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Legacy -
ISA bus architecture (16 Bit AT Class)
The ISA - legacy PC/AT-bus is a 16-bit (or x86-)
version of the
PC/XT bus introduced with the Original IBM PC and later with the IBM/AT
PC, it
was officially termed the "I/O Channel" by IBM.
It extends the
original IBM XT-bus by adding a second shorter edge connector in-line
with the eight-bit PC XT- bus connector, allowing retention of
compatibility with most older 8-bit cards. The second inline connector
adds four additional address lines for a total of 24, and eight
additional data lines for a total of 16. It also adds new interrupt
lines connected to a second 8259 PIC (connected to one of the lines of
the first) and four 16-bit DMA channels, as well as control lines to
select 8 or 16 bit transfers. This bus was oringinally comprised of two
discrete "in line" connectors however over time a consolodated single
connector was introduced.
Arbor's ISA form factor SBCs provide full
legacy support for the 16 bit PC-AT bus structure. Arbor's ISA
Bus SBC products strive to maintain compatibilty with legacy hardware
and software needs while at the same time endeavoring to utilize
readily available chipsets from well known suppliers like Intel, STPC,
VIA, DM&P and others.
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