Pc/104 Bus Expansion - Technologic Systems TS-5700 User Manual

TS-5700 User's Manual

15 PC/104 Bus Expansion

The PC/104 is a compact implementation of the PC/AT ISA bus ideal for embedded applications. Designers
benefit from using an already-developed standard, rather than creating their own. Further, the presence of a
compact form-factor PC compatible standard has encouraged the development of a broad array of off-the-shelf
products, allowing a very quick time to market for new products.
The electrical specification for the PC/104 expansion bus is identical to the PC ISA bus. The mechanical
specification allows for the very compact implementation of the ISA bus tailor made for embedded systems. The
full PC/104 specification is available from the IEEE Standards Office under # IEEE P996.1. Basically, this bus
allows multiple peripheral boards in a 3.6 inch by 3.8 inch form factor to be added in a self-stacking bus. Since
the electrical specs are identical (except for drive levels) to a standard PC ISA bus, standard peripherals such
as COM ports, Ethernet, video, LCD drivers, and Flash drives may be easily added using standard drivers
The TS-5700 implements a sub-set of the 8-bit or optionally the 16-bit version of the PC/104 bus. We have
found this allows the support of the vast majority of PC/104 boards including all of the above mentioned
examples.
IRQ3 and IRQ4 are typically used by COM2 and COM1 and are not available on the PC/104 bus. If a peripheral
board must use either IRQ3 or IRQ4, it is possible to reconfigure the Elan520 registers and reassign IRQ lines.
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Pin B19 (normally not used) has been reassigned to be a User Chip Select. This active low signal decodes the I/
O address range 140h through 15Fh, to allow for simple low-cost peripheral board designs.
All Technologic Systems 3000 and 5000 series products will support the User Chip Select feature.
Memory range C8000-CFFFF is available for custom peripheral boards to map into the memory space on the
PC/104 bus. See section 19.4
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for details.
on configuring the Custom CMOS settings.
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