PCI 2.2 interface backward compatible?

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Daemon Poster
Can cards with 64Bit/66Mhz PCI 2.2 interfaces work in standard 32bit/33Mhz PCI slots found on all modern desktop motherboards? Specifically, can this RAID card work in a normal PCI slot?


Fully Optimized
The 32-bit Peripheral Component Interconnect bus or in practice commonoly known as 32-bit PCI bus is a local bus standard is used for attaching peripheral devices to a computer. Devices such as integrated circuits that are fitted onto the motherboard, or expansion cards that fit into slots.

A bus is a subsystem that transfers data or power between computer components inside a computer or between computers. Unlike a point-to-point connection, a bus can logically connect several peripherals over the same set of wires. Each bus defines its set of connectors to physically plug devices, cards or cables together.

The 32-bit PCI bus has replaced the ISA and VESA Local Bus and provides direct access to system memory for connected devices, but uses a bridge to connect to the frontside bus and therefore to the CPU.

32-bit PCI Golfinger Voltage Visual Comparison

The PCI bus originally operated at 33 MHz using a 32-bit-wide path. Revisions to the standard include increasing

32-bit PCI Slot Voltage Visual Comparison

the speed from 33 MHz to 66 MHz and doubling the bit count to 64. Currently, PCI-X provides for 64-bit transfers at a speed of 133 MHz which equates to 1-GBps (gigabyte per second)!

32-bit PCI cards use 47 pins to connect (49 pins for a mastering card, which can control the PCI bus without CPU intervention). The PCI bus is able to work with so few p ins because of hardware multiplexing, which means that the device sends more than one Bus Comparison Chart
Bus Type Bus Width Bus Speed MB/sec
ISA 16 bits 8 MHz 16 MBps
EISA 32 bits 8 MHz 32 MBps
VL-bus 32 bits 25 MHz 100 MBps
VL-bus 32 bits 33 MHz 132 MBps
PCI 32 bits 33 MHz 132 MBps
PCI 64 bits 33 MHz 264 MBps
PCI 64 bits 66 MHz 512 MBps
PCI 64 bits 133 MHz 1 GBps

s ignal over a single pin. Also, PCI supports devices that use either 5 volts or 3.3 volts.

Conventional PCI bus specifications
33.33 MHz clock with synchronous tr ansfers
Peak transfer rate of 133 MB per second for 32-bit bus width (33.33 MHz × 32 bits ÷ 8 bits/byte = 133 MB/s)
32-bit bus width
32-bit address space (4 gigabytes)
32-bit port space (now deprecated)
256-byte configuration space
3.3- or 5-volt signaling
Reflected-wave switching
Conventional PCI variants

PCI 2.2 allows for 66 MHz signalling (requires 3.3 volt signalling) (peak transfer rate of 533 MB/s)
PCI-X changes the protocol slightly and increases the data rate to 133 MHz (peak transfer rate of 1066 MB/s)
PCI-X 2.0 specifies a 266 MHz rate (peak transfer rate of 2133 MB/s) and also 533 MHz rate, expands the configuration space to 4096 bytes, adds a 16-bit bus variant and allows for 1.5 volt signalling
Mini PCI is a new form factor of PCI 2.2 for use mainly inside laptops
Cardbus is a PCMCIA form factor for 32-bit, 33 MHz PCI
Compact PCI, uses Eurocard-sized modules plugged into a PCI backplane.
PC/104-Plus is an industrial bus that utilizes the PCI signal lines with different connectors.
Advanced Telecommunications Computing Architecture (ATCA or AdvancedTCA) is a next-generation bus for the telecommunications industry

So...any PCI device runs on the PCI Northbridge standard. If it's PCI, as is the card you highlighted, then it will run any any PCI slot.
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