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What kind of a buss is a Local Buss?

By harvardd ·
What is a LOCAL BUSS? How does a Local Buss differ from the rest of the busses on a system board?


Is it true that a local buss runs at the same clock speed as the CPU?

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What kind of a buss is a Local Buss?

by danpiers In reply to What kind of a buss is a ...

Local Bus is one of the several standards in motherboard architecture. The original IBM (and IBM-style) motherboards allowed expansion cards to be connected through Industry Standard Architecture (ISA) slots. The first of these were only capableofhandling 8 data bits because the original processor (Intel's 808 used an 8-bit bus and was termed an 8-bit processor. The 80286 processor was a 16-bit model. The ISA slots had a section added to become 16-bit slots. These slots were connected to the system through a bus controller and operated at approximately 8MHz data rate. As processors became faster, the ISA slots still ran at the same old speed. This allowed older expansion cards to be used with the newer, faster processors. With the need for faster expansion cards to perform (primarily) video functions, a faster bus was needed. The first high-speed bus was called the VESA Local Bus (VLB). VESA (Video Electronics Standards Association) was the organization that came up with the new local bus.
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What kind of a buss is a Local Buss?

by danpiers In reply to What kind of a buss is a ...

Instead of going through the slow-speed bus controller, the VLB connected directly to the processor bus. The processor bus ran at 32MHz and was 32-bits wide. It was 4 times faster and pushed twice as much data through with every cycle. This made it almost 8 times as powerful as a standatd 16-bit ISA slot. It was called "local" because it was much closer to the processor than the older ISA bus. The implementation was as an extension to a standard 16-bit ISA slot. Typically, the VLB is a brown-colored connector with finer contacts than the ISA standard. Cards that connect to the VLB extension also connect to the ISA slot it is associated with. The cards have a history of being difficult to install. The front half installs with less force than the back half. Problems with poorly seated cards were common. Another common problem with the VLB extension is in the way it was connected to the processor bus. Since there was little "buffering," too many VLB cards could actually bringa system to a standstill. Eventually, the VLB bus was replaced by the PCI bus, that was properly buffered and used more intelligent Plug 'n Play operations. Hope this helped.

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What kind of a buss is a Local Buss?

by harvardd In reply to What kind of a buss is a ...

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What kind of a buss is a Local Buss?

by harvardd In reply to What kind of a buss is a ...

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