There are routines in ROM that move the contents of memory up, or down in the address space. They are used when you add a BASIC line in the middle of a program so that each subsequent line is moved to a higher address, and then everything is re-linked. Can you make a video showing how to use the ROM routines to move data around to any destination you want? Some programs I've seen move screen memory 40 bytes up, so that the text on the screen scrolls downward on the CRT instead of upward. God bless, and have a fun time with the computer!
Hi, nice job explaining and implementing mandelbrot set in our beloved C64. I have couple of ideas maybe you can try yourself. 1, you could reorder collors to get some nice gradients, I chose 8 colors and changed iteration to 8, but it could be easily changed even to all 16 colors, but for small iteration count it is not necessary. important are to get smooth color transition ---------- 2 dim a(7): for i = 0 to 7;read a(i):next 3 data 0,9,8,10,7,3,14,6 ... 160 for i=7 to 0 step -1 .... 230 poke 55296,a(i) --------- idea is from wikipedia where its used just 16 colors in 2 gradients 2. I saw your other video about 10 print chr 223 and chr 233, and it gave me idea to try that here with mandelbrot and i was very happy with result. I used for left upper and lower right part of screen chr(233) and chr(223) for other two quadrants. Then I combined that with black background (bouth 53280.0 and 53281,0) and chose border at midle of mandelbrot set at x=28 (not 20 :-)), somethin like this: --------- 220 if (py<13 and px<28) or (py>=13 and px>=28) then poke 1024+p, 233 220 if (py>=13 and px<28) or (py<13 and px>=28) then poke 1024+p, 223 --------- Love your videos, keep up the good work. Lijep pozdrav!
Is there a graphics package for this version of C? I converted an Atari Basic program to Commodore Basic and the lack of graphics commands in Commodore Basic made it very difficult and slow performing. Of course I could have added multi color, but compared to the Atari's graphic commands, reproducing the bitmapped graphics was much more difficult than it needed to be. With this C, can you specify an X,Y location and plot a point with or without color information?
Nice and simple, but unfortunately with the C64, a simple CPU reset will not get you out of some persistent software. Too long to explain here but it is about how the reset vector is set and simply resetting the CPU will only make it jump to where the programmer wants it to jump. So, some clever people came up with something called "EXROM Reset". It involves using a second line (PLA EXROM pin) and pulling both the CPU reset and the EXROM low, but releasing CPU a little before EXROM. There is a good video here, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OV5tNYhqQ7w.htmlsi=rTxRNl2_RsN0OVai which explains it much better, also check the follow up video on the same subject.
Well, I know that my solution is not perfect, I just wanted to be able to reset c64 using the keyboard (combination of keys) and I managed to do just that. In addition, I was using the stock C64 and never tested my solution with other Kernal ROMs or other sys cartridges. Thank You for the video suggestion and thank You for watching :) Cheers!
I still love the C64 and I used to program it over 30 years ago, but since I despise math I didn't get to advanced stuff. Seeing this code here and all that math makes my stomach turn. But the end result is amazing!
Really nice, and like many others i would have liked to have such a cartridge back in the days. I love your trick at the very end :) thinking that it might have been possible to parse the basic line holding the "*=" directory and dynamically generate the buffer data in the very last line so that one can assemble and run at any memory location. Awesome stuff !
Does this basic assembler lack comment or rem features? If would be useful in these videos. Really useful. You know that tone left on at about 55:05? RunStop Restore fixes sound/noise too.
If you made this Donkey game in 6502 Assembly (a.k.a. Machine Language), then you could get the game's action to REALLY speed up -- to the point where it becomes impossible to avoid hitting the donkeys! This would be a good demonstration of the capabilities of 6502 Assembly. Of course, Donkey in 6502 Assembly would require many more lines of code than the BASIC version; as 6502 Assembly is a very low-level language.
When I did programming on my C--64, I used BASIC a lot, much faster to write software, but I also used assembler a lot too, because BASIC would be way too slow for certain things, so I mixed both, I did BASIC and assembly for some routines and embedded those routines in my BASIC program through the SYS command. I did some pretty impressive and fast BASIC stuff this way - It was very useful for BASIC programs with background stuff, through the use of interrupt routines in assembler.
Oh Yes, that was the thing back then and still is, if You want to speed up some parts of the BASIC code, just inject that part in the memory (machine code) and call it with SYS. And Yes, BASIC couldn't handle interrupts so for that You would need to use assembly/machine code for sure :) Cool! Thank You for watching :)
Well, those numbers are part of a BASIC code. I used Mikro Assembler cartridge so that I could write on C64 and compile and run the assembly code on C64. But, You don't need those numbers if you use some other assembly compiler. You can compile the code on a modern PC and then just run it on C64. For assembly language the labels are important. ...and those labels are converted to memory addresses during the compile process.
@@nagyandras8857 Yes this is where I want to explain how lda and sta instructions work. This is not a good code :) A more efficient way would be to have a loop label on line 20, yes! But also, we have direct instruction if we want to increment by one, just direct "inc $d020". If we want a different increment value then we can use Your suggestion, Yes. Sorry, I didn't get what are you asking the first time :)
19:50 I would probably use JSR $FFE4, then BEQ LOOP. That way you can exit by pressing any key. 31:03 This effect only works on PAL C64s. On NTSC machines, it just displays somewhat random garbage.
Thank You for your information, uuu, ok I need to check what is the problem with 31:03 on NTSC, to be honest, I didn't check if ti works on all systems. Cheers!
I imagine discovering RunStop/Restore is going to change your life. I can't imagine not having that available! It was essential in my experience. ProTip: sharp quick taps on the Restore key. It's weird that speed of tap can make a difference sometimes but it really does. Gotta be in how downside transition of the signal generates the NMI.
