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Deja Vu #08
31 мая 1999 |
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CODING - How to create uncopyable whereas sector.
AY-Track: -= 17 INSTANTS OF SPRINGS
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(C) ALLEN / XLNC.
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How to create uncopyable whereas sector
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First paragraph. Instead of joining ...
Many of us frequently encounter such
programs that are not in any copy
Xia no copiers. And this
well, since The authors of these programs
have the opportunity to dispose of
their product such as this ho
tyat they, and not Uncle Vasya barahol
ki, who is used to make
money with the help of McDonald Copy.
Do not think it wrong if I say that in every
the city has its own uncle Vasya and even without one.
And to the authors raises the question of how
would be so tricky to write to disk, what would it no one can
copy so even that it can be read.
Many authors have spit on this issue and leave everything to
chance - maybe a couple of bucks perepadet of lamers who do not
even unaware of the existence of Uncle Vasya on
flea market. Others are turning to a friend
IBM'schikam. Still others are beginning to be subverted
on the Speccy, though, everything is still on
Speccy done is copied as easily
(Remember, there were times when not everyone could copy the
IS-DOS). Of all these ways the most appropriate was the second
based on uncopyable whereas sectors. But it is associated with
drop dead expenditure of time: you can hover to run to
IBM'schiku and back home uncopyable whereas with a bunch of
disks. Well, when HRC is at home, but it's expensive, and
inconvenient.
Item Two. Closer to the case.
The article is about how you can
do uncopyable whereas sector Speccy.
To start sort out why it
Some sectors are not copied. Yes, because they can not be
formatted using standard Speccy. That is, create a title for
this sector to the SH then found it and knew where to write
data. And that can prevent you create it?
Yes, one simple fact: not all bytes are received by the data
register the SH during the recording tracks are transferred to
disc directly. There are three bayta that can not be written on
track the standard means: it
# F5, # F6, and # F7. The reason is simple: it's control codes.
(By the way, we are talking only about mode MFM. FM mode to use
is inappropriate.) Valid they only (!) Mode recording track,
ie, format. The first of these causes account code # A1 on
disk, which is part of sync, in which SH determines that Next
comes the title of the sector or the same data. But we will not
go into details. The second of these causes account code # C2 on
floppy disk, that is again harmonic registers
not what they want from it. But the most useful code - code #
F7, because it generally causes Record checksum, which is
two bytes, which usually breaks all heading. And of course,
this code # F7 on drive itself is not passed. So what happens
when the SH is trying to create on the road such sectors.
Here's what: instead of parameter (the number of the road,
head, sector, length of the sector), which recorded the number
# F5, # F6, or # F7, prescribes # A1, # C2
or checksum came bytes
that is practically a random number, and double-byte, that is,
his record demolishes even the order of numbers, and what comes
after # F7, written not in a position where it was actually the
title of full destroyed. And as the sector will have no
TE parameters, the SH does not write data from uncopyable
whereas sector anywhere, that is, if there were clues ksorki, a
copy will be at least broken. Of all of the above Private
encoder can be concluded that uncopyable whereas a sector on
the track Speccy means impossible (at
least, this idea runs through all of the text). You can, of
course, to distort and make checksum is these three numbers,
but, recognizing frankly, I do not know for sure what the
algorithm is this checksum. Especially because there is
much more simple way ...
The third point. But how?
Here's how. The numbers listed above,
can not be written on the track in all cases
except one. I do not know what caused this
effect, most likely it is some kind of flaw of the
microcontroller program VG93, but us this stuff is even on
hand. A case it is this: after writing
Checksum, SH somehow writes
to drive an absolutely any byte, including
the three ruleznyh. If you understand how to make the WG to
create a sector number (length) # F7, can stop reading. If you
have poorly understand with SH, read and memorize. For a start
tell you what is in the sector (or, rather, as his form).
# F5, # F5, # F5
# FE
CN-cylinder number. Like all the other parameters, this number
is only a formality, it does not affect the positioning of the
head during formatting, and only recorded on
drive, with all the exceptions listed above.
HN-head number. Although the range of values
this number is only a single bit, the number of
Again, you can write any, other than those
most three, and again for the second harmonic is indifferent
while formatting. SN-sector number. Everything is still the
number simply transferred to the track.
SL-length sectors. All the same, the number of
also postponed.
CC-checksum. For the record it should
once written in the data register number
# F7.
22 bytes # 4E
12 bytes # 00
3 bytes # F5
1 byte # FB
These sectors.
(Incidentally, at a reasonable question, given
some, like this: "And why, when
Restoration does not write data immediately, without a team
record sector, and during formatting? "reply to know those
who still do not understand: if the data will fall
all the same ill-fated three bytes can be written
bullshit. So, if you wish - you can
prescribe, check to see that, once ordered, are already
recording sector).
So if any of these numbers is replaced by # F7, then this
option and the next followed by replacing pseudorandom numbers
(Practice shows that they are usually alone
the same), and after them we can write _lyuboe_ number ... That
is, I do so: if when to submit cylinder number by filing
# F7. Then the cylinder number and head (hand) will replace the
random numbers. After that, I submit the following # F7, it
falls right in the place facilities sector, followed by possible
feeding the length of the sector. Attention! There is
one fine, but about her below.
