALL RIGHTS RESERVED

Photocopying of this book is expressly prohibited.
The purchaser for full retail price may make a
security copy of the accompanying cassette.
Making more than five copies is prohibited as is
disposing of such copies to third parties, even by
way of gift. It is a condition of sale that this
product shall not be lent or hired by way of trade
and that a similar condition must he imposed on
any subsequent purchaser.



		TABLE OF CONTENTS

SECTION					PAGE

1	INTRODUCTION			5

2	ORIENTEERING - THE SPORT	7

3	STARTING THE PROGRAM		9

4	THE DISPLAYED SCENE		11

5	SIMPLE COMMANDS			16

6	FINISHING THE COURSE		19

7	NAVIGATIONAL TECHNIQUES		20

8	THE MENU			23

9	PLANNING A NEW COURSE		31

10	SOURCES OF FURTHER INFORMATION	31



First Edition August 1983
Second Edition November 1983
Version 3.1

Printed by:

Ward and Woolverton Ltd.,
92 Church Road,
Mitcham, Surrey CR4 3TD



1. INTRODUCTION

This book contains a description and operating manual for the
program "The Forest" which runs on the Sinclair ZX Spectrum
(48K). A version is also available for the TRS 80 computer. To
participate in the game you will need to have a ruler graduated
in millimetres and a geometry protractor, for measuring angles.

The main feature of the program is a real-time simulation of the
sport of orienteering, in which the user of the program becomes a
competitor. Orienteering has been described as "car rallying on
foot". It is essentially a cross-country race across difficult
terrain (usually forest) to which has been added the extra
dimension of navigational problems, though not cryptic problems
of the "treasure hunt" kind.

The program is intended to be useful as a training aid to
orienteers as well as being a game in its own right. In
particular it can assist with the interpretation of contours for
navigation, which is one of the most difficult techniques to
master in orienteering. This is assisted in the program by
displays showing cross-sections through the terrain, contoured
three-dimensional views, or maps of any part of it at any chosen
scale, contour interval or orientation. Such displays complement
the normal view presented by the program which is of the
scene ahead when standing on the ground at some point in the
forest, with trees and other objects all around.

When moving through the forest in the program, the size of paces
and your bearing both drift slightly as they would in real life.
You can therefore practise distance estimation and aiming-off
techniques as in a real orienteering event. Furthermore your
running speed depends on the type of terrain and on the steepness
of hill, so realistic route choices are required between
controls. The forest is enormous (effectively limitless) an
only a small portion has so far been mapped, so unless you are an
intrepid explorer, be warned! The forest contains no linear
features other than vegetation boundaries and the edges of towns
and lakes (ie. there are no roads, fences, streams, etc.) This

5

is to make navigation more difficult for training purposes.

The program can be used to introduce novices to many features of
the sport of orienteering and also to train map makers. It is
also likely to be of value to Geography teachers, particularly in
demonstrating the relationships between maps and the physical
features that they represent.

A recent addition to the program is an option to switch to a much
more complicated forest with contours more reminiscent of the
marvellous terrains in the homelands of orienteering,
Scandinavia. A printed map of this is not yet available.

Figure 1  A control point with flag

[illustration]

6

2. ORIENTEERING - THE SPORT

At an orienteering event each competitor is given a detailed
printed map of the forest on which is drawn a course to be
followed. The course is normally marked in red as a series of
numbered circles joined by straight lines. The centre of each
circle is a feature printed on the map. This might be a
boulder, the corner of a thicket, the junction of two roads, or
whatever the course planner has chosen. The corresponding
feature on the ground has a red and white control flag next to
it, as depicted in Figure 1. The competitor has to visit the
marked control points in the numbered sequence but is free to
choose any route between controls; it is not necessary and
frequently impossible anyway to attempt to follow the straight
lines connecting controls on the map. As proof of visiting each
control the competitor also carries a "control card" illustrated
in Figure 3. This has numbered squares to be marked at the
controls. Each control flag bears a simple code of one or two
letters or digits which the competitor can check against a
description list to ensure that the correct control has been found.
An example of a description list is shown in Figure 2. Having
found the correct control, the correspondingly numbered box on
the control card is punched with a red plastic needle-punch
hanging next to the flag. The needles on these punches form
various patterns which can easily be checked afterwards.

