COMPUTER BITS
By JENNIFER BONNITCHA
Setting up your hard disc
Enough is enough. The time has come! For what
seems the hundredth time, you swap your program
and data discs to continue working. While waiting
for the files to load from disc, you ponder the
possibility of finally taking the plunge and buying a
hard disc.
Alternatively, you could be a victim of the dreaded "1701 Error No
Boot Device Available" - your
whole life flashes before you as,
with growing dread, you search for
the last set of backup discs.
The PC hard disc is a typical
"black box" where a light blinks
when you put data in and when you
get it out again. As noted last
month, hard discs store much
larger amounts of data and access
it faster than floppy discs. They
have been available for about as
long as the PC has been around.
However, it wasn't until the introduction of the XT computer from
IBM that the hard disc was offered
as a feature.
Increased storage capacity and a
considerable reduction in the time
required to read or write data
means that the hard disc has
become almost essential for even
This DC-2200 hard disc controller card from Electronic Solutions will work
with older IBM PC/XTs or compatibles, as well as with the newer turbo XT
machines. It is installed in a vacant expansion slot on the motherboard.
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SILICON CHIP
the generally conservative computer user.
And now you have decided to join
that group. However, before you
can utilize all those megabytes, you
need to install the hard disc - and
that can be a daunting experience
for many users.
Finally all those megabytes are at
your fingertips and the moment has
arrived to tackle the installation.
Make sure you have plenty of time
to spare so you don't have to rush
through the procedure. A good start
is to turn the radio or stereo on,
select a soothing tune, then begin.
Opening the case
Have close at hand an assortment of screwdrivers, your computer's reference manual and the
new hard disc. Disconnect the
keyboard and ensure the system
power unit switch is off. Disconnect
the power cord from the wall outlet
for added security.
Now either place the system unit
on a suitable table or turn it around
to allow easy access to the rear
cover mounting screws (generally
anything from two to five screws),
and arm yourself with the appropriate screwdriver. Fig.1 shows
the locations of the cover mounting
screws for an IBM-style case.
Remove the screws, set them
aside, then slide the system unit
cover from the rear and toward the
front as illustrated in Fig.2. Finally,
when the cover will move no further forward, tilt it at a 15° angle
and remove it from the base as
shown in Fig.3.
So far , so good. Set the cover to
one side with the cover mounting
screws and examine the inside of
the system unit. The power supply
amount of memory or the presence
of a maths co-processor - are installed or connected to the PC.
Fig.1: here are the locations of
the cover screws for an IBMstyle case.
Hard disc controller
Fig.2: remove the screws, then
slide the cover forwards as
far as it will go.
1/
Fig.3: the cover is removed
from the base by tilting it
upwards at a 15° angle.
in an XT is located in the same posi-
tion as the PC power supply at the
top right of the system unit. The
lower left section of the XT contains sockets for memory chip installation, while a single configuration switch containing eight DIP
(Dual In-line Package) switches is
located below and to the right of the
system expansion slots (the PC has
two 8-position switches).
These switches, shown in Figs.4
and 5, define which options - such
as the number of disc drives, the
The hard disc itself is just a
recording device so a hard disc controller (in conjunction with the
operating system) is required to
determine what the disc actually
receives, how fast and where it will
be placed. The hard disc controller
handles a multitude of tasks: formatting the disc for later use, encoding the data it receives from
DOS, instructing the hard disc
where to place the read/write
heads, writing, reading and verifying the data, correcting errors and
reporting back to DOS with the
data and status concerning success
or failure.
Install the controller card in one
of the vacant expansion slots (it
doesn't matter which one) and connect the signal and power cables.
Mount the hard disc as required in
your system unit, then connect the
cables. Once all the options are installed in the system unit, make
sure the appropriate DIP switches
are set to reflect the current state
of your computer.
Caution here! The functions of
the DIP switches shown in Fig.4 are
for one model of the IBM PC and
there are differences between
models. You should read your computer's reference manual very
carefully to ascertain the correct
settings of the DIP switches for
your machine.
Make sure you note the position
of all DIP switches before you
begin. Fig.5 shows the DIP switch
settings for the PC XT. You may
find your compatible does not have
as many switches.