That program, which rasformatit track
in accordance with the table at the end of the program.
Addresses are given for DOS v5.03/5.04
di
ld hl, # 3d98; Sub-head drags on
call dos; zero cylinder.
ld hl, # 1feb; Sub-sets of the current hand
call dos; well, which is the zero track.
; There is confusion: Zero side is
, One of which corresponds to the track
number
; One, if you count to 160.
ld a, # f4; Filing team record a track with a pause.
ld bc, # 1f;
call otac;
ld hl, tabl; Table sectors discussed below.
ld c, # 7f; Data Register VG93.
m1 ld b, # 0a; This p / n gives B B D values in the reg. C
ld d, # 4e; But in general, creates probelchik.
call l20b1;
ld b, # 0c; An array indicating Headers
ld d, 0; wok sector.
call l20b1;
ld b, 3;
ld d, # f5;
call l20b1;
ld d, # fe; This p / n produces a single byte value D.
call l20af;
ld d, (hl); Take the cylinder number from the table
call l20af
inc hl
ld d, (hl); Number of heads
call l20af
inc hl
ld d, (hl); Number sector
call l20af
inc hl
ld d, (hl); length of the sector
call l20af
ld d, # f7; header checksum.
call l20af
ld b, # 16; Space number two
ld d, # 4e
call l20b1
ld b, # 0c; Sinhropromezhutok
ld d, 0
call l20b1
ld b, 3; sync, written # A1
ld d, # f5
call l20b1
ld d, # fb; Tag Data
call l20af
ld a, (hl); Checking volume sector.
and 3; As SH programm checks for two
cp 0; bits. Incidentally, it is convenient when
jr z, k128; length of the sector, non-standard number.
cp 1;
jr z, k256;
cp 2;
jr z, k512;
k1024; So. Kilobyte sector, trivia,
ld b, 0; most importantly, what you read
ld d, 0, at the end of applets.
call l20b1;
ld b, 0;
ld d, 0;
call l20b1;
ld b, 0;
ld d, 0;
call l20b1;
ld b, 0;
ld d, 0;
call l20b1;
jr m5;
;
k128 ld b, 128
ld d, 0
call l20b1
jr m5
k256
ld b, 0
ld d, 0
call l20b1
jr m5
k512
ld b, 0
ld d, 0
call l20b1
ld b, 0
ld d, 0
call l20b1
m5
ld d, # f7; counter. sum
call l20af
ld b, # 32
ld d, # 4e
call l20b1
inc hl
ld a, (hl)
cp # ff; if not the end-repeated.
jp nz, m1;
ld b, 0, finished the end of the track,
ld d, # 4e;
call l20b1;
jp m, m2;
call l20b1;
m2
ret; exit applets.
l20b1 ld iy, # 20b1
push iy
jp # 3d2f
l20af ld iy, # 20af
push iy
jp # 3d2f
otac ld iy, # 2a53
push iy
jp # 3d2f
dos push hl
jp # 3d2f
tabl
db 0,0,1,1
db 0,0,2,1
db 0,0,3,1
db 0,0,4,1
db 0,0,5,1
db 0,0,6,1
db 0,0,7,1
db 0,0,8,1
db 0,0,9,1
db # f7, # f7, 3, # f7
db # ff
, The first number - a cylinder
And the second - head
And the third - the number of sectors,
, The fourth - the length.
Not necessarily the second (first -
- Always # F7) to make the number # F7. I prefer it, but
someone more suitable # F6 or # F5. Since the method is
described as a method, and not as an example program, which for
some reason work, do what you like.
And in the end the most important. As long uncopyable
whereas the sector is third number in line, and the fourth
should be # F7. This Several limits the programmer because
If this number is not # F7, then for some reason
data field is not. The length of such
sector will be equal to KB. If
just need to make the sector pomenee,
you'll have after formatting it to register it with zeros,
otherwise it will be of header only. The reason is that
shifting the start of the header data. If this does not
guarantee the safety sector, should be him. In short, safer to
work with the applets, so as it is written. Although an
experienced coder myself sort out my problem was only prompt
method of creating uncopyable whereas sector.
Attention! On paper there is a sign copyright
It means that everyone take advantage of my method of creating
uncopyable whereas sectors, was supposed to note this fact in a
conspicuous place where the thread in HELP'e in Credits. Since
there is another method as it turned out, he used to programmke
"Protect", placed in an annex to DEJA
VU 7, it is easy to distinguish which one is used: different
number of cylinders and hand. So, while working my utilities
that they are, respectively, # B2 and # 30. Although, if
who wants to, can not specify whose method was used, if he does
not respect copyright, and therefore the Spectrum scene.
At this point I would like to finish my articles, apologized
for the awkwardness presented and taken away for lengthy
speeches while. Hopefully, the above need at least someone.
I will be glad to answer all questions related to the Speccy.
Write to me:
454129 Chelyabinsk,
Novorossiysk,
house 93, Apt. 14
Mazyrko Boris V.
(As ALLEN / XLNC)
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