Meinberg DCF77 PC32, Operating Instructions Manual

Page: 7 / 22

7
Overview
Several product lines of radio remote clocks for IBM compatible computers are
available from Meinberg. While all of them are using a common software interface,
different computer architectures require different board layouts. So the board called
PC32 can be installed in every standard PC with ISA or EISA bus. PC32E is the name
of the corresponding eurocard size board for 19" modular computers with AT96 or
ISA96 bus. Microchannel architectures (e. g. IBM PS/2 Model 50 and above) are
supported by our microchannel adapter PS31.
An external ferrit antenna makes the signal from DCF77 available to the on-board
long wave receiver. The demodulated time marks are decoded by the clock´s micro-
processor. If no errors are detected in the current time message an additional plausibi-
lity check against the previous time message is performed. If that plausibility check
passes, too, the battery buffered real time clock on the board is synchronized corre-
sponding to the decoded time and date.
Software running on the computer can read out the date/time/status and some more
information. Access to the board is made via writing to/reading from two I/O ports.
The simple software protocol to be used is described below. Starting with EPROM
version 3.0, the on-board clock can be set via the PC interface. It is possible but not
necessary to let the board generate periodic hardware interrupts on the computer bus.
Utility programs supplied with the boards include PCPSDRV.COM, a resident
driver (TSR) for DOS/Windows that keeps the computer´s system time synchronous
to the board time and PCPSINFO.EXE, a status display which simplifies installation.
Drivers for OS/2, Windows NT, or NetWare can be ordered separately. Sample C,
pascal, and assembler programs including source show how the board can directly be
accessed from user-written applications.