Before leaving the factory, the
hard disc is erased so that it contains no information at all. The disc
manufacturer has no way of knowing what type of disc controller will
be used with the disc and while the
connector that attaches the drive to
the controller is standard, the way
controllers encode data isn't.
Low level format
Once the disc is installed, it is a
good idea to perform a system
checkout using your computer's
Diagnostic Diskette. This disc also
OCT0BER1989
77
Switch 2
Switch l
2
01
3
4
5
6
7
8
~□~□□□□□□
Position
1 7-8
2
34
5-6
Function
SYSTEM
BOARD
Switch I
l6Kl310
32KB
48KB
6
41
<0
Switch 2
□□ □ 00001 I □ □□□ 00001
l□□□□ oo□□ l l□□□□oo□ol
I□ on 00000 I l□□□□ooo □I
I□ LIU □DODD 11 □ □a □ ODO DI
MEMORY
OPTIONS
96
KB
Position
100□□ 00001 1 □□□□00001
l□□□□□o □□ I l □□□□boo □I
I6
100□□ 000011 □□□□ 00001
196KB 1□ 0 □□00001 1□□□□00 □□1
228
100□□ 00001 1 □□□□ 00001
Amount of memory options installed
Always in the off position
Number of 5-1/4" diskette drives installed
Switch I
Switch 2
0-Drives
l □ oooo□a□ I l□ aooo□ oo I
I-Drive
1000000□□ 1100000000 I
2-Drives
l□□oooo□□ l l□□ooooo□ I
Monitor type
Switch I
No monitors
128KB
40 x 25 Color
0KB
80 x 25 Color
I
Switch 2
I00000000 IOOOOOOOO
I
IO000 □□ 00 IIO0000000 I
I0000 □□ 00110 00000 00 I
Note: The 80 x 25 color setting. when used with
home television and various monitors can cause
loss of character/quality.
10000□□001 l □□oomrn□ I
KB
256l~Bl□ ouuououl l □□□ auo □□I
Function
1-2-3-4
5-6- 7-8
Number of 5¼-inch diskette drives installed
Reserved for co-processor
Amount of RAM on system board
Type of monitor you are using
IBM Monochrome
Display or more
than one monitor
Fig.4: this diagram shows how the DIP switches are set to select the memory,
drive & monitor options for one particular model IBM PC. Check the manual
for your particular machine carefully as there are differences between
models. Note that Switch 1 selects the number of floppy disc drives only.
contains the low-level format information. For many computer users,
the low-level format is never seen
as the dealer takes care of this
basic but very important step.
However, it is a very important process which can affect future
performance.
The low-level format is performed using the manufacturer's disc
diagnostics, or a program built into
the disc controller and accessed
generally through the DOS command Debug.
78
SILICON CHIP
Your computer is capable of running UNIX, XENIX, PICK, CP/M-86 or
OS/2. All it needs is an entry to the
MBR (Master Boot Record) indicating where the operating
system begins on the disc, how
much space it takes, whether it is
currently active and a unique
character for future identification.
The format program instructs the
controller to format the disc one
surface at a time, dividing up each
side of each platter into concentric
rings, or tracks, and breaking each
ring into manageable pieces
(sectors).
Each sector begins with a distinctive data pattern to help the disc
controller determine the sector's
start position. Most hard discs are
formatted with 17 sectors per track
and each sector contains 512 bytes
of information. The newer IBM PS/2
series computers support larger
sectors, commonly as many as 37
per track.
The controller level format performs two other functions. First, it
sets the interleave (the sequence in
which sectors on a hard disc are
organised). Second, every sector on
the disc is tested for its ability to
record and store data. Sectors
which fail this test will give errors
and can be locked out by the controller to ensure that DOS never
tries to store data in that sector.
FDISK
Once all sides of all platters are
formatted and the bad track information entered, the disc is ready
for the FDISK program which
creates the Master Boot Record
(MBR) on track 0, head 0. Boot your
computer from Drive A using your
DOS disc. When you use FDISK, it is
a good idea to view the partition information before you go any further
to see the current status of the disc.
Type FDISK then press (Enter) to
display the main menu of the FDISK
program. The options include:
(1). Create DOS Partition
(2). Change Active Partition
(3). Delete DOS Partition
(4). Display Partition Data
If you had installed two hard
discs, a fifth choice permitting you
to select the next hard disc drive
would display.
