Commodore Free 21/Commodore_Free_Issue_21_2008_Commodore_Computer_Club.d64/t.b guide 6.2

Text File | 2023-02-26 | 13KB | 406 lines

u
In the Beginning Part 6
\Lord Ronin from Q-Link\

 Chapter 6, Section 2

 Back to the only one sided notched.
If you have a 1571 in your collection.
Take the disk directory and add it up.
Add to that the blocks free, and
subtract it from 1328. Should get a 0
if it is a 1571 formatted disk. If so,
put it off to the side for now.

 However if you don't have a 1571
drive and you have single notched
disks. These disks are tested and are
not what you would think as factory
disks of some sort. Yes feel free to
load them up and see what is there. As
I said some factory disk games use the
reverse side for the data. But you
can't write or save to that side. Have
to turn the disk over. If that isn't
the case. Then you have a disk that
has a virgin side. The previous owner
didn't notch it and it hasnever been
used.

 But how to notch it? Well the easiest
is a disk notcher. Which you may have
in the box of stuff. Take a look, it
is in different forms. But the basics
are the same. On the top is a push
button about thumb size. Along one
side is a long slot. If you find that
sort of thing, plastic or metal, I
have both. Then you probably have a
disk notcher. Why didn't the guy notch
the disk? Well disks didn't come
double notched for the most part. You
do a hundred or even ten at a time,
and you will see why. I did over a
dozen each month for the users group.
Hated that task. Ones hand gets very
sore. Anyway, if you have one. Just
slide the non notched side into that
slot.

Get it in tight both to the inside and
to the top of the notcher. Then press
down on the spring loaded button. Hey
if it feels like they put in a truck
coil for that spring. You have the
same type as I started with at my
beginning. Well now if things worked
out. You will have a bit of the
plastic jacket come out the bottom.
Safety note, grab that and toss it
away if you have pets or small kids.
The notch should be as deep and
exactly at the same level as the
original one. Just on the other edge
of the disk. OK I admit that there are
times that I don't get it just right.
So back in the notcher it goes.

 What if you don't have a notcher? A
reason why the disks in your
collection may all be just one sided
used. Some users didn't know that they
could notch the disk and use the other
side. But if you see disks, looking at
the top or label side that have a
weird sideways V cut. Or a half round
cut. The previous owner used the
cheaper and more dangerous method of
disk notching. I would suggest hunting
around on the web, the net and locally
to find one laying about. A disk
notcher I mean.


 But failing that task and wanting to
get to the C= right now. Here is what
you do, and it is dangerous to the
disk. You can use either a pair of
scissors, that is the style that makes
the sideways V cut. Also the most
dangerous of the two methods. Or you
can use a paper hole punch. That is
what made the half circle looking
notch. I met one guy that was expert
enough to use an exacto knife. I don't
suggest that one unless you have good
eyes and very steady hands. I fit
neither of those classifications.


 Most people would take the sleeve,
that is the paper holder for the disk.
Line it up level with the existing
notch. Then carefully clip with either
of the above tools a little notch on
the side. Sounds easy? Well here is
the problem. Inside that disk jacket,
the plastic part, is the round
magnetic media. Clip that and the disk
is trash for the most part. OK
depending on how much is on the disk.
You may be able to save the files to
another disk. But don't risk it. If
you have to use this method. Well you
can see the depth of the factory
notch. Go less than that to be safe.
Or the disk is fairly well ruined.

 That all being said in as much depth
and warning as possible. Time to
format the disk. Despite any fast
loader carts or jiffy dos. We are
going to do it this way.

open15,8,15,"n0:disk name,**":close15

 OK in as little technical talk as
possible. You are opening a
communications path to the disk drive.
That is the 8 part. The 15 and there
are two of them there, well it is
complicated and to be as brief as
possible. This is the channel to send
and to receive information from the
disk drive. I use 15 as it is common
and 15 is the one that will send back
any error. OK you can use up to 255 as
the channel number as that is how many
there are from what I have been told.
Gotta have those commas for the pause
direction thinggy. Don't worry about
that part.

Just copy that into your format line.
Quotes are needed to set up what you
are going to do, yeah sort of like the
print statement. Now the N0: part is
for formatting the disk. The command
to format. Disk name is what ever you
want up to 16 characters and yes you
can use spaces. Those two ** things,
are to represent the two characters
from the KB that you use to
specifically code this disk. End the
command with the close of the quotes.
Thsymbol separates commands on a line.
Since we opened 15 now we have to
close 15.

 Enough technical talk. Really won't
mean a lot to you till much later on.
Sort of a little teeny bit of ground
work on some techy stuff. After you
typed open15,8,15,"n0:disk
name,**":close15 Press return and you
will hear the disk drive rumble, grunt
and perhaps even make a grinding
rattling noise. Light may flash
rapidly, causing you to worry that you
did something  wrong. That is the head
setting up for the formatting. All
that track and half track with sector
stuff. Not time to go into that stuff.
Head just has to go into the right
place.

 May hear a clicking noise coming from
the drive. That is the head moving one
track at a time out of the 35. Drive
will eventually stop. Green light will
be out and the READY will be on the
screen with the flashing cursor. Well
if everything goes right. There can be
some problems and that is another
section to deal with for more advanced
beginning. Suffice it that if the
stuff written above doesn't happen.
You got a bad disk or drive. Sorry but
that part is for later on in the
series.