	COURSE BLUE 5.6 KM.
	1  AF	ROOT STOCK
	2  AG	FODDER STAND
	3  AJ	SE EXTREMITY OF YOUNG TREES
	4  BF	SUMMIT
	5  BE	PLATFORM
	6  BD	KNOLL (1M.)
	7  BA	EARTH BANK (OLD QUARRY)
	8  AZ	MINE SHAFT IN KNOLL
	9  AW	DEPRESSION (2M.) IN KNOLL
	10 AV	MINE SHAFT
	11 AR	DEPRESSION (1M.)
	12 AQ	FENCE
	13 BS	JUNCTION OF DITCH AND E.-W. VEG. BOUNDARY
	14 BU	PATH BEND
	FOLLOW TAPES 200M. TO FINISH

Figure 2  A description list

7


Figure 3  A partially completed control card

[illustration]

8

The course is a race against time, with competitors usually being
started at intervals of at least a minute to prevent them
following each other. Other factors which prevent following are
that the forested terrain reduces visibility and that different
competitive classes (very often this means age groups) have
different courses going in quite different directions and
crossing each other. Any control flag found may well be on a
different course from your own so it is no good just looking for
the flags.

The start of the course is marked on the map by a red triangle
rather than a circle. The finish in shown by two concentric
circles. Neither the start nor the finish need correspond to
mapped features. There are usually long tapes laid out to
funnel competitors past the finish, so they all pass the time-
keeper in the same direction and in single file.

It should be pointed out that although there has been frequent
reference to competition in the preceding paragraphs,
orienteering is enjoyed by many people purely for the personal
challenge of pitting their wits against the map, course-planner
and terrain. It is this aspect which the computer program
captures best and it is hoped that it will encourage newcomers to
go and try the real thing.


3. STARTING THE PROGRAM

The program is supplied on a tape cassette in the standard format
for the ZX Spectrum. It consists of two program files which
must first be loaded into memory. The first is a BASIC program
called "forest" which automatically runs when loaded and loads
the second file. To load and run The Forest you need to do the
following:

LOAD "FOREST"	(start the tape - NOTE USE CAPITALS
		(stop the tape only when told to do so
		(by the program

9

The program takes a few seconds to get started. While it is
setting up the "course" it displays a title page. If you press
any key the screen will soon change to show the scene at the
start of the course. Race time is immediately running against
you and you should start moving an soon as possible. Race time
runs at exactly the same rate as real time, being read from
the Spectrum's internal clock. You can see the elapsed race time by
using the T command which will be described later.

The map with the course marked on it is the book jacket within
the outer cellophane cover of this folder. Remove it carefully.
The remaining sections of the book describe how to use the
program to navigate around the course.

10

4. THE DISPLAYED SCENE

Figure 4 is an example of a scene which might be displayed by the
program. This shows a number of different things which are
described in more detail below.

[illustration]

Figure 4  A scene displayed  by the program

Terrain  Symbols

Ten terrain symbols can be placed in a horizon six metres ahead
of you. For brevity we will refer to a terrain symbol as a tree
in the rest of this guide but it can take any of the following
forms:

A tall tree, often with only the trunk visible because the leaves
are off the top of the screen, represents mature wood through
which you could easily run. This terrain will be referred to as
runnable wood, or just "run". On an orienteering map such areas
are shown in white.

A short fir tree represents thicket. Young trees like this are
common in real forests and because their branches interlock they

11

can be very difficult to get through. The program takes account
of this and it is often wiser to skirt round such thickets. On
an orienteering map thickets are conventionally green.

A short tufted symbol represents tussocky moorland or heather.
This is also slower to move through than other types of terrain.
Moorland (the more general orienteering term is "rough open") is
printed in ochre or orange on orienteering maps.

A plain bar with no other symbol on it represents open grassland,
the fastest terrain to run across. Such open ground is
represented in bright yellow on orienteering maps.

A house symbolises a settlement of any size, referred to in the
program as a town. No orienteering features appear in the towns
and there are consequently no control flags there. Towns do not
often appear on real orienteering maps but the general symbol for
built-up areas is diagonal black and white line shading.

A flecked horizontal bar portrays the surface of a lake. The
program does not allow you to run through lakes; forward motion
stops with a warning message at the top of the screen. You could
wade across any lake by moving one pace at a time (i.e. by
pressing a key for every step) but this would be very slow.
There are of course no controls in lakes. Lakes are printed in
blue on orienteering maps.