@@JosipRetroBits if I just knew this back in the eighties.. those kernel routines are very useful. Back then it was really hard to get this kind of info and explanations. I only changed colors and did some sprites as an teenager in assembly. Could you even imagine what an impact it had if everybody had an assembler and this kind of kernel-routine info back then ..
@@Jemacaza Yes for sure. For comparison, the first time I used C64 was retyping some game from the magazine. I didn't understand anything :) Now it's so much easier to get information and to learn new stuff. And of course, You can develop and test your code on the modern PC before you run it on the real C64 and this much faster and easier way to do this. :)
My first computer had a hex keypad and allowed to enter machine code directly. No assembler needed. A rough start, but after that you are afraid of nothing anymore 🙂
Ha ha, that is awesome :) Oh, those are the first kit comp.? with just a numeric keyboard? Programming in machine code directly, You have my respect, Sir. :)
@@JosipRetroBits Yes, it's a kit from the time when you could not buy a computer in stores yet. A Netronics Elf II. I still used ut until I bought a Atari ST and still have it. You should take a look at the processor (a CDP1802) if you are really interested in 8 bit computers. Not exactly mainstream, more like RISC before that was officially invented.
As an ICT-professional, also very interested in retro-computing, I see many videos about different computer & network stuff on youtube and other media. I must say that this one is amazing. You explain this in a professional way. Lots of video's have lots of hesitating as if the teacher sees what appears on his screen for the first time. Not in your case. You master the knowledge perfectly. This video gave me lots of ideas and teached me stuff I was looking for. Thank you very much.
Thank You very much :) Just to be clear, there are people in the retro community who have more knowledge and teaching capabilities than I do. I wish You the very best in Your retro journey and welcome aboard :) Cheers!
I suggest that you check your facts before offering such bombastic corrections. On the C64 it is and always has been spelled KERNAL. en.wikipedia.org/wiki/KERNAL
@@Joel-qz6sd Yes, a bit more than that. but in general Yes. Kernal is simply an operating system on Commodore 64. It also takes care of all other operations on the system, like cursor, serial communication, time, etc.
You have to turn off the computer just to get out of that 4096 loop? Why won't the stop/restore key combo work, even though I've seen it stop plenty of ML programs before, without your having to look for a press of "stop" or "stop/restore"?
Run/Stop key will not stop ML execution only execution of BASIC code. That is why I needed to implement STOP key detection to exit the program in my examples. Thank You for watching :) Cheers!
Haha, wow, interesting way to write an ML assembly: using a BASIC listing as your playground (but then still having to have the underlying programmer assemble it).
Yes, back then this was a very nice way to program/develop in assembly and compile/run on the same machine. Now it's way better to develop on a modern pc and then just test on C64, but I like this first method, don't know why, feels natural :) Thank You for watching :) Cheers!
21:12 there is a bad edit about PAL jiffy timing. Can't tell if you are saying is same 60Hz for PAL or 50Hz. I would read the text description onscreen but your PIP narration window blocks it.
It is the same on PAL and NTSC machines, 1/60th of a second. (60 times per second) Sorry, maybe I didn't explain that very well in the video :) Thank You for watching, Cheers!
Back in the day we were relying on books, and I think there wasn't a book that had all these routines printed correct, either missed a whole page or printed a different page instead, also I had so many bookmarks in those books to find all the routines again 🤷♂ I still have the Commodore related books in between the newer computer language books 😅
Yes, it is much easier today, and most of it has been well documented and disassembled so that we now "know" a lot more. I don't have many Commodore books but I never saw any routines explained anywhere in those books. Memory addresses Yes, but not routines. Thank You very much for watching :) Cheers!
Hi, not with machine code (assembly code). That only works with BASIC code. But I've implemented that option later in the video. Thank You for watching :)
@@JosipRetroBits that's weird because l remember RunStop/Restore working for ML unless it was specifically disabled. Hold down RunStop while you sharply tap RESTORE several times. I know the C64 needs a rapid transition on the restore key- usually several. Why, l don't know. But slow wrists were less successful. I suppose this could be a Mandela memory Effect since l haven't tried this is decades. But l could swear this triggered an interrupt that sends you back to the ready prompt. Try it and let me know.
@@saganandroid4175: Yeah, that's what I remember as well. I wonder why he never bothered to try it. I have just set my 128/64 back up and I have just re-encountered ones that have _disabled_ the restore key for exiting; and in fact, they restart the programs instead; and you can even soft-reset from 64 back into 128, run something there, and then soft-reset or go64 back into 64 and that program immediately restarts! BUT... if I remember right, it had to be specifically programmed to do that; otherwise what you were saying would indeed happen. I'll have to go through my disks and make a count list of some sort to see if we're right: which is the exception or the rule. And yeah, on an original 64 you do have to hit "restore" fairly hard. I don't know about the C, but on the 128 in either mode you don't. Why don't you set your 64 back up now too?
@@JosipRetroBits try it. Run your ML code. Hold down RunStop and nothing happens. Now while holding that key down, sharply smack the Restore key several times. That should generate a NMI. But on most C64s you need a quick sharp wrist action on the Restore key because only the trailing edge of that line is useful. Try it and report back.
@@JosipRetroBits Great video. I had a Commodore 16 in 1985. My classmate had a Commodore 64. Any idea where I can find the user's manual. There were very good Basic codes in that book.
Really interesting stuff! One thing though: At 45:02 ... What is the reason for EOR $d012 and not simply LDA $d012 ? Am i missing something vital here?
@@JosipRetroBits But the accumulator will always have the same value (255 / $ff) on each iteration due to your JSR to $FFE1, so I cannot see how that would increase randomness. Try adding STA $d020 in line 22 and you will see what I mean.
