Day Eight

Daniel Berry

(Page 72, Supporting Microcomputers)

Bus Systems

The bus system is a network of very small pathways, which are embedded within the motherboard. There main purpose is to transfer data from the CPU to the devices, which are in the expansion slots of the motherboard. These devices include, but are not excluded to: internal modems, video cards, multimedia cards, sound cards, and SCSI cards.

PC BUS ARCHITECTURE

Industry Standard Architecture

ISA

Introduced by:	Year	Bit size	MHz speed
IBM	1984	8 bit, 16 bit	8 MHz

Allowed bus mastering, which is the ability for devices to transfer data to each other without intervention from the CPU or RAM.

Micro Channel Architecture

MCA

Introduced by:	Year	Bit size	MHz speed
IBM	1987	16 bit, 32 bit	10 MHz

Allowed bus mastering, which is the ability for devices to transfer data to each other without intervention from the CPU or RAM.

Discontinued

Extended Industry Standard Architecture

EISA

Introduced by:	Year	Bit size	MHz speed
Various PC manufactures	1987	16 bit, 32 bit	8 MHz

Could support ISA cards as well as EISA cards

Allowed bus mastering, which is the ability for devices to transfer data to each other without intervention from the CPU or RAM.

Discontinued

Vendors Electronics Standards Association

VESA (VL Bus)

Introduced by:	Year	Bit size	MHz speed
Vendors Electronics Standards Association	1992	32 bit	Same as CPU

Could support high-speed video cards.

Discontinued because there was no standard adapted for this slot and compatibility problems were constant.

Peripheral Component Interconnect

PCI

Introduced by:	Year	Bit size	MHz speed
Intel	1992	32 bit and 64 bit	133 MHz

Could support as many as 10 PCI devices in a single PC.

Allowed multiple bus mastering, which is the ability for devices to transfer data to each other without intervention from the CPU or RAM.

Replaced the VESA bus.

Allowed transfers of 132 Megs per second.

Personal Computer Memory Cards Industry Association

PCMCIA

(PC Card)

Introduced by:	Year	Bit size	MHz speed
Nippon Manufactures	1990 and 1995	32 bit	33 MHz

Could support hot swap ability.

Allowed bus mastering, which is the ability for devices to transfer data to each other without intervention from the CPU or RAM.

Accelerated Graphics Port

AGP

Introduced by:	Year	Bit size	MHz speed
Intel	1998	64 bit	66 and 133 MHz

Dedicated to high speed video cards

Allowed the Video card to have a special pathway or bus so that other devices would not hinder transfer of data of the video card.

Allows for transfers of more than One Gig per second.

Communication Network Riser

CNR

Introduced by:	Year	Bit size	MHz speed
Intel	1998

Special bus devoted to modems and audio cards, which supports Intel’s CNR (Communication Network Riser) specification. May appear on motherboard specs as Audio Modem Riser or AMR. These devices lower cost dramatically.

Group Activity

BUS ARCHITECTURE

A+ Questions

What bus architecture is the fastest?

a) MCA

b) ISA

c) VESA Local Bus

d) PCI

Which is both a 16 and 32 bit bus?

a) ISA

b) EISA

c) PCI

d) PowerPC

IBM's Micro Channel Architecture (MCA) specifies which type of the following bit access widths?

a) 8 bit & 16 bit

b) 16 bit & 24 bit

c) 16 bit & 32 bit

d) 32 bit & 64 bit

Which type of system board is the MOST likely candidate for processor upgrading if you want maximum performance and future compatibility?

a) ML

b) PCI

c) ISA

d) EISA

Which modern bus would have a video adapter installed on it?

a) ISA

b) EISA

c) PCI

d) AGP