The symbols are designed to be displayed in fairly natural
colours on a colour television set while also having adequate
contrast to be seen clearly on a monochrome set, though the
brightness control may need to be increased for the latter.

Each "tree" is positioned naturally enough, with its base showing
where the ground would be six metres away from you in its
direction. Their relative vertical positions therefore show how
the ground undulates ahead of you. The central two trees are
standing on the ground straight in front of you. All trees are
spaced at intervals of 11.25 degrees. This means that a 100
degree sector of the six metre horizon is visible 50 degrees to

12

each side. When you turn by using single keys (see later) the
scene shifts by the interval between trees; i.e. 11.25 degrees.
It therefore requires eight such turns to turn through 90 degrees
(there are more direct and precise methods of turning, using the
compass which will be described later). Figure 6 shows the
relationship between the horizon and you, the observer, standing
on the ground.

Figure 6  The observer and the horizon

[illustration]

Level Marker

This takes the form of a small (character-sized) flashing block,
always in the same position in the centre of the screen. It
shows where the base of the tree straight ahead would be if the
ground were exactly level. This enables you to see whether the
ground directly ahead slopes up or down and from that the
relative positions of the other trees show all the details of the
visible ground's height and slopes.

13

Description

A one-word description of the type of terrain where you are
currently standing appears in the lower left corner of the
screen. This word is one of the following, which describe the
terrain types in the same order as at the beginning of this
section.

RUN   THICK   MOOR   GRASS   TOWN   LAKE

Feature

If a ground feature is visible of the kind that might be used for
a control, then a description of it appears at the bottom of the
screen, to the right. These "point" features become visible in
this way if you are within about 5 metres (approximately 5 paces)
of them. You do not have to turn to see them; as long as you
are close enough they are announced on the screen (the
orienteer's ideal!). If you are more than 5 metres but still
within about 10 metres of a feature which has a control flag then
the flag appears in a fragmented form between the trees in the
general direction of the feature. You will see this as a set of
white character-sized blocks on the ground. In this case
turning around will affect the visibility of the flag and you can
turn to run more directly towards the control. The control will
then appear in the foreground as you get within 5 metres of it.

The following features can occur. Brief descriptions are given
here because the names used are orienteering terms, as they would
appear in the description lists for controls, and their
definitions are sometimes peculiar to orienteering. The
conventional symbols used on printed orienteering maps are also
described.

Boulder		A sizeable single stone lying on the ground.
		Usually at least 0.5 metres minimum dimension.
		Symbol: black dot.
Building	Self explanatory. Symbol: solid black rectangle,
		or for larger buildings, a silhouette.

14

Depression	A hollow which is too small to be shown on the map
		as a contour ring. At least 1 metre deep.
		Symbol: a brown V.
Knoll		A hill too small to be shown on the map as a
		contour ring. Symbol: brown dot.
Mine Shaft	A vertical sided rocky-walled depression, usually
		the blocked remains of an old mine-shaft, so it
		has a floor. Symbol: Black V.
Niche		A depression in the side of a hill, such that the
		exit on one side does not slope upwards. Symbol:
		Brown C, oriented with its mouth towards the level
		exit.
Pond		A water-filled depression. Symbol: blue V.
Rock outcrop	A very small cliff or rock step, at least 1 metre
		high. Symbol: black (like a Greek pi),
		oriented so that the top bar shows the line of the
		cliff and the two tags point down the step.
Root Stock	The upturned root of a fallen tree, typically 1-2
		metres high. Symbol: black X.
Ruin		Ruined building. Symbol: four black dots in a
		small square formation.
Sheep Fold	A ring of wall, too small to be drawn to scale on
		the map. Symbol: black circle.
Water Tank	Self explanatory. Symbol: square blue outline.

If the ground feature has a control flag by it, then a flag
symbol is shown in the bottom centre of the screen. If you are
not moving forwards, then you will see the flag's two letter code
painted on it.

Other text can appear at the top of the screen from time to time
to give you information or to ask you for something if you have
issued a command to the program. Some commands cause the normal
scene described above to vanish temporarily; for example, to
display the menu or a map.

