info about buses (ISA, EISA, MCA, PCI, VESA, etc...)

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danielshoes

Senior member
Dec 12, 2000
293
0
0
Hi folks!
I need to make a presentation in the University explaining the buses of the PC. I was wondering if someone in forums knows good sources telling about buses. I do not want to build up a "PC buses manual", nor present something too simple, that any newbie knows. Something in the middle, talking a little bit about the oldies (I am pretty sure I will find buddies who know what a MCA bus is and even had a VESA Local bus video card) and some technical material, overviewing the technologies.

FAQs helped me to find some very good stuff about AGP. Tkx to Andy Hui and BenSkywalker. Good job with those FAQs!

Cool links, docs, etc... feel free to post or e-mail me.
Thanks and regards.
 
J

jhu

Lifer
Oct 10, 1999
11,918
9
81
do you only want info on the more common buses? or do you also want info on buses on other architectures (sun sbus, apple nubus, etc.)?
 
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HappyPuppy

Lifer
Apr 5, 2001
16,997
2
71
Go to the library, or Barnes and Noble etc. and thumb through an A+ certification book. They usually explain all the current and legacy buses.
 
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danielshoes

Senior member
Dec 12, 2000
293
0
0
jhu, just these common buses from PC. To be more exact, I am focusing the expansion buses, like PCI 32/64, ISA 8/16, VESA, AGP 1-8X, MCA, CNR, AMR, ACR, etc...

The part regarding AMR, ACR and CNR is ready (I am walking backward :) ). The hardest stuff to find is good info about the early times, like ISA 8/16 bits and MCA.

HappyPuppy, thanks for the tip, but from Brazil it will certainly hard to do... :)

I appreciate good links (or even a ready doc, if someone have it).

 
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RanDum72

Diamond Member
Feb 11, 2001
4,330
0
76
ISA is the oldest bus. MCA is IBM's attempt to corner the bus market and get fees for licensing it. The reaction to it is EISA which is 32bit and backwards compatible with both 8-bit and 16-bit ISA. You can also say that EISA and MCA are the first true plug-and-play buses. They require no jumper settings. EISA has its configuration handled by software (usually loaded up by a floppy) and shares IRQ's. I remember my first SCSI setup, with an Adaptec 2742T EISA SCSI adapter (ithas TWO SCSI buses in one card) with an extremely loud and hot DEC 1.3gig 5400rpm drive and MAxtor 540mb. The good old days....sigh...
But both MCA and EISA are limited because although they are 32 bit they run at a rather slow clock speed. EISA was 8mhz ( to retain compatibility with ISA) while MCA can run at 16mhz. Thus, the Vesa Local Bus (VLB) bus was born. Its basically an extension to the ISA slot and its original purpose is similar to today's AGP, which is basicallyto speed up graphics by having a more direct access to the CPU and memory. However VLB was also utilized for IDE controllers( this is where Promise got a name for themselves). The max. clock speed for VLB was 66mhz, but it was more commonly used at 33mhz. At this speed, you can use up to three VLB slots. Later on, the 486DX 40 with a FSB of 40mhz was made and the VLB bus was bumped to 40mhz also. At this speed, only two VLB slots can be used. Later on, a 486 DX50 was made (at 50mhz FSB). Only one VLB slot can be used at tis speed and its usually flakey (40mhz was pretty stable but considering that during those days Win 3.1 was used, stability was measured in hrs:))
VLB was also a PITA because it was extremelyhard to attach VLB cards to the slots. Shorty after VLB, Intel came out with PCI and the rest is history.

I still have the book "hardware bible" printed back in 1994 and it comes in handy for reminiscing old hardware...
 
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