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4.2.5 PCI Expansion Slots
Four dedicated PCI expansion slots are provided on the AlphaPC 164LX. This
allows the system user to add additional 32-bit or 64-bit PCI options. While both the
32-bit and the 64-bit slots use the standard 5-V PCI connector and pinout, +3.3 V is
supplied for those boards that require it. The SIO chip provides the interface to the
ISA expansion I/O bus.
4.3 ISA Bus Devices
Figure 4–4 shows the AlphaPC 164LX ISA bus implementation with peripheral
devices and connectors. Two dedicated ISA expansion slots are provided. System
support features such as serial lines, parallel port, diskette controller, keyboard/
mouse control, and time-of-year clock are embedded on the module by means of an
FDC37C935 combination controller chip. Also shown is the utility bus (Ubus) with
its system support devices.
4.3.1 Combination Controller
The AlphaPC 164LX uses the Standard Microsystems Corporation FDC37C935
Ultra I/O combination controller chip (see Figure 4–4). It is packaged in a 160-pin
PQFP configuration. The chip provides the following ISA peripheral functions:
•
Diskette controller–Software compatible to the Intel N82077 FDC. Integrates
the functions of the formatter/controller, digital data separator, write precom-
pensation, and data-rate selection logic requiring no external filter compo-
nents. Supports the 2.88MB drive format and other standard diskette drives
used with 5.25-inch and 3.5-inch media. FDC data and control lines are
brought out to a standard 34-pin connector (J15). A ribbon cable interfaces the
connector to one or two diskette drives.
•
Serial ports–Two UARTs with full modem control, compatible with NS16450
or PC16550 devices, are brought out to two separate onboard, 9-pin
D-subminiature connectors (J4).
•
Parallel port–The bidirectional parallel port is brought out to an onboard 25-pin
connector (J13). It can be brought out through a 25-pin female D-subminiature
connector on the bulkhead of a standard PC enclosure.
22 January 1998 – Subject To Change
ISA Bus Devices
Functional Description
4–7
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