15

5. SIMPLE COMMANDS

You communicate with the program by pressing single keys on the
keyboard. The following is a description of the effects of each
active key. When you have read and understood the description
you may like to use Figure 7 as a quick guide to which keys are
appropriate at any point in the program. Note that the arrowed
keys are the normal ones marked on the Spectrum; i.e. those
numbered 5 to 8, but they are used unshifted, to make them
easier. The other commands listed here require the CAPS SHIFT
key to be used, however, to prevent unintentional use.

Up Arrow

This starts you moving forward and motion continues until you
press the space bar. On each pace forward the scene is re-
displayed to show the view from your new position. One pace is
nominally one metre, but it varies randomly within +/- 10%. Each
pace forward also causes your bearing to drift by a random amount
of up to 1.5 degrees either way. During forward motion only the
left and right arrows can be used without stopping the motion;
other commands may be used but they will first cause you to stop.

Right Arrow

Turns you 11.25 degrees to the right (that is, one tree space or
1/8 quadrant). The scene slides to the left as you turn. This
turn can be done while you are moving forward, in which case it
takes the place of one forward pace (note this in case you want
to count paces to estimate distance travelled).

Left Arrow

Turns you 11.25 degrees to the left and the scene correspondingly
slides to the right. In all other respects the action is the
same as for a right turn above.

16

Figure 7	N.B. Arrow keys are unshifted (lower case)
		     Letter keys are upper case (use CAPS SHIFT)

[illustration]

17

Down Arrow

This causes you to turn right around through 180 degrees to face
back the way that you have come. If you were moving forward,
this command stops you.

Any Non-Arrowed Key

Stops you moving forward. You may need to hold the key down for
a moment before motion stops and the scene becomes static.

B (for Bearing)

Looks at the compass. Displays your present bearing (in degrees
clockwise from North) and asks for a new bearing to be set. If
you then type in any number in the range 0 to 360 (followed by
ENTER) you are turned round as necessary and the scene on display
is revised to show the new view. If you do not wish to alter
the present bearing, just press ENTER instead of typing a number.
Note that your bearing will drift when you move forward, by up to
1.5 degrees on each pace. It can even change slightly whilst
you are standing still (hopping from one foot to another
perhaps). Remember also that you cannot read a real orient-
eering compass to better than a couple of degrees, especially
when moving.

C (for Control Card)

Clears the screen and displays the control card, complete with
the codes of any controls which have been punched. Pressing any
key returns you to the forest scene.

D (for Description List)

Displays the description list for your course. This gives the
number code and description of each control you have to visit.
Pressing any key returns you to the normal forest scenes.

18

M (for Menu)

Clears the screen and displays a menu of numbered options.
These enable you to find your exact position, draw maps, cross-
section, or three-dimensional views of any part of the forest,
or to give up the course. Most of these are penalised commands,
because you would not be able to do such things in real orient-
eering. The menu options are described in more detail in
subsequent sections.

P (for Punch)

If a control flag is visible this command will put its code in a
square of the control card. The program first asks you for the
number of the square which is to be marked. This should be the
number of the control in sequence on the course. You must make
sure that you have found the correct control before punching, by
using the D command and by looking at the code on the flag, for
which you must first stop moving. The program does not prevent
you from punching an incorrect square. You can examine the card
before and after punching by using the C command.

T (for Time)

Looks at your watch to display the elapsed race time.

6. FINISHING THE COURSE

To complete the course it is only necessary to move within about
five metres of the finish point marked on the map (the centre of
the two concentric circles). You may approach the finish from
any direction. The program detects when you are close enough to
the finish. It then clears the screen, reports any codes which
are wrong or missing from your control card, and shows the
elapsed race time, in hours, minutes and seconds. It also shows
the number of times that you cheated by using the penalised
options on the menu. The program then stops, but you may run it
again, if you wish, by entering the BASIC command: GOTO 5

19

7. NAVIGATIONAL TECHNIQUES

Do not under-estimate the difficulty of navigating through The
Forest, even if you think that you are a good map reader. The
following factors make navigation particularly difficult:

-	There are few "handrails" to follow; there are no roads,
	paths or streams. You can, however, follow vegetation
	boundaries and the edges of towns and lakes.
-	The direction of motion, your bearing, drifts as you move
	forward.
-	The length of your pace varies, so counting your paces only
	gives an estimate of the distance travelled.

The first of these factors is deliberate, to make navigation less
easy. The other two reflect the real difficulties encountered
in the sport of orienteering. There are techniques for minim-
ising these difficulties and some simple rules will now be given.

