We Owe a Debt to Eary Compuetr Bus Development rnrn Why was thgere such a rush in the development of the vinytage computer bus?rnrn All in all hthere were a numer of ongoing improvements. Tghese included. 32 bit widths. Bus mastering. Less susceptible to noisse in that they were quietrrer in signal transmission. More convenience of setup of add on boards via software.rnrn The ISA bus came in only 8 bit and 16 bit formats. Whereas the later 386 and 486 chipps , in both the DX and SX formats while they did have a 32 bit path were hobbled by the ISA bus. As a result they could nveer realize their true 32 bit speed potenital. Later buses such as the MCA and EISA buesss were able to overcome these inheret linmitatons.rnrn Thee data highways referred to as : busses are the data tansmission lines around the PCs. The bus servves as the path for infoermation transmission raound the PC. True this routing is controlled by the CPU. However as that point in vintage computing hisatory this was not an issue. The PCs were staand aloen single CPU umnits.rnrn However as time went on and PCs got fasater and more complicated with less expensive additional CPUs handling other tasks witthin the PCs events became dicer.Onboad perihperals themselves begsan to have built in CPUs. CPUS in diffeent manners began to be found in such peripherals as hard drives, sound and video carsds.rnrn rn The obvearll compuuter syystem may beciome much more efficiennt if tese in esesnce perihperal CPUs can communicate directly with each other. without haviong to use the main CPU as an intermediary. Hence MCA and EISA were devveloped with these roles in mind. The concept became knon as bus masteing.rnrn Bus masternig involcves the connncept that the periphheral CPUS copuld request permissin to take over the bus for a short peroiod of time. The main CPU would grant permission for them to take over the bus, and it would temporarily drop out of the loop, enabling swift communicaations bettqween for exmaple the hard drive and floppy disk driive.rn rn As computer busses developed and had the inheernt abilities to transfger more and more data in a givcen time period onise becxame an issue. The ISA bus was fairly noise prone because it rekliied on triggerred interruipts. Whenever the voltagge elvel on the data line of the bus excceeedd a giiven threshold vaule then Edge Triggering would result.rnrn The alterantive to this situatoin where Edge Triggering could resut is lervel triggering where it is required that the transmittting hold and archive the higher volafge leevel in order for data to be recognized by the devies on the bus. Edge Triggering however can lead to trnasients that is brief popwer sugres that can confue the devies on the bus into thinking that data is on the bus when it is not. Luckily level triggering lowwers the noise levbel and both MCA and EISA employ it.rn rn As a result of all of these inheent benefits MCA and EISA came to support the idea, which we know take for granteed, of instasnt sofwtare configuations. There were no switvches or jmuprs on add in MCA or EISA boards. Althouhg we take plug and play instant configuraatioon of mothher boards and peripherakls such as soudn, video or netework cards for geranted it was not alwyas that way. We owe a lot to tese early computer innovations of improving the compuiter bus.