Select Option 1 so you can create
Switch
I
2
3
4
5
6
7
Fig.5: XT machines have a
single configuration switch
located below and to the
right of the system expansion
slots. Positions 7 & 8 select
the number of floppy disc
drives installed.
8
of~~ □□□□□□
Position
2
3-4
5-6
7-8
Function
For normal operation is off
Co-processor
Amount of r~AM on system board
lype of monitor you are using
Number of 5¼-inch diskette drives installed
Memory options
128K
192
K
2551
\
l □□□ UUUUUI
Ioo□ uoouo I
Without co-processor
1 Drive
IDDOOO ODQI
2 Drives
IOaOLI OOu□ I
Monitor type
Co -processor
With co-processor
Root directory
Number of 5¼-inch diskette drives installed
I□ a□□ oooo I
IO OOOOOOI
IO~ 0000 OI
O
LJ
No display
1 □ 000000 □1
IBM Coler Display or other
color display in the 40 x 25
Coler mode
1 0000 □□0~1
IBM Color Display or other
color display in the 80 x 25
Color mode
1000 □□□0 □1
I_ODO O□ noW n1LI _
IBM Monochrome Display or
more than one display
a DOS partition and decide how to
split your disc. Note that you can
have partitions other than DOS on
the disc (when running UNIX for example) and that DOS won't touch
the MBR entries for these other
systems. Decide whether or not you
want to use the entire hard disc for
DOS and continue. Note that some
versions of FDISK don't automatically activate the partition so you may
need to choose Option 2. Review the
partition data before you exit
FDISK.
Using FORMAT
Once the DOS partition is
created and activated, you must
format the disc as final preparation
for use. To do this, you use the
familiar DOS program FORMAT.
This program makes the DOS partition usable by establishing the DOS
Boot Sector, a File Allocation Table
disc to show what area the file occupies on the disc and where the
next piece of data, if applicable,
can be found.
The FAT functions in much the
same way as the table of contents in
a book. DOS generally maintains
two copies of the FAT so that if one
is damaged, it can use the other.
However, it can't decide which is
correct if there is a conflict.
(FAT) and an empty Root Directory.
The DOS Boot Sector is what the
Master Boot Record helps point the
computer to when you turn on the
power or perform a system reset. It
is actually a small program containing some important pieces of data
specific to DOS such as how big the
boot sector is, how many FATs and
their size, the size of data clusters,
the size of the root directory and
what the system files are called.
Disc structure
Without a valid DOS Boot Sector,
the computer usually freezes or
may boot straight to BASIC (on IBM
PCs which have BASIC in ROM).
Right after the Boot Sector comes
the first copy of the File Allocation
Table (FAT). The FAT has one entry
for every place on the disc where
data can be stored. The table is updated each time a file is written to
Finally, after the second copy of
the FAT comes the Root Directory
which is the main directory from
which all others branch. Unlike
other directories, it is fixed in
length and typically contains a
maximum of 512 entries (although
larger discs may hold 1024 entries).
Following the root directory, data
storage commences and extends to
the end of the partition.
Typical Format options include:
FORMAT C :/S/V the /S
parameter causes the transfer of
system files like IQ.SYS, DOS.SYS and
COMMAND.COM from the DOS disc
to the hard disc. The two SYS files
are hidden from view to prevent accidental erasure and are only
reported when the CHKDSK program
is run.
Using DOS version 3.X, the program issues a warning before it
commences formatting the hard
disc . Previous versions simply
issued the standard message and
commenced formatting immediately. Since you want to format the
new DOS partition, you would respond in the affirmative. After
several minutes, the messages
"Format Complete" and "System
Transferred" will be displayed
because you included the /S option.
Next you will be asked to enter a
label for the disc. This label is optional and has no real significance
for the computer's operation.
A new life
Once you have partitioned and
formatted your hard disc you are
ready to copy DOS to the DOS
directory on Drive C and begin a
whole new life as a computer user.
The system will now automatically
recognise that your computer has a
hard disc and you can now boot
programs directly from it.
~
OCT0BER1989
79