Always count your paces as you move; i.e. the number of times the
scene is redisplayed. The distance travelled is then, within +/-
10%, the same number of metres on the ground, or 1/10 millimetres
(mm) on the 1:10,000 scale printed map:

	1mm on map = 10 metres on ground = 10 paces.

Use the B command regularly to confirm that you have not drifted
too far from the direction you have set with the compass, and to
correct it if you have.

Always stop moving while you check your position on the map.
When you gain experience, you will be able to keep relating the
displayed scene to the map as you move and then you will need to
stop less often. To begin with you should err on the side of
caution.

Because bearings drift an you move, you must not expect to be
able to hit a point feature by aiming directly at it from more
than about 50 metres away (5mm on the map). Instead you should

20

aim for a larger feature, perhaps a town or a lake. When you
reach that, find a corner from which to aim for the point feature
or for another one to use as a "stepping stone". If the initial
large feature (or "collecting feature" in orienteering terms) is
to one side of the small feature you are seeking, then you must
deliberately aim towards that side so you can be sure of finding
the larger feature. This technique is called "aiming off". As
an example, consider the first leg of the set course in the
program. One way of finding the first control is to set a
bearing of 50 degrees before moving off. This points you
towards the lake 140 m north-east from the start. Count paces
as you go, and stop to check your bearing at least every 40 m; if
it has changed by more than three or four degrees, then correct
it before continuing. You should see the lake after 150 paces
at most. Turn to the right as you approach, to look along the
shore with the lake on the left and tall trees on the right.
Stop again to take a bearing which will either confirm that you
are on the southern edge of the lake (bearing about 90 degrees)
or, if you drifted left, the western edge (bearing about 180
degrees). Following the southern edge of the lake for anything
up to 60 paces you will suddenly see the lake disappearing off
the left-hand edge of the screen and the ground ahead beginning
to rise. This means that you are at the south-east corner of
the lake. Here you should stop again to set the direct bearing
of 93 degrees to run about 40 paces uphill to the depression.
You may see a niche on the way, confirming your course, but do
not worry if you miss that. If you miss the target depression,
you are almost certain to meet the town behind it, so you cannot
go far wrong. Subsequent controls do not have such safety nets
behind them, however.

Suppose you do get lost - what then? The golden rule is to stop
moving. Do not be tempted to explore the vicinity at random -
you would only move further from the last place where you knew
your position. Having stopped, carefully review the moves you
have made since the last time you were sure of your position.
Then take a bearing, so you know which direction you have come
from. Next, examine your surroundings, without moving from the
spot, and try to relate them to the map. This will rule out

21

many locations. Study the slope of the ground ahead and to
either side; whether it is rising or falling and its relative
steepness. Check the type of terrain that you are standing in
and turn round slowly to see the terrain types on the 6m horizon.
If a point feature is visible, its description may immediately
narrow the possibilities down considerably. If, on turning
around, you see a control flag through the trees then you could
move towards it and stop there to see what kind of feature it is
on. Doing all these things will probably provide quite a short
list of possible locations and you will need to start moving to
confirm one of them. Try to find a large feature on the map
which is near the suspected location. Set a bearing and move
towards it, counting paces. Stop very frequently to check your
bearing so you could retrace your steps if necessary. Do not
move too far at a time until you know where you are once again.
If you are really stuck the program provides a way out, which is
not available in real orienteering: use Option 1 on the main menu
(command M for Menu), to obtain your coordinates, x and y. Sub-
tract 1000 from x, divide by 10 and measure that number of mm
eastwards from the left side of the printed map. Subtract 1700
from y, divide by 10 and measure that number of mm northwards
from the bottom edge of the map. The intersection of these two
measurements gives your position on the map. If you resort to
this method, however, the program will later expose you as a
cheat!

When you become more proficient, the contours can be used for
navigation across featureless areas, instead of following bound-
aries or aiming off. Although it is abstract and invisible you
can follow a contour by steering to keep the level marker in the
displayed scene as close as possible to the base of the central
tree symbol.

Of all these rules, the most important is to stop moving and
think whenever you are in doubt, despite the fact that race time
is running against you. It is surprising how quickly you can
move away from a known position when you are not concentrating.

