the problem mentioned previously, the following is a list of other difficulties
met along the way and some of the solutions.
The Real Time Clock DS1287 had been used for ITDL, but I found that programming
it and interfacing it to the system was a troublesome process. For this, Dallas
Semiconductors suggested changing DS 1287 to their latest Real Time Clock (RTC)
series and I chose DS 1742 which is easily configurable and equivalent to the
operation of RAM.
Synchronization problem due to two crystals operating at two frequencies for MT
8870 and Z80. Employing one crystal for the both with necessary buffering has
ITDL should be tested for considerable amount of time period before its
The condition 2. of main program, Do while true has been omitted to prevent RAM
get overloaded and replaced with Do Until N=16371 (3FF3h).
The length defined for Call duration (i.e. 1 Byte) in 5.
Information Storage has restricted the maximum call duration. Therefore,
maximum call duration storable is 255 minutes and 59 seconds.
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