The structure of hard disk partitioning
Scorpion on a computer
Vlad Sotnikov (Vega)
The system MS-DOS program for the spectrum
ma, of course, to work without a definite and
very time-consuming adaptation can not. Tre
retical create on the hard disk system
TR-DOS. The authors of the Shadow Monitor approached
solve this problem quite original
but: on the hard drive creates a sequence
sequence TR-DOS disk images, and each of
these images can be "connected" to the carrier
telyu A, B, C or D, and the operating system
TR-DOS will work with this way, not
suspecting that this is not a real disk. Whence
so is the terminology: the physical disk (flexible
cue a floppy disk) and the emulated drive (HDD
image).
File structure Winchester
Structural organization of accommodation on
hard drive information is as follows
manner.
1. Will create a global sub-wearing
schy always the name of the MFS (MOA FileSystem?).
Shadow monitor will only work with
him. In addition to this subsection on a hard di
skeleton may be other sub-
operating systems. Thus, one
HDD can be used on Spec
Truman, as well as on other computers.
2. Within the global sub-create
tsya so-called local sections.
They may be the following:
- TR-DOS. This section contains a cross
Be the sequence of TR-DOS image dis
orders (from 1 to 51).
- MicroDos. As the author wrote of the Shadow
Monitor this subsection is reserved for
compatibility with PCs, using Linux,
and software support of this subsection
planned to write in the future. But
so far so nothing is written
and it was not.
- IS-DOS. Subdivision for OS odnoimen
nym name.
- BAD. With the help of this subsection to
Winchester covers an area that has
bad sectors.
Ways to work with this structure, wine
Chester through the menu of the Monitor and the Shadow
subroutine RST 8 are quite diverse.
Here I will describe how this
structure looks like from the inside. "
Subsections describe the structure
List of sub-global is
in the 0-th relative sector (0 cylinder, 0
head, 1 sector) at # 01BE and occupy
maet 16 bytes, where:
0 - At MOA 0.
1 - head |
2 - Sector | beginning
3 - cylinder (?) | Subdivision.
4 - at MOA # 53 - MFS.
5 -?
6 -?
7 -?
+8 |
+9 | Relative address
+10 | Subdivision.
+11 |
+12 |
+13 | Length sub
+14 | (In sectors).
+15 |
Total number of such descriptors can be 4.
Fourth byte # 53 - a sign of sub-
MFS. The meaning of 5,6 and 7 of the byte I guess so
and failed. Also, I'm not quite sure
value of the third bayta.Tem least ,2-nd and 3 rd
bytes indicate where the list of locally
locally subsections.
It takes 2 sector (1024 bytes). Opi
description of each sub-section is 16 bytes
and is as follows.
0 - type of sub-section:
1 - TR-DOS.
2 - MicroDos.
3 - Is-DOS.
4 - BAD.
+1 |
+2 | Relative address
+3 | Subdivision.
+4 |
+6 |
+7 | Length sub
+8 | (In sectors).
+9 |
10 - Name of sub-section (6 characters).
With the 4-byte relative hell
rez, we can turn to the top of any
Local subkey.
The internal structure of sub-
Subsections MicroDos and BAD internal
structures do not have. Subdivision IS-DOS such
structure has, but she is determined goals
com and complete only the operating
system.
Structure of the sub-TR-DOS
Now consider the sub-TR-DOS. He
is one of the central sub-
on the hard drive, as most prog
Ramm work with this operating
system. Therefore, we consider it Naib
more detail. Structure of the sub is as follows:
in the first two sectors is a description of
TR-DOS disk images. Description absolutely
similar in structure to the description of locally
locally discs. Each disc is described 16 buy
coefficients, where 0 - is always 1 (TR-DOS), +1 - Hell
res disk image, plus 1, 6 - Length CD
(Always 1,5,0,0 - because the length of TR-DOS
form a strictly fixed: 1280 a 512-buy
tnyh sectors), 10 - the name of the disk. Standard
Noe the name - "Disk??", where "?" - Index
number of the disk, but it can be painless for the
Shadow Monitor change.
Please note that the address on the disk
hard drive to add 1 sector.
The fact is that before each disc misunderstood
TNO why there is a 512-byte area
filled with zeros.
I also want to draw attention to the maximum
mally allowable number of discrete images
Cove in TR-DOS section. I've
an opinion that there may be more
than 51. Explain what is confusing:
The fact that the Shadow Monitor for the Treatment
of the disks within the subsection uses
16-bit register. With respect to the
sub-address 51-second drive to be # FF33,
and address of the 52-second drive would be # 010434. It
Therefore, the maximum number of drives in
subsection - 51.
