8 BIT SOFTWARE
To: CCC
From: L1M (Janny Looyenga)
Subject: REMARKS
REM" I liked this program (Issue 39)
REM" Simple and addictive - GO ON!!
REM" Now I'll never forget how
REM" I DID THIS...
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Subject: MENU (********)
A little snow in the Christmas Issue:
Very nice
<What do we get with Easter> EGGS???
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Subject: TBI-00
That's really been a job for you
Chris and quite readable, but some
people do not read very well and they
use the cursor-keys like they used to
do in Mode 7...
And what did I get... Maybe someday the pages fit too?
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From: 15A (Steven Flintham)
Subject: K8M's power supply article
Although I think I might have missed a
few jokes in this, as I'm not too
knowledgeable about electronics, I
still thought this was an entertaining
read.
From: 15A (Steven Flintham)
Subject: DFS commands article
This was very good on the whole but I
feel it was a little bit unfair to
*COMPACT. I haven't used DFS much
lately, as my BBC B is still not
working properly, but in all the time
I was using it I don't recall ever
losing a file during a *COMPACT and I
think backing the disc up before
performing a *COMPACT is perhaps a bit
over-cautious.
Having said that, I suspect that if
the disc has a bad sector on it and
*COMPACT tries to move a file onto it
then some corruption may occur (this
has never happened to me, so I may
not be correct), so I think verifying
the disc first would be a good idea.
From: K2K (Peter Davy)
Program: LOTTER3 (on Issue no.40)
This program by K8B counts up the
numbers of 1's, 2's, 3's and so on
produced as the computer repeatedly
evaluates RND(49). I cannot see what
application this has to the National
Lottery but it is an interesting thing
to do in its own right. On taking my
customary peep at the program listing
I noticed that it is quite long. I
hope K8B doesn't mind that I have
selected his program as the basis for
a short programming lesson!
All that tedious typing is a result of
using the variables Y1, Y2, Y3, etc.
in which to store how many 1's, 2's,
3's etc. have been generated. It would
have been much better to use an array
i.e. Y(1), Y(2), Y(3) etc. Lines 80 to
140, which initialise each of Y1 to
Y49 to zero would be replaced by a
simpe single line DIM Y(49). At a
stroke this would make available 49
variables all set at zero.
I am puzzled by lines 230 and 240.
RND(1) gives a random number between 0
and 0.999999999 so V will never be 1
but what does it matter as execution
will transfer to line 250 irrespective
of the value of V?
Lines 260 to 740 would be replaced by
a single line Y(X)=Y(X)+1.
Lines 750 to 810 print all 49 numbers
on the screen display but only one of
them has changed since the last time
these lines were executed. It would be
better to print only the one which has
changed.
Elsewhere on this disk is the program
MODLOT3 which incorporates the above
ideas.
Line 40 establishes the array A( ) in
which the 49 "numbers of numbers" will
be stored. I decided to display the
results in three columns to give
maximum space for each number:
1 ......26 18 ......27 35 ......25
2 ......28 19 ......29 36 ......28
3 ......27 20 ......29 37 ......25
etc. etc.
15 ......29 32 ......26 49 ......26
16 ......28 33 ......34
17 ......27 34 ......35
The top line of the above table is on
row 4 of the screen.
Line 90 prints on the screen the
numbers from 1 to 49. It uses the PROC
getxandy to find the co-ordinates for
each number printed and uses FNpad to
put a blank space in front of numbers
1 to 9. CHR$130 causes print to be in
green and CHR$135 causes the "numbers
of numbers" to be be printed in white
in due course. The main action takes
place in line 110. RND(49) is
repeatedly evaluated, the appropriate
element of the A( ) array is
incremented by 1 and this new value is
printed in the right place on the
screen using the PROC getxandy. FNpAd
is used to put dots in front of the
number to build up the total number of
characters to 8.The 4 in TAB(x+4,y) is
so that the "number of numbers" is
printed beyond the CHR$135 left by
line 90.
As would be expected the new version
runs faster than the old. On my M-128
the old program runs at about 160
values per minute while the new
version runs more than 7 times as fast
at about 1180 values per minute.
It may well be common knowledge but I
didn't know that SHIFT-CTRL provides a
temporary program execution stopper.
Thank you K8B!
To: 999 (all members)
From: K2K (Peter Davy)
Subject: 3PM's Article in Issue no.40
on the Subject of Palindromes.
Thank you 3PM for your learned
analysis of the problem of finding
palindromes which have palindromic
squares and cubes. I hope that "clear
thinking day" becomes a reality and
that you write in again with your
further deductions.
In the meantime I have been running my
program LAPPY2 on Issue 39 on my
A-3000 which is much faster than a
BBC-B or an M-128. First I ran the
program as it is to the bitter end and
showed that 2 000 1 000 2 is the
highest 9 digit number which has a
palindromic square (4 000 4 000 9 000
4 000 4). I have inserted spaces in
these numbers to make their
"palindromicity" more easily apparent.
Next I changed line no. 20 to FOR
D%=10 TO 15. The print-out showed that
2 00000000 2 is the highest ten digit
number which has a palindromic square
(4 00000000 8 00000000 4). For
palindromes up to and including ten
digits it follows that the ones which
have a palindromic square are those
which are predicted by 3PM's masterly
analysis and there are none of those
"fluke" ones.
It would have been nice to leave the
program running to find out if there
are any "flukes" with the 11, 12, 13,
14 and 15 digit palindromes. However
each time the number of digits
increases by 1 the number of
palindromes to be processed goes up by
a factor of ten and the time taken
goes up by a factor of rather more
than ten. It would have taken too
long!
