| Posted By
Charlemagne
on 2024-02-29
14:38:59
|  The "first" boot of Fridi
Dear Zealous 4 Commodore Plus/4,
I know, I know (and I know) this is not a sensational news in emulation-category (mainly in among better-and-best of emulators), but I was very happy when Fridi made its very first step on this path: booting (, but no more, for now).
To be continued, of course...
Now Fridi knows all legal instructions and video modes. I would like to ask which Plus/4 programs use illegal instruction(s)? Do you know one at least?
Have a good emulation.
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Posted By
Csabo
on 2024-02-29
22:09:40
| Re: The "first" boot of Fridi
First thing I thought of was the old "defenders", e.g. Terra-X and most other older games by TCFS have those. The code uses "illegal opcodes" to obfuscate what's it does. There's probably a lot more examples one could find, e.g. I think using "LAX" (LDA + TAX) is very common in demos, but that should be good enough to test with.
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Posted By
SukkoPera
on 2024-03-01
03:46:52
| Re: The "first" boot of Fridi
I take this is a new emulator you're writing... If that's the case, congratulations, well done! I'm sure it must be a very satisfying moment when things start coming together  .
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Posted By
Charlemagne
on 2024-03-03
16:32:17
| Re: The "first" boot of Fridi
Csabo: Thank you for this information, so LAX is to be implemented.
SukkoPera: WoW, thanx. I am fond of computers and examining how they are working.
Now, you can write simple text and programs in it:
To be continued, of course...
(FunFact: You can write ROM and examine how some routines work: eg. POKEDEC("D008"),255)
Have a good treasure hunting!
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Posted By
Lavina
on 2024-03-03
17:18:32
 | Re: The "first" boot of Fridi
Great job!
Both Promised Land and False Idols use many undocumented opcodes for saving on precious cycles.
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Posted By
Charlemagne
on 2024-03-05
17:40:57
| Re: The "first" boot of Fridi
Lavina: Thank you, but these are only the very first steps, I may be mad before "done" (or the next step)... Well, would you be so kind and list those unofficial instructions you used? They may be in one of your Excel tables...
I sweat blood with interrupt, but this version has got an Easter Egg: SYS 32000
To be continued, of course...
Have a good interruption.
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Posted By
Csabo
on 2024-03-05
18:39:34
| Re: The "first" boot of Fridi
There are some pretty detailed lists of all of the "illegal" opcodes, e.g. this one.
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Posted By
gerliczer
on 2024-03-06
00:05:25
| Re: The "first" boot of Fridi
Or the No More Secrets document over at CSDb. It is actively maintained. Its latest revision was released last Christmas.
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Posted By
Charlemagne
on 2024-03-06
04:31:53
| Re: The "first" boot of Fridi
Csabo & gerliczer: OK... there are some lists such like this, but I don't think that all of them are worth implementing, or do??? So I would like to implement only those are using really.
For example Csabo mentioned LAX above.
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Posted By
Csabo
on 2024-03-06
08:32:55
| Re: The "first" boot of Fridi
Not sure what your ultimate goal is with this, but if you're coding an emulator, you have to implement all of them (with the possible exception of a few, which are unreliable).
If you just want to approach this in a piecemeal fashion, and keep adding new instructions one-by-one, my above mentioned example (Terra-X) is probably a good test case. Get that to run as a first step Looks like it uses LAX, SAX, DCP and the NOP variants.
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Posted By
Charlemagne
on 2024-03-08
15:41:57
| Re: The "first" boot of Fridi
Csabo: Thank you for your reply & help! ...and first of all thanx Plus4World for perfect descriptions (eg. keyboard matrix, for now)
Well, It is very kind of you that you suppose me to capable of reaching unlimited expectations, but nobody can come anywhere near IstvanV & Gaia, and my goals are not that. Who knows me (for example You Csabo) they know that I go my own way and the Charlemagne productions are a little bit different from any other ones. Following "Free your mind"-theory.
Yes I will go forward step-by-step and I want to make both ends meet... So my first step is not going to be that you mentioned (Terra-X), I would be happy that Fridi can execute your sample programs enclosed your Plus4IDE.
But there are a lot of things to do before that... I beg to remark that all of these seem to be more easy that I expected for the first time, because here you "can only write" some instructions and the ROM will make everything else... ...but when I wrote Turbo Vision 4 BASIC, I had to do everything from the first byte to the last one: storing BASIC and Assembly programs and variables in memory, handling stack and loop variables, gosub-return, what's more... the "3-Plus-1" applications, making functions for spreadsheet, storing and managing databases, editing text in word processor by special characters (alignment: center, justify, etc)... drawing shapes on graphics screens (eg. circle, etc) ...uncountable possibility... Happy old days!
And now Fridi has got another Easter Egg: SYS32000 (SPACE Easter Egg):
Have a good keypressing!
(BTW: an example for "a bit difference": you can use F1 to F8 as function keys, not SHIFT+F1...F4)
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