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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. 76 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