User`s guide

The 8242 is an Intel UPI-42AH universal peripheral interface. It is an 8-bit
slave microcontroller with 2KB of ROM and 256 bytes of RAM that has been
preprogrammed with a keyboard BIOS for standard scan codes.
Refer to either of the following Intel documents for additional information:
• UPI™-41AH/42AH Universal Peripheral Interface 8-Bit Slave
Microcontroller
• Peripheral Components
3.9.2 Combination Controller
The AlphaPC64 uses the National PC87312 as the combination controller chip
(see Figure 3–13). It is packaged in a 100-pin PQFP configuration. The chip
provides the following ISA peripheral functions:
• Diskette controller—Software compatible to the Intel PC8477 (contains a
superset of the Intel DP8473 and NEC uPD765) and the Intel N82077 FDC
functions. The onchip analog data separator requires no external filter
components and supports the 4MB drive format and 5.25-inch and 3.5-inch
diskette drives. FDC data and control lines are brought out to a standard
34-pin connector. A ribbon cable interfaces the connector to one or two
diskette drives.
• Serial ports—Two UARTs with modem control, compatible with NS16450
or PC16550, are brought out to separate onboard, 10-pin connectors. The
lines can be brought out through 9-pin female D-sub connectors on the
bulkhead of a standard PC enclosure.
• Parallel port—The bidirectional (jumper-controlled) parallel port is brought
out to an onboard 26-pin connector. It can be brought out through a 25-pin
female D-sub connector on the bulkhead of a standard PC enclosure.
• IDE interface control—The IDE control logic provides a complete IDE
interface, including external signal buffers.
An onboard 24-MHz oscillator supplies a reference clock for the diskette data
separator and serial ports.
Refer to National document PC87311/PC87312 (Super I/O™ II/III) Floppy
Disk Controller with Dual UARTs, Parallel Port, and IDE Interface for
additional information.
3–36 Functional Description