41CL: Second set of Main RAM
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04-26-2014, 02:37 PM
(This post was last modified: 04-28-2014 06:42 AM by Ángel Martin.)
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41CL: Second set of Main RAM
Quick on the heels of the previous topic ( 41CL: Second Set of Extended memory ) - here comes the follow-up dealing with MAIN memory, i.e. Data registers and Programs.
The method is exactly the same, but one must be careful not to swap the RAM with an invalid copy in the higher page: the status register c in particular is very sensitive to this experiments and balks at improper values! Therefore it's important to "prime the pump" before executing MMSWAP for the first time - and that's the mission of MMCOPY: use it to copy the current contents of the main RAM to the upper page. MMSWAP includes status registers c,d, and e - but none of the others. This scheme provides compatible key assignments but leaves alone the program pointer. Stating the obvious, make sure MMSWAP runs from ROM (HEPAX, or otherwise) - or else you'll get nice pyrotechnics and a likely MEMORY LOST event. Below the program listings for MMCOPY: Code:
and here's the combined MMSWAP and XMSWAP together (lots of shared code): Code:
Cheers, 'AM PS. The attached pdf contains both programs in a nicer format - does anybody know how to get the code properly formatted in the post window??? "To live or die by your own sword one must first learn to wield it aptly." |
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41CL: Second set of Main RAM - Ángel Martin - 04-26-2014 02:37 PM
RE: 41CL: Second set of Main RAM - Ángel Martin - 04-27-2014, 06:40 AM
RE: 41CL: Second set of Main RAM - Ángel Martin - 04-28-2014, 06:43 AM
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