at7601fg AME, Inc., at7601fg Datasheet - Page 23

• Manufacturer Part Number: at7601fg
• Description: Printer Port Controller
• Manufacturer: AME, Inc.

Rev. B.02
AT7601F
5-3-2-12 Programmed I/O - Transfer from the FIFO to Host
5-3-2-13 Programmed I/O -- Transfer from the Host to FIFO
In the reverse direction an interrupt occurs when Servicelntr is 0 and ReadlntrThreshold bytes are
available in the FIFO. If at this time the FIFO is full it can be emptied completely in a single burst,
otherwise ReadlntrThreshold bytes may be read from the FIFO in a single burst. ReadlntrThreshold=16-
<threshold>) data bytes in FIFO
An interrupt is generated when Servicelntr is 0 and the number of bytes in the FIFO is greater than or
equal to (16-<threshold>). (If the threshold=12, then the interrupt is set whenever there are 4-16 bytes
in the FIFO.) The PINT pin can be used for interrupt-driven systems. The host must respond to the
request by reading data from the FIFO. This process is repeated until the last byte is transferred out of
the FIFO. If at this time the FIFO is full, it can be completely emptied in a single burst, otherwise a
minimum of (16-<threshold>) bytes may be read from the FIFO in a single burst.
In the forward direction an interrupt occurs when Servicelntr is 0 and there are WriteIntrThreshold or
more bytes free in the FIFO. At this time if the FIFO is empty it can be filled with a single burst before
the empty bit needs to be re-read. Otherwise it may be filled with WriteIntrThreshold bytes.
WriteIntrThreshold=(16-<threshold>) free bytes in FIFO.
An interrupt is generated when Servicelntr is 0 and the number of bytes in the FIFO is less than or equal
to <threshold>. (If the threshold=12. then the interrupt is set whenever there are 12 or less bytes of
data in the FIFO.) The PINT pin can be used for interrupt-driven systems. The host must respond to the
request by writing data to the FIFO. If at this time the FIFO is empty. It can be completely filled in a
single burst, otherwise a minimum of (16-<threshold>) bytes may be written to the FIFO in a single
burst. This process is repeated until the last byte is transferred into the FIFO.
Power management capabilities are provided for the following logical devices: floppy disk, UART 1,
UART2 and the parallel port. For each logical device, two types of power management are
provided; direct powerdown and auto powerdown.
AME, Inc.
Printer Port Controller
23