As second best I have run the program
up to 14 digit palindromes but by
juggling about with lines 20, 5010 and
7010 have skipped over the ranges
where only "flukes" might exist. e.g.
for 11 digit numbers I processed
palindromes from 10000000001 to
1111111111 then skipped to 20000000002
and 20000100002 and then skipped to the
12 digit 100000000001 and so on. All
results are in accord with 3PM's
conclusions.
The highest 14 digit palindrome found
to have a palindromic square is:
2 000000000000 2, its square is:
4 000000000000 8 000000000000 4
A more interesting one is:
11 0 11 0000 11 0 11 whose square is:
121 242 121 242 484 242 121 242 121
The highest 14 digit palindrome found
to have a palindromic cube is:
11 0000000000 11 whose cube is:
1331 00000000 3993 00000000 3993
00000000 1331
Phew!
To: 999 (all members)
From: K2K (Peter Davy)
Subject: Lottery Simulation on Issue
no.40. Postscript.
I have run the program (on my A-3000
for the extra speed) on the 8 weeks
National Lottery figures 7 Jan to 25
Feb inclusive. I ran each week's
figures twice using my own and my
wife's birth dates as seeds. Usually I
ran the program to 200,000 or more
entries.
I got no match6 jackpots!
I got 2 match5+ results. The first was
on 4 Feb. (1 7 37 38 42 46 bonus 20)
using the seed 140428. The sequence 1
7 37 46 42 20 was generated as the
40,273rd. board. The second was on 25
Feb (5 8 10 18 31 33 bonus 28) using
the seed 291126. The sequence 33 5 18
10 31 28 was generated as the
281,179th. board!
Running the program brings home
forcibly to the user just how slim the
chance of winning a big prize is.
Match5, match5+ and match6 results are
so rare that it would not be sensible
to calculate the apparent odds from
the computer runs. On the other hand
match3 and match4 results are quite
common and it is interesting to
compare the apparent odds with the
theoretical figures which appear on
the How to Play leaflet.
DATE match3 match4
7 Jan 1 in 55 1 in 1006
7 Jan 1 in 57 1 in 1052
14 Jan 1 in 57 1 in 1174
14 Jan 1 in 56 1 in 1071
21 Jan 1 in 58 1 in 1045
21 Jan 1 in 58 1 in 1040
28 Jan 1 in 58 1 in 1100
28 Jan 1 in 56 1 in 1047
4 Feb 1 in 56 1 in 1044
4 Feb 1 in 56 1 in 1085
11 Feb 1 in 56 1 in 1016
11 Feb 1 in 57 1 in 1053
18 Feb 1 in 57 1 in 990
18 Feb 1 in 56 1 in 1127
25 Feb 1 in 57 1 in 1110
25 Feb 1 in 57 1 in 1154
The theoretical odds are 1 in 57 for
match3 and 1 in 1033 for match4.
It is often said that all possible
combinations of numbers stand an equal
chance of being drawn. However I'm
pretty sure that most punters would
consider an entry of 1 2 3 4 5 6 would
be money down the drain as it would be
less likely to happen. In fact 1 2 3 4
5 6 is just as likely to be a winning
entry as any other combination of
figures. You can seek confirmation of
this by running my Simulation program
and entering 1 2 3 4 5 6 as the winning
sequence and 7 as the bonus number.
You will find you do just as well with
these numbers as with numbers which
look more likely to happen.
How much real money have I risked on
the Lottery? Not a single pound!
From: K2F (John Davis)
Program: Lotter3
Wow! Forty-nine consecutive IF
statements in Andy Brandon's lottery
program in issue 40. These can all be
eliminated by putting each new number
in an array:
DIMA%(49)
R%=RND(49):A%(R%)=A%(R%)+1
Then, more interestingly, instead of
reprinting all the numbers each time,
just the new number can be printed,
calculating its screen position from
its array number (R%):
PRINT TAB(((R%-1)MOD7)*4,((R%-1)DIV7)*
3+1);A%(R%)
This saves a lot of effort, and the
program will also now run fifteen times
quicker.
From: 20G (Roy Dickens)
Subject: A FEW COMMENTS
8-Bit intro. screens
Our Ed. Chris reckons that we should
have some more intro screens. I agree
with him. How about having a look at
the (now PD)'Acorn User' intro screens
for a few ideas. Or juggle them about a
bit and use them. I suppose its OK now
they are PD. The two that I put in was
only Mode 7 with a bit of teletext
graphics and bit of scrolling. OK it
wasn't much but it was fun doing it
and I got a prize!
Lotter5 by Peter Davy (K2K)
This was a very informative lottery
program. I have not had a go on the
lottery yet and after Peters progam I
don't think I will!
Dominoes by Stuart Angell (K8F)
I have seen this type of program with
snakes and caterpillars but it makes a
nice change using dominoes.
Membership List (Chris)
Thanks for the membership list Chris.
Very handy to check the ID. It looks
a long list. I hope that they all send
their fifty pence etc. every month to
keep you nice and busy.
From: K6X (Cluke)
Subject: Digipics
The cheetahs were superb on screen,
the b/w version looking great when
viewed from near or far, the colour
version needing to be viewed from a
distance to get the colours to blend
to best effect. Only niggle is that I
have not been able to get a decent b/w
printout that does not reverse black
for white, and distort the image
making it narrower and longer. Has
anyone managed to print it out so it
looks good? If so PLEASE, PLEASE tell
me how?
BLAM!