| Author | Comment |
marcus777
Probe
Posted: 23 Dec 2008
21:03 GMT
Total Posts: 5 | The TI84+ SE has a 128K RAM chip on-board ... 96K of which cannot be accessed by the user, by default.
What is the trick to allow the processor (Z80 assembly) to access the second set of 64K pages?
Thanks |
BrandonW
Goliath
Posted: 25 Dec 2008
05:03 GMT
Total Posts: 100 | Ports 5, 6, and 7 allow you to swap in an extra RAM page (80h-87h, 81h and 80h being the two main pages).
WikiTI (http://wikiti.denglend.net) has more information.
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turtlbrdr
Marine
Posted: 25 Dec 2008
13:26 GMT
Total Posts: 39 | You can't. The calc uses that area for it's own uses; and while you could possibly store more in the areas set aside for use by asm/apps, it would be to unstable (as these areas are commonly used by asm/app programs.), and they would be unable to be used by basic progs, and by the user themselves without a asm utility to "buffer" the transactions.
---
Head, and only, programmer of StarAeritha Productions |
marcus777
Probe
Posted: 29 Dec 2008
16:48 GMT
Total Posts: 5 | Thanks much BrandonW. Port 6 is what I was looking for; lets me swap in page 0h83 - oh87 from RAM. Bit 7 selects the RAM versus the ROM. This is really exciting... I knew that the ROM pages could be swapped in (its how b_calls work) but it was a great surprise to find out that the rest of that 128k memory space is actually available for use. Yippiiie.
How clever... using a port to select memory address lines...
Thanks again.
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