The Bush Set Top Box Hardware - North West
The left hand side of this area is concerned with the analog side
of the integral modem. The components starting with the small
isolating transformer and going up to the phone socket at the top of
the picture comprise this section.
The right hand side of the image shows the SMsC FDC37C669 SuperIO Chip.
- This component provides
- The parallel port which can be seen directly above the device in the picture.
- The serial interface for the infra red keyboard, which is
connected the second serial port - note this does not use the
IR capabilities of the controller, which is just used as a 9600baud
serial port.
- The IDE, primary serial port, floppy disc and IR functionality of
this part are not ordinarily used. However on my board a
modification has been made so I can gain access to the primary serial
port. Two small white wires have been attached to the
unbufferd TTL level recive and transmit lines on the
FDC37C669. These lines have been taken to a header which can be seen
elsewhere on the board.
- The SMsC FDC37C669 is
clocked at 24Mhz which is derived from the CPU clock. It is possible
to do this because the FDC37C669 has a control register which allows a
scaling to be used removing the need for an additional 14.318Mhz
reference clock.
Note the odd resistor on the right of the picture, this seems to
have been a late modification and is present on all boards I have
seen. Needs more investigation!
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