COTS PCI104 Board

PCI104 Bus

[ PCI/104 Description ] [ PC/104 Pin-Out ] [ PCI-104 Timing ]
[ PCI-104 Interface ICs ] [ PCI-104 Connectors ]
[ PCI-104 OnLine Standards ] [ PCI-104 Cards ]

PCI-104 Bus Description

COTS PCI104 Board

PCI-104 is the newest variation of the standard. PCI-104 removes the old PC XT / AT bus from the specification leaving only the PCI bus. The PCI bus connector is a 4x30, 2mm stack-through connector. PCI-104 cards may still reside in a stack with either PC/104 cards or PC/104-Plus cards. However when PCI-104 boards are combined in a stack with other type boards they must reside on the top of the stack [because they do not have the XT or AT connectors]. If PC/104-Plus cards are used they must reside underneath the PCI-104 cards. PCI-104 boards may only be stacked 4 cards high. This PCI bus operates at 33MHz, 66MHz PCI operations are not supported.

The elimination of the J1 and J2 connectors allows for additional board space for other components. Component height above and below the board has changed to 0.345" on the component side and 0.190" on the bottom side. PCI-104 boards may operate as 3.3 volt only, 5 volt only or Universal boards. The PCI-104 specification defines the mechanical foot print and card power requirements.
This is a stacked bus with no backplane or interconnecting cable. The cards plug into each other.

The older standard PC/104 bus uses the PC/XT, and PCAT card specification (IEEE P996). PC/104-Plus allows the addition of the PCI bus onto the card. The PC/104-Plus adds another connector to accommodate the PCI signals.

In other words a PC104 card is just like the [old] Personal Computer PC-XT interface card, or PC-AT interface card, and the PC104-Plus board is just like an older mother board with ISA slots and PCI slots. This standard is widely used for embedded computing application even though the PC ISA bus has been obsolete for years now. This PCI bus operates at 33MHz, 66MHz PCI operations are not supported.

The card size for each of the PC/104 standards is shown below.

PC104 Embedded Bus Card dimensions
Card Dimensions / Form Factor

Boards may be stacked 6 high when using the PC-AT [PC/104] bus, but only four of the boards may use the PCI bus.

PCI/104 Express is the newest variant of the PC/104 series of standards.
Similar to the introduction of the PCI/104 interface in many other board formats, PCI/104 now uses the PCI Express [PCIe] electrical interface.

{PCI-104 Bus top}

PCI-104 Bus Pin-Out

PCI-104 Pinouts [signal assignments]
Pin out signal name table for the PCI-104 interface bus.
Note this I/O no longer carries the XT/AT interfaces, and only handles the PCI bus signals.

{PCI-104 Bus Index}

Data Bus Transfer Timing

Only the PCI bus remains in this version of the specification.
The PC/104-Plus [which adds the PCI bus], and PCI-104 timing is derived from the PCI specification.
So all timing and signally is based on the PCI specification.

{PCI-104 Bus top}

PCI-104 Bus Interface IC Vendors

The PCI-104 bus and the PC/104-Plus addition to PC104 use normal CMOS devices for the PCI Bus interface.
Basically the same integrated circuits used with a normal CompactPCI interface.

Integrated Circuit manufacturers by function:
Memory Chip Manufacturers
Processor Manufacturers
Chip Set Manufacturers
Glue Logic Manufacturers

{PCI/104 Bus top}

PCI-104 Online Standards and Specifications

PCI-104 Specification [Version 1.0, 2003]

PC/104 Specifications {VersaLogic Corp.}

PC/104 and PC/104-Plus Specifications {}

PC/104 Spec ver 2.5, PC-104-Plus Ver2.0, PCI-104 V1.0 {PC/104 Consortium}

There are yet two newer and faster PC/104 variations, both using the form factor;
PCI/104 Express [which uses the PCIe specification]
StackableUSB [which uses the USB specification]

{PCI104 Bus Index}

PCI-104 Bus Connector Manufacturers

The PCI side of the card for PC/104-Plus boards or PCI-104 boards use a 4 x 30 (120-pin) 2mm pitch stack-through connectors or non-stack-through connectors.
While the older PC104 bus has .100" spacing, and may be 'stack-through' (pins extend out the other side of the PWB), or 'non-stack-through (normal PWB mounting). The PC/104 8 bit XT card uses a 62 pin connector, and the 16 bit AT version adds another 40 connector.
PC XT/AT connectors are not part of the PCI104 specification.

PCI/104 Connector Vendors;

ept {PC104 Connectors-PC104 Plus Connector Manufacturer}

Teka Interconnection Systems {Solder Flux Bearing Lead Connectors}

Tyco Electronics {PC/104 Connector Manufacturer}

Topic Navigation: Engineering Home > Interface Buses > Backplane Interface Standards > PCI/104 Board Standard.

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Modified 6/13/15
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