Gestetner A193 Service Manual page 799

Network Interface
One interface slot is provided for installing a network interface card (NIC).
Parallel Interface
The D8905 provides a bi-directional parallel interface (IEEE 1284). To protect
parallel communication from noise, the circuit for control signals (like
STROBE and AUTOFEED) uses Schmidt trigger TTL.
Serial Interface
RS-232C is supported, using the UART provided in the D8905.
IDE Hard Disk Interface
Chip select and address lines from the D8905 are used for providing the
necessary signals to the hard disk. The 16-bit IDE data line is connected to
the D8905 for the byte-to-word packing.
Engine Interface
a second UART unit in the D8905 is used for serial communication with the
machine.
Jumpers (Printer Controller Board)
JP1:
Default is open (factory use only)
JP2, JP3:
Both jumpers (JP2, JP3) must be shorted when the printer controller is
installed without the printer enhancement unit. Both jumpers must be opened
when the printer enhancement unit is installed.
JP4:
Switches between ROM types.
Open: Normal (OTP) ROM
Short: Page Mode (mask) ROM
Note: Normal (OTP) ROM has a label on the top of the chip to
distinguish it from page mode (mask) ROM (which has no label).
(A643) 1-10 SM