Ferguson Institute Online Div. of Jmlit
Computer Techology Department

Assignment #1a
THE MAIN CHIPS ON THE MOTHERBOARD:

CPU:  The main microprocessor "chip" that decodes & executes computer program instructions.  It has pins on it for connection to the address bus, the data bus, the control bus,  the power supply and the crystal controlled timer , thats used to clock instruction sequences.  

BIOS:  The BIOS chip is the main ROM (read only memory) chip that stores system program routines, mainly for basic input/output functions,  and startup diagnostic programs including  the setup program.  Depending upon the PC model, hit the F2,F5, or "delete" during startup to start the setup program.  Once you have entered the setup program make adjustments to items like the startup sequence, harddrive parameters, and other configuration changes.  The setup program in ROM memory is permanent and cannot be erased by normal means.  Programs and data are burned into these chips and remains in the chip even after the power is turned off.

CMOS: The "chip" that stores the parameters that indentify devices connected to the 
motherboard, like the harddrive and the CD Rom drive.  When the PC boots up, it uses these parameters, to "see" all installed peripherals.  These parameters are also used to select the proper device driver to "run" the device.  If the CPU doesn't "see" a device it will not have peripheral control or access to its data.   

RAM: These are random access memory "chips".  All data or programs stored here is zeroed out when the power is shut off.  System and Application programs are read into RAM to be executed by the microprocessor chip.   With modern multitasking PCs, several programs can run at the same time provided enough RAM is available.  Many slow running  and "broken"  PCs may be fixed by simply adding more RAM "sticks".  Many PC users have systems with large harddrives (10gig or more) and mistakenly feel that they have enough storage space for limitless applications, but computer programs run in RAM, not on the hard drive, even though some hardrive space may be used for virtual memory, where less frequently used parts of a currently used program is rapidly read to and from special harddrive space set aside for virtual use. 
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THE BUS:
The bus is the cabling that looks like a 2 inch belt with ridges.  ISA BUS was the standard until EISA made it obsolete.
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THE HARDRIVES:

Cdrive:  Harddrives may be used for the C,D,E, etc. drives.  Some servers may have even more HDs.  The main device for permanent storage of computer programs and data files.  The media are circular metalic disks that have tracks and sectors.  A new drive must be formatted to create writeable partitions.  Windows or some other operating system may be installed into the bootable partition.  Data is stored here in blocks.  Sometimes these blocks are so randomly spaced that space is wasted.  When this occurs the drive must be reorganized by an accessory utility program called the defragmenter.    

Before HDs,  programs and games were read into RAM from floppy drives or tapes, which took lots of time to load and run.  Now application programs that are previously installed onto the harddrive are loaded into RAM memory during the program run.  In some cases large programs with multiple routine or subroutines, use virtual memory as temporary execution residence for their routines that are infrequently accessed.  
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THE HARDRIVE INTERFACES:

First was the old Seagate ST506s HDs which used the now obsolete ST506 interface on the controller board.  Then came the ESDI interface with more curcuits on the drive instead of the controller card.  SCSI HDs made ESDI interface obsolete.  They use IDE/ATA or ATAPI stand alone common interface that can be used for CDROMs. Older drives were "dumb" and required controller commands.  IDEs drives are smart with onboard controllers, but they do  need device drivers and BIOS support.  Even better drives are the EIDE/ATA-2 which first used LBA  which allowed higher drive sizes than 528MB.  Next came the  ATA-3s which features the SMART technology which self-checks the drives for problems.  Ultra-ATA is the latest in 1995-2000.  They claimed a DMA of 33MBs.
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DATA TRANSFER MODES:

Block-mode data transfers which transfers large amount of data (30% more) without the time costing IRQ interupt. 

Drive caching  allows the drives to keep pace with the CPU.  HDs with caching has some RAM memory that used to store predicted data that can be loaded much quicker than directly from the slower HDs disks.  

Bus mastering which used DMA(direct memory access) instead of PIO(programmed I/O) which used much more CPU time.  

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(c)2004 Evans,J., JMLI.T.