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An other RTC
| Description | Download ! | Documentation | Pictures and Schematics | History |
The main problem with the DS12887A is its size : you cannot close your TI with it inside and it's almost impossible to have it and the plus module at the same time, without speaking of the TI89. That's why we decided to interface a new chip : the 72423 (whose manual can be found here) which is a very little thing as you can see below.
Here is a package contaning stuff about
interfacing a 72423 RTC to the TI92 bus.
This isn't too much difficult as you could see.
Files contained in the zip:
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The even smaller thing you can see on the back of the chip is a 74HC02, a gate we use to invert a signal. The program running on the picture below is a TSR; Like this, we can use the calc normally. You'll need to patch the TIOS if you want the RTC running well on a TI92+/89... i.e: In AutoInt1 (For TI89/92+ only) the TIOS write the key code at a debug port: $C00000. Actually, for us, it seems that it is really useless, so why couldn't we use this Chip Select ???
Here is the instruction to patch: move.w (4,a7),(A0) A0 pointing to, guess what, $C00000... and in stack you will find the key code .w long. Simply replace this instruction with two nop;
Replace $30AF 0004 with $4E71 4E71, et voilà !
on ROM 2.03: @ to patch: $4A2A90
on ROM 1.01: @ to patch: $49D2AE
on ROM 1.00: @ to patch: $49CB80
Click on the pictures to enlarge
11/06/2000 -
- Updated the documentation.
06/12/1999 1.0
- First release of the 72423 project.
DBA [] |