 Check the directory to see if it did
format correctly. Did you get the name
and ID code right? Probably, but there
could be another problem. I have had
to do the format more than once on the
same disk side. Not because I did
anything wrong. Just that disks that
are 10 years and older. That haven't
been used, like that side 2 part. Need
to be formatted 3 or 4 times.

What happens is that it stops during
the format. Either the clicking of the
head movement stops real fast. There
is almost a lort of purr like noise at
the end of a format, at least on my
system. OR the click starts at the
steady rate and then slows down.
Exactly why, I don't know, just pass
it along that the disk can be set in
its ways and needs to be hit a few
times with the format command to work.

 Might get to this again later. But
for right now, here are some other
commands. To save space, my fingers
and your eyes. Lets just go with it
stated that each of these needs the
open15,8,15, part and after the quotes
the :close15 part. OK you can be short
and use oP in lower case to open and
cL to close.

"s0:filename" This will scratch the
name of the file you select. Scratch
means that it isn't on the directory
anymore. But it is still physically on
the disk. Until you either record some
other programme thing over it or

"v0:" and that is validate. Closest to
that on other platforms is defrag, or
so I have been told. Don't have any
experience. Validate picks up the bits
and in a simple term, tightens up the
disk space. One book I read said to
validate after every three scratches.
I don't as a rule myself. More like 5
or 8. This moves stuff around on the
disk. Which will destroy the scratched
files. Right the feds can't read the
disk. <SEG>

"n0:filename" No this isn't format.
There isn't the 2 character id code.
This is new the disk. Basically it
just erases the directory. Sort of
tear out the table of contents for a
book. Files are still there and with
tools can be recovered. A fast format
way that has some drawbacks and I know
long time crackers that won't use this
command.

"i0:" Initialise the disk. Some books
say to do this every time you put
another disk in the drive. Main reason
is that if there is a chance that the
id code of one disk is the same as
another disk. Well the computer will
work as if it is the same disk. At
least in the BAM, or Block
Availibility Map. I have also seen it
as Block Allocation Map. In short that
is the disk roadmap where things are
located on the disk. Hard to drive in
Liverpool England, if you are using a
Portland Oregon Map. In the computer
case the result can be. You write over
things on the disk. Because the old
map said it was empty.

 Lets say that after all of that dull
stuff. You have a disk that is ready
and we are going back to the Variable
thing now. V V% V$ are the three
types. Yeah I know they just love to
use X in the examples. But I am
antiestablishment.

 V% give the whole number. V gives the
number with decimals and V$ is for
printing text. Well there are 26
letters and 10 numbers that you can
use for variable names. Meaning that
you have 36 possibilities for a
variable? Well I cheat and programme
in lower case. Using Upper case
characters as well. Tip here is that
not all upper case work that way.
Still not to worry. 36 is a big
number. Well it gets bigger. You see
the book takes time to bring his up.
But you are not limited to V$. Nope
you can have V1$-V0$ as well as
VA$-VZ$ 26 letters and 10 numbers,
that you can use singly and in two
characters for your variable. Makes
that number a bit higher. Though a bit
early in this drivel. Variables can
also be reused in programmes. We, OK I
am not ready to go into that at this
time. Lets end this part with the
understanding that when you change the
value of a variable. The new one
completely takes over the old value.
Book says it with the example

X=X+1.

 Next comes the IF THEN statement.
Simply put. IF this part is true THEN
go to this. Conditioner thing for the
programme. Book gives the following
thing to type in.

new <type in and press return. Clears
the memory for you of anything left
behind. Additive: most of the time>

10ct=0
20?"commodore 64"
30ct=ct+1
40if ct<5then20
50end

 Remember to press return at the endof
each line. A common fault in doing
type ins is forgetting that keypress.I
am very guilty of that. Now type rU
and see what happens.

 You get the word printed out 5 times.
Lets figure out why. Well the secret
is in line 10. Here you see a two
character variable called ct. Think of
that as a short form of "CounT". This
is set by the "=" sign to be at 0.
Next line is the stock print
statement. Telling the computer what
we want to print. Now we have that
"ct" again. This time it is set to add
1 to the value of ct. Seeing how a
variable can be used more than once.
40 asks the question is ct less than
5. If so then go back to line 20.
Which is the print line and we keep
going around till ct is 5. At that
point the programme moves to the next
line, which is end and that shuts off
the prg.

 Book doesn't go any farther in a use
of IF THEN. Well it is written for the
first timer. I use it in some of my
work to send the programme to a
specific area. IF certain conditions
are met. THEN it goes to that area of
the programme. One that comes to my
mind is a programme I wrote for AD&D
experience point calculations. Merely
took the data from the book and made
it a programme. There are over 10
basic things for the start. These are
the Hit Die of the monster. IF HD=8
THEN 300, is sort of the line that I
wrote. User had to type in the HD
value. That became the variable and
the math started for the calculations
on that specific line. Have seen a lot
of simple menu programmes that use the
same IF THEN style to load programmes.

 At this point you may want to save
the little prg to disk. we did the
tape one earlier. On a blank line type

save"name file",8 <press return> Give
it what ever name you want, and it
should be making the disk spin and you
will in a short time see that ready
and cursor flashing again.

 So there are some weird things to use
in a programme. I mean like that "<"
thing above. Here is a chart of them
and what they mean.

<     less than
>     greater than
=     equal to
<>    not equal to
>=    greater than or equal to
<=    less than or equal to


 Not a great help at this time.
Something for future reference.

 That is followed by the FOR NEXT
LOOPS. But that and the example will
be in the next part. Out of space
again. Talk too much I guess <BG>