Spider webs by natural selection

I recently discovered this awesome BBC BASIC program for simulating spider webs through natural selection. It was written by Matthew Tizard for the BBC Acorn User magazine October 1992.

Natural selection left running on a BBC Master 128 for a couple of days.

The program generates nine 'spider webs'. The fittest spider web is the web that catches the most 'flies'.  This web is then chosen to go into the next generation.

Natural selection running on BeebEm with 6502 Second processor showing nine generations with 'flies' turned off.

I found that the program is best run with your second processor turned on (for hopefully obvious reasons). In fact I found that you get approximately three times improvement in speed, with one generation taking about twenty seconds to generate, draw and test on screen.

You can easily switch on your second processor using BeebEm as shown above.

Another version of the program allows you to control evolution by choosing which web you wish to survive into the next generation. In this way you can select for characteristics that you like, not necessarily the ones that will catch the most flies.

Assuming that the program is in the public domain I have put the files onto a BBC disk image which you can download from the link below.
BBC Disk Image

You will need to load the disk image into your emulator program, or directly into your microcomputer using the datacenter, MMC unit or otherwise copy it onto a floppy disk.

There is a readme file which can be loaded with *type T.readme

The programs can be executed with CHAIN "ArtAuto" OR CHAIN "ArtLife".  Press <ESCAPE> and type LIST to see the program code.

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+1 Geek Experience point for Matthew Tizard

#geek #bbcmicro #naturalselection #spiderwebs

Assembly language hacked by 14-year-olds

The following two programs are very impressive examples of independent work produced by two 14-year-old boys using my Little Man Computer simulator.

The first one by Eric is an integer division program that can deal with both negative and positive integers and which returns both the whole number division and the remainder.  The second program, written by Will, is a general purpose calculator that can deal with addition, subtraction, multiplication, integer division, square roots and raising one number to power.

Not bad stuff for a program that can only ADD and SUBTRACT(!)

Eric's division program first.  Enter two numbers X and Y respectively and the program calculates X DIV Y and X MOD Y.

#DIVISION with remainders and negatives!

#By Eric

.

INP

STA TOP #Input the top part of the fraction, e.g. [8]/3

BRZ TOPZERO #If top zero simulate input and then

#output 0

INP

BRZ HALT #If zero, just go. DIVBYZERO

STA BOTTOM #Input the bottom part of the

#fraction, e.g. 8/[3]

BRA NCHKO

.

TOPZERO INP #sim input

LDA SWAP #load swap (0 by now)

OUT #outputs it

HLT #and stops!

.

NCHKO BRP NCHKT #check bottom for efficiency

SUB BOTTOM #use clever maths to realize that x-(x-x) = -x

SUB BOTTOM #if the numbers weren't positive it would

STA BOTTOM #mess the program up

LDA MINUSONE #negmult is now -1, so it's negative

STA NEGMULT

BRA NCHKT

.

NCHKT LDA TOP #check top now

BRP START #if not negative just go to setup

SUB TOP #same clever maths as before

SUB TOP

STA TOP

LDA NEGMULT #loads the negative multiplier

SUB NEGMULT

SUB NEGMULT

STA NEGMULT

#and uses SAME clever maths trick to invert, again

LDA TOP

BRA START

.

.

.

START SUB BOTTOM

#alright so I better explain

#the thing is that the way I divide is:

#I count how many times I subtract the bottom from the top

#When the top is negative it checks for a remainder

#by adding the bottom on again

#that is the remainder

#so example:

#14/3 - it subtracts 3 from 14 5 times

#and then adds 3 again, takes one away from the

#5 times (makes it 4) and the remainder is the result after

#adding 3. 4r2 which is the correct answer.

BRP NFINISH #if positive NotFINISHed

BRA FINISHUP#else finish all things up

NFINISH STA SWAP #stores current result in swap

LDA RESULT #loads the result

ADD ONE #increments

STA RESULT #stores result

LDA SWAP

BRA START #loads swap and removes and starts again

.

.

.

FINISHUP ADD BOTTOM #adds bottom to figure out remainder

STA REMAINDER #stores that as remainder

LDA NEGMULT #remember this?

BRP OUTPUT #if negmult is normal just output

LDA RESULT

SUB RESULT #else use my favourite maths trick

SUB RESULT

STA RESULT

OUTPUT LDA RESULT #easy peasy

OUT #output result

LDA REMAINDER

OUT #remainder

HALT HLT #cya 

#Variables

NEGMULT DAT 1 #Negative multiplier

MINUSONE DAT -1 #-1 [CONST]

ONE DAT 1 #1 [CONST]

TOP DAT 0 #The top part of fraction

BOTTOM DAT 0 #Botttom part

RESULT DAT 0 #Result

REMAI DAT 0 #Remainder

SWAP DAT 0

#Swap data used by program for general stuff

Here is Will's general purpose calculator.  The first number input is the menu option:
0: for square root
2: for division
3: for subtraction
4: for addition
5: for powers
6: for multiplication

#Will
#A general purpose calculator which works with the limitations of the little man computer

#

INP # Press zero for square root, two for divide, three for subtract, four for addition and five for power, six for multiply

STA D

INP #Enter the first number, this is the number that all the functions will be done to

STA A

INP #With square and power, due to limitations of little man computer size, does nothing but is the operating number

STA B

LDA D

BRZ SQUARE #Go to square function

SUB ONE

BRZ DIVIDE #Go to multiply function

SUB ONE

BRZ SUBTRACT #Go to subract function

SUB TWO

BRZ ADDITION #Go to addition function

SUB ONE

BRZ POWER #Go to Power

LDA B #Multiply Function

SUB ONE

STA B

LOOP LDA C

ADD A

STA C

LDA B

SUB ONE

STA B

BRP LOOP

LDA C

OUT

HLT

DIVIDE LDA A #Divide function

STA A

LOOPD LDA COUNT

ADD ONE

STA COUNT

LDA A

SUB B

STA A

BRZ ZERO

BRP LOOPD

ZERO LDA COUNT

OUT

HLT

ADDITION LDA A #Addition Function

ADD B

OUT

HLT

SUBTRACT LDA A #Subtract Function

SUB B

OUT

HLT

SQUARE LDA A #Square root function

STA A

LOOPS LDA COUNT

ADD ONE

STA COUNT

LDA A

SUB X

STA A

LDA X

ADD TWO

STA X

LDA A

BRP LOOPS

LDA COUNT

SUB ONE

OUT

HLT

POWER LDA A #Power function

STA COUNT

LDA COUNT

SUB ONE

STA COUNT

LOOPP LDA COUNT

SUB ONE

STA COUNT

LDA RESULT

ADD A

STA RESULT

LDA COUNT

BRP LOOPP

LDA RESULT

OUT

HLT

A DAT

B DAT

C DAT 000

COUNT DAT

X DAT 001

ONE DAT 001

TWO DAT 002

RESULT DAT

Circles

Circles is a program to aid independent learning in mathematics.

Circles was written for Mr Bakr Al Bazi, Mathematics teacher at the Grammar School at Leeds, who writes:

"3 circles, 6 values for each circle. Students started to investigate these values with no input from me."

"Independent Learning was taking place. Ratio, radius, diameter.... every notion that involved circles was discussed and then pi came in." 

"It was wonderful! I realised that adopting the use of new technology to support traditional instructions has not only it made me change the way I teach, but also the way students learn." 

Follow this link to continue to the Downloads page.