Finally, it must be borne in mind that, like computer software,

22

no map is ever perfect. The one supplied with this program is no
exception. While every effort has been made to ensure accuracy,
it is possible to find features which are not on the map. The
immediate surroundings of each control on the set course have
been checked particularly carefully, however. If you use the
Course Planners menu you should also explore the neighbourhood
of each control carefully first, as would be done by the planners
and controllers of real orienteering events.

8. THE MENU

When the forest scene is visible, the M command causes the screen
to be cleared and a list of numbered options is displayed:

	THE FOREST : MAIN MENU

	0) Return to scene (no penalty)
	1) Get coordinates
	2) Map terrain types
	3) Map contours
	4) Scan for point features
	5) Draw cross-section
	6) Draw 3D view
	7) Give up (stop)
	8) Go to more complex forest
	9) Alter the set course

	Which?

	NB: 1 to 6 are not possible in
	real orienteering, so they are
	counted as cheating and will be
	reported at the finish.
	After an option any key returns
	to this menu.

Most of the options on the menu are not the sort of thing that
you could do in real orienteering and therefore the number of
times you use them is added up by the program and held against
you at the end. Their purpose is instructional, to show the
relationship between the map and the ground in various different
ways. We will describe them in more detail but there are two
general concepts to mention first: coordinates and the means by
which the program will prompt for information to define an area
to be mapped or drawn.

23

Any position in the forest, such as where you are standing, is
represented in the program by Cartesian coordinates, x and y,
each measured in metres. These are similar to grid references
in map terms: x is the number of metres measured east from some
fixed reference point and y is the number of metres measured
north from the same point. X distances should always have 1000
added to them. Y distances are measured from the bottom of the
map and should have 1700 added to them. Remember that 1mm of
map = 10 metres.

When you select any option which will result in a map or view of
some portion of the forest you will first be asked to define that
portion. The program uses a standard diagram and a series of
prompts for the definition, with minor variations for the
different types of drawing. The following items have to be
entered in response to the prompts.

The coordinates (x0 and y0) of the bottom left hand corner of
the portion of terrain to be plotted. If you wish to draw a map
or view around your current position, you should first use Option
1 on the menu to obtain the coordinates of that position.

You then have the option of entering either the width and height
(in metres) of the rectangular area to be plotted or the scale of
the resulting map. Scale is used in a relative sense here,
because different televisions will of course draw the map at
different sizes. If you specify a scale of 1:n,000 this really
means that the program will plot the terrain for a square grid of
points every n metres on the ground. The most useful aspect of
this appears when you draw successive maps of a similar area at
various scales and compare them. Whether you specify width and
height or scale, all these values will then be displayed on the
screen. This will enable you to see the width and height corr-
esponding to a given scale and vice versa. Note that for cross-
sections (menu option 5) only the width and x-direction scale
are relevant and a modified diagram is presented by the program
to guide you.

24

	[illustration]

	x0 = 1366       w = 500 m.
	y0 = 2332       h = 500 m.
	x scale = 1:15625
	y scale = 1:20833

An angle b defines the orientation of the map. This angle is the
bearing (clockwise from North) of the bottom edge of the map.
For a conventional upright map b would be 90 degrees. The
ability to specify this angle is particularly useful for the
three-dimensional views (menu option 6). Suppose that the xy
coordinates specify the middle of a lake; whatever orientation or
angle is chosen for b that lake will always be at the left-hand
bottom corner of the screen. For a 90 degree value of b north is
at the top of the screen; for a 180 degree value of b north is
the left-hand edge of the screen; for a 270 degree value of b
north is at the bottom of the screen; for a 360 or 0 value of b
north is at the right-hand edge of the screen.

For contour maps only (menu option 3) you must also select a
contour interval. The program will accept values in the range
from 1.25 to 80 metres, but the actual contour interval used will
be the nearest value in the following list which is less than or
equal to your specified value:

	1.25, 2.5, 5, 10, 20, 40, 80

Usually 5 metres is a suitable interval to specify, but it is
instructive to try various intervals on successive maps of one
area.

