Atari ST Frontier FMC II Clock
Modification - September 18th 2006 -
v1.03.
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1.
Introduction.
2. Important hex file locations.
3. Attempting to modify
software to run from 0 thru 99.
4. Final solution with years of upto
2059.
5. Conclusion.
1.
Introduction.
================
The Frontier FMCII clock software will not
allow years to be set of 2000 and beyond. Is it possible to correct
this?
2. Important hex file
locations.
================================
Using a hex file editor the
following locations have been determined as being important in changing how the
vanilla manufacturer's software behaves.
Location: 000D87
Original
Value : 63h
Effect: When clicking DOWN, this is the upper year value that we
roll around to. If the year is 80, and we click down, it rolls round to 99. This
is that '99 number.
Location: 000D7D
Original
Value : 50h
Effect: When clicking DOWN, this is the lowest value we can go
before it rolls over. This is the minimum year. This is that '80 value. When we
hit this number, it rolls around to the number above at location 000D87.
Location: 000EF2
Original
Value : 50h
Effect: When clicking UP, this is the value we roll around to.
Clicking on '99 will rollover to this number. The default of 50h (80D)
causes the number to change to this.
Location: 000EE7
Original
Value : 63h
Effect: This is the maximum year we can go to, when clicking
UP.
3. Attempting to modify software
to run from 0 thru
99.
=======================================================
During testing
prior to this write-up it was proposed that the software be allow to run from 0
thru 99, as opposed to it's original 80 thru 99. The following values were
modified;
Location: 000D7D
Original
Value : 50h
New Value: 00h
Location: 000EF2
Original
Value : 50h
New Value: 00h
This caused the error of "Out of
Data Range," when attempting to set the hardware cartridge. Therefore this
approach was unsuccessful.
4. Final solution with years of upto
2059.
==========================================
It was determined through
experimentation that we could only go up. And it was further determined
that we could only go as far as 2059 being controlled by the following
values;
Location: 000D87
Original Value : 63h
New Value: 9Fh
Location: 000EE7
Original Value : 63h
New Value: 9Fh
The value of 9Fh which is 159 decimal is the highest that the hardware
clock will go. When the clock is set to 2006 for example, the value 106 is
selected. The Atari ST nor the hardware clock appear to complain at
this. Since the ST only works with the final two year digits, this poses
no issues. It should be noted that what little Atari ST which exists to be
function beyond 2000, does indeed report the correct year, ie. 2006. Or in
the maximum case, 2059.
5. Conclusion.
==============
This method has been tested ad-hoc
on a number of systems and reliably produces the desired result. It is
deemed as working.