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Forums > C64 Coding > Keeping a few bits of information in a hostile environment
2021-04-18 09:24
Krill

Registered: Apr 2002
Posts: 2804
Keeping a few bits of information in a hostile environment

If not reserving space in RAM, where would read-writable data be most likely to survive throughout the run-time of any random demo or game?

$D800-$DC00 is often overwritten entirely, $00/$01 in RAM are too cumbersome to access.

$DD03 (parallel port data direction register) might be good, or maybe the 2x4 CIA TOD registers at $DC08 and $DD08.

Or are they? What else could be usable for that purpose? =)
 
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2021-05-04 13:52
Rastah Bar

Registered: Oct 2012
Posts: 336
Thanks for the explanations!
2021-05-05 03:45
Cruzer

Registered: Dec 2001
Posts: 1048
Had to look up heuristics, and found this very useful definition...

2021-05-05 07:15
map

Registered: Feb 2002
Posts: 27
Quoting Krill
But then i think the simple and safe solution of having the user shuffle over the drive type from installer return values struct to save/code upload parameter struct is acceptable.
Not as elegant, of course. =)


From all mentioned approaches this one sounds the best from my point of view. Leave the responsibility to find a good spot in the memory to the integrator of the Loader. Agreed, that it is less elegant.
Maybe having the Drive code to send some identification would be a good aproach as well as mentioned before but will cost not available resources and creates overhead.
2021-05-06 15:41
Sparta

Registered: Feb 2017
Posts: 35
While waiting for Krill's saver plug-in, try out Sparkle 2's hi-score file saver! :)
2021-05-07 12:32
Zibri
Account closed

Registered: May 2020
Posts: 304
Quoting Cruzer
Had to look up heuristics, and found this very useful definition...


lol for the "useful definition", anyway:

Heuristic comes from ancient greek and it's root is the verb EURISKO which means "to find".
A heuristic algorithm is a non deterministic one, is an algorithm, usually slower but sometimes needed, which employs a search function for a predetermined pattern or behaviour. Our brain for example uses both but mainly the heuristic method.
In short, any heuristic program or line of thought, basically does an "educated guess".
2021-05-07 13:33
Krill

Registered: Apr 2002
Posts: 2804
The better your heuristics, the more (H)EUREKA! moments you'll have.
2021-05-16 18:18
Krill

Registered: Apr 2002
Posts: 2804
Meanwhile, i have actually managed to query drivetype before uploading the appropriate piece of custom code. =)

All without any extra code on 1541 side or in the resident loader portion.

So no hiding nor manual shuffling-around of those two bits required. \=D/
2021-05-16 19:09
JackAsser

Registered: Jun 2002
Posts: 1987
Quote: Meanwhile, i have actually managed to query drivetype before uploading the appropriate piece of custom code. =)

All without any extra code on 1541 side or in the resident loader portion.

So no hiding nor manual shuffling-around of those two bits required. \=D/


Ossom!!
2021-05-17 00:42
Copyfault

Registered: Dec 2001
Posts: 466
Quoting Krill
Meanwhile, i have actually managed to query drivetype before uploading the appropriate piece of custom code. =)

All without any extra code on 1541 side or in the resident loader portion.

So no hiding nor manual shuffling-around of those two bits required. \=D/
This is worth a huge HOORAY!!!

Kudos for getting it done... and thanks for putting effort into it.


Shall I use that "most elegant"-phrase more often ;) ??
2021-05-17 21:35
Zibri
Account closed

Registered: May 2020
Posts: 304
Quote: The better your heuristics, the more (H)EUREKA! moments you'll have.

Precisely.
Eureka comes from the same verb (Eurisko) and it's the first person of the past tense: Literally: "I FOUND [it]" :D
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