The ISA architecture bus has long been a popular choice for embedded applications. With the publication of the PC/104 standard in 1992, this bus architecture was available on a small, rugged form factor which has since become an industry standard. As technological requirements advanced, a need began to arise for a higher performance bus throughput. This is especially true when it comes to graphics devices as well as other high-speed I/O devices such as networks. The PC/104 Consortium met this challenge by incorporating a PCI bus on the PC/104 form factor, which became to be known as PC/104-Plus. This architecture provides a link to versatile legacy hardware while meeting the high-speed requirements for present and future hardware.

To accommodate the gradual replacement of ISA bus devices with PCI devices, the PCI-104 was approved by the PC/104 Consortium. PCI-104 is a PCI-only architecture that accommodates the advances of PCI devices in a small rugged form factor.

This document supplies the mechanical and electrical specifications for the “PCI-104” which has the advantage of the high-speed PCI bus.

Summary of Key Differences From PC/104 Specification:

1. The AT and XT connectors for the ISA bus have been removed.
2. The component height on the topside has been reduced from 0.435″ to 0.345″ and the bottom has been increased from 0.100″ to 0.190″ to increase the flexibility of the module.
3. Control logic added to handle the requirements for the high-speed bus.

Summary of Key Differences From PC/104-Plus Specification:

1. The AT and XT connectors for the ISA bus have been removed.

Summary of Key Differences (120-pin PCI and PCI Local Bus Specification)

1. The PCI bus connector is a 4×30 (120-pin) 2mm pitch stack-through connector as opposed to the 124-pin edge connector on standard 32-bit PCI Local Bus.
2. The 120-pin PCI does not support 64-bit Extensions, JTAG, PRSNT, or CLKRUN signals.