HDD Controllers and Ext Data Bus With RAM?

[Beno]

Hi Every1,

I have just started to study for the A+ exam with the Mike Myers text book.
I highly recommend it but there are just a few questions that I am a little confused over.

Mike said that the Pentium and Pentium Pro Ext Data Buses are 64 bits wide which enables dual processing but quad processing in the Pentium Pro model.
How does Quad processing occur when we have split the 64 bit data bus into 2 pathways. I can understand it for the dual processing but not for the quad processing??

He also said referring to RAM that all commands given to processors from the RAM are given in 8 bit chunks to allow for backward compatability with the 8088 chip, but what is all the talk about 32 bit data buses. If commands are given to the CPU in 8 bit chunks from the RAM then shouldn't we talk about a 8 bit ext data bus?? why 32 bit databus??


ONE MORE!!

Also he said that the earliest hard drives had a special card for the hardrive controller but now they don't because motherboard makers build the controllers directly into the motherboard. These controllers he says truley act only as connectors. So whats controlling the disk accesses to the hard disk then??? Is it the driver software or is there special circuitry underneath where the HDD connects to????

Thanks everyone that could help me

Cheers

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Have a nice day

[geebee76]

Hi Beno, Sorry I can't help with the BUS questions. Too technical for me but someone will be along shortly to help you with this.

In the meantime check out HD section of this site. It will answer all the questions you could possibly ask about HD's.

My understanding is that the early HD's using the ST 412/506 Interface had all the controls on the MB. The introduction of the Enhanced Small Device Interface moved some of the controls from the MB to the HD unit. When the ATA/IDE HD was intoduced all the smarts where moved from the MB to the HD unit.

Hope this helps http://www.PCGuide.com/ubb/smile.gif

[Ghost_Hacker]

He also said referring to RAM that all commands given to processors from the RAM are given in 8 bit chunks to allow for backward compatability with the 8088 chip, but what is all the talk about 32 bit data buses. If commands are given to the CPU in 8 bit chunks from the RAM then shouldn't we talk about a 8 bit ext data bus?? why 32 bit databus??


In really, really simply terms. A x86 CPU "instruction" can be between 1 byte and 3 bytes long.( with todays processor extensions the upper limit may be more) A 32 bit data bus allows more data to be accessed per memory operation . So if the data bus was 8 bits long it would take 3 memory operations to read a 3 byte instruction. With a 32 bit data bus it only takes 1 memory operation. Speed is the name of the game here.

To learn more you should read "The Art of Assembly Language" ( it a free pdf book that any search engine can point you to) the first 3 or 4 chapters deal with how a x86 processor works.


Mike said that the Pentium and Pentium Pro Ext Data Buses are 64 bits wide which enables dual processing but quad processing in the Pentium Pro model.
How does Quad processing occur when we have split the 64 bit data bus into 2 pathways. I can understand it for the dual processing but not for the quad processing??


This really has more to do with the built in L-2 cache of the Pentium Pro when compared to the L-2 cache of the orginal Pentium. Because of improvements to the Pentuim Pro's cache it can support MP systems running 4 Pentuim Pro processors.


Hope this helps http://www.PCGuide.com/ubb/smile.gif




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