25

For point-feature scan only (menu option 4) you must specify a
step size. The point-feature scan is a means of finding all the
point features in any rectangular area. The area has to be
defined in the same way as for maps, but when you have done that,
the program will take you for a fast ride through the forest in a
raster-scan pattern. This first goes north, along the left edge
of the rectangle, then turns through 180 degrees and brings you
back along an adjacent strip, rather like mowing a lawn. When-
ever a point feature is visible, the program pauses to let you
see it, its control flag (if any) and the code on its flag. As
your coordinates are continually displayed in the top left corner
of the screen during such a scan, this provides a means of
plotting every feature on a map and listing their details. To
continue from a pause press any key. SPACE will return you to
the menu but any other key will continue with the raster scan.
This process had to be done to prepare the printed map of the
forest and to plan the course. Returning to the step size: point
features are visible in an 8 metre square. It is therefore
sufficient to specify an 8 metres step size if you wish to see
every feature in your rectangle (except for a very few which are
close to lakes and towns).

The display screen of the Spectrum having only 32 by 24
addressable blocks of colour, does not lend itself to the
detailed full-colour cartography usually used for orienteering.
In this program no attempt has been made to display full graphical
maps. Instead the information has been split into three types
for separate display. All the examples in the figures which
follow have been taken with the coordinate reference of the start
1366/2332 and specify a square 500 metres by 500 metres with an
orientation of 90 degrees.

Terrain types (menu option 2)

A grid of letters in 24 rows of 32 columns is displayed to
represent a component of the map. The letters are simply abbr-
eviations of the type of terrain at each point and they are on
coloured squares following the colour conventions of orienteering

26

maps as far as possible:

	L  Lake			blue
	S  Settlement (town)	black
	T  Thicket		green
	R  Runnable wood	white
	M  Moor			magenta (there is no ochre)
	G  Grass		yellow

Figure 8  Terrain type map

	trmmllllmmmmmmrrrrrrrmmmmmmmmmmr
	rmmmmmmmmmmmmmrrrrrrrrmmmmmmmmmr
	rmmmmmmmmmmmmrrrrrrrrrmmmmmmmmmr
	mmmmmmmmmmmmrrrrrrrrrrmmmmmmmrrr
	mmmmmmmmmmmrrrrrrrrrrrrmmmmrrrrr
	ttmmmmmmtttttrrrrrrrrrrmmrrrrrrr
	rrrrrmrttttttrrrrrrrrrrrrrrrrrrr
	rrrrrrtttttttssrrrrrrrrrrrrrrrrr
	rrrrrtttttttttrrrrrrrrrrrrrrrrrr
	rrrrrrrrrrtttttrrrrrrmrrrrrrrrrr
	rrrrrrrrrttttttrrrrrmmmmmmrrrrrr
	rssssrrrtttttttrrrrrmmmmmmmrrrrr
	rssssrrrrtttttttttrmmmmmmmmrrrrm
	rrrrrrrrrttttttttttmmmmmmmmrrmmm
	rrrrrrrrrrtttttttggmmmmmmmrrrrmm
	rrrrrrllrtttttttgggmmmmrrrrrrrrr
	rrrrrrlllltttttggggmggrrrrrrrrrr
	rrrrrrlllltttttgggggrrrrrrrrrrrr
	mrrrrrllllrrrttgggrrrrrrrrrrrrrr
	mrrrrrllllrrrrrrrrrrrrrrrrrrrrrr
	rrrrrrrrrrrrrsssrrrrrrrrrtttrrrr
	rrrrrrrrrrrrrssssrrrrrrrtttttttr


Contours (menu option 3)

A 24 by 32 grid of letters is again used. This time the letters
represent height bands: the higher the ground the later the
letter in the alphabet. The assignment of letters to height
ranges depends an the contour intervals you have chosen for the
map. Colours are also assigned to the height bands to make them
easily distinguishable. The Spectrum's eight colours are used
in rotation as height increases.

27

[pages 28-31 are missing]

Other Software from Phipps Associates


Books	The Spectrum Pocket Book *	Toms, T
	Atom Business            *	Phipps, J
	The ZX80 Pocket Book		Toms, T
	The ZX81 Pocket Book     *	Toms, T
	Load and Go with your Dragon	Phipps J. & Toms, T.

Cassettes

	Adventures for the 48K Spectrum

		Knight's Quest
		Magic Mountain
		Pharaoh's Tomb
		Greedy Gulch

	Games for the 48K Spectrum

		Black Planet
		Gorgon

	Games for the 16K Spectrum

		Dominoes
		Rabbit Shoot
		Nowotnik Puzzle

	16K ZX81

		Knight's Quest Adventure
		Adventure Tape no.1 (containing 3 adventures)
		Dominoes
		Nowotnik Puzzle and other diversions

	* above means cassettes for the books also available

32

