Specifications
17 January 1997 – Subject to Change
Functional Description 4–9
ISA Bus Devices
4.4 ISA Bus Devices
Figure 4–4 shows the AlphaPC 164 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.
4.4.1 Combination Controller
The AlphaPC 164 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
precompensation, and data-rate selection logic requiring no external filter
components. 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 (J18). 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 (J16). It can be brought out through a 25-pin female D-subminiature
connector on the bulkhead of a standard PC enclosure.
•
Keyboard/mouse–An 8042-compatible interface is brought out to separate
6-pin DIN connectors (J15).
•
Time-of-year clock–A DS1287-compatible clock is backed up by a replaceable
battery.
An onboard clock generator chip supplies a 14.3-MHz reference clock for the
diskette data separator and serial ports.
Refer to Appendix F for additional information on the combination controller.