Omegamatrix
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Everything posted by Omegamatrix
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You're right. This part of the code looks straight forward. So really the magic is in the pattern of numbers from the pseudo random generator, and how that corresponds to D7 and D0. I have not looked at the rest of the code at all, but I am wondering if this random generator is only called for this routine? It would be more interesting if it wasn't. If it is not called only by this routine I would want to know if it is called every nth time, repeatedly. -
asl Value+1 asl Value bcc .finish inc Value+1 .finish:
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Hmmmm. I feel the conspiracy theories have already started Mr Davie, or should I say Andrew Shay! 🙈🙉🙊
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I played this a lot as a kid on the Colecovision, and gave the 2600 version a go. At first it seemed very stripped down, but after playing it for a while I started to enjoy it a more. What do you all think of 2600 Venture?
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You shouldn't strobe HMCLR immediately after HMOVE. You should leave the HMxx and RESxx registers alone after HMOVE for a certain amount of cycles. I forget how many exactly but it was ~ 24 or so. Now there are times that you don't do that for trickery, but for normal positioning you leave them alone. Also, if you are using a 48 pixel display routine then you also have to adjust when you update GRP0 and GRP1 inside of it.
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What's the count of games AA is displaying at PRGE?
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It's never done, but you reach a point where you have to cut off and just look for bugs. I think I'm there... 🎃
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That box is beautiful. The colors are really pleasing. Great job!
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Up Up Down Down Left Right Left Right B A Start...
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What's an Ad? Is it one of those App thingamajigs? I'm still trying to catch up with this internet fad....
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Gentlemen, we can rebuild it. We have the technology. It shall be reloaded, made better than it was before...
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The difference between starting a game and finishing a game? All the stuff in-between...
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What is a game but a bunch of 1's and 0's? A child could do that...
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It's alive. My God, what did I create......
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I've reached 36 characters, but if you want simple re-usable on stock hardware then I would stick with Eshu's 32 character routine. Interestingly enough ZackAttack worked out a full 160 pixel bitmap using bus stuffing. I proved it out with a non-bus stuffing test rom that turned a single pixel off at a time using his routine. IMHO Zack's 160 pixel bitmap was the #1 technical achievement for the 2600 in 2018.
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I think the last solution might be optimal. I would love to see some other ideas though. One thing I should mention is that I don't trust ASR anymore. I had problems with it before on an Jr. Otherwise it would be a quick way to save 2 cycles and 1 byte to just ASR #$F0. It is actually would be a very useful opcode if it was stable. Others have also noted the same problems that I had with ASR.
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Went with 2 temps instead of a single temp and and an index register. This version saves 1 byte and 3 cycles over the BCDtoBin4 routine in post #5 above. ; BCD value $0 - $99 is in A. Returns binary number 0-99 in A BCDtoBin6: sta Temp and #$F0 lsr sta Temp2 lsr lsr adc Temp sec sbc Temp2 rts
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I'll post a table version. It is 5 cycles faster than the last version, but uses 6 bytes more. It is only useful if you need the speed. ; BCD value $0 - $99 is in A. Returns binary number 0-99 in A BCDtoBin5: tax lsr lsr lsr lsr tay txa sec sbc SixTable,Y rts SixTable: .byte 6*0 .byte 6*1 .byte 6*2 .byte 6*3 .byte 6*4 .byte 6*5 .byte 6*6 .byte 6*7 .byte 6*8 .byte 6*9
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One cycle faster, one byte less... ; BCD value $0 - $99 is in A. Returns binary number 0-99 in A BCDtoBin4: tax and #$F0 lsr lsr sta Temp txa sec sbc Temp rol sbc Temp lsr rts
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I had a thought, and made a new routine. It is 2 cycles faster, and 2 bytes less than the previous. tax and #$F0 lsr lsr sta Temp lsr adc Temp sta Temp txa sec sbc Temp rts In one byte BCD number the high nibble is a base 10 value stored as a base 16. To convert subtract a value of 6 * (high nibble >> 4) from the original value.
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Nice! So it is a new bankswitching then. If I read your post correctly then the roms the original poster had for Fathon was correct, but Mickey needs the banks reversed?
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It's always awesome to see a new game. I feel it was absolutely appropriate to have the author's name in the title screen. Thank you to the efforts of all, including Mr. Tokar. 🎂
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Well that is good to know. I wouldn't have depended on the SP being at $FD for a normal game, but I did with the 32 byte demos we did last year
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Jentzsch/Davie '2600 tile/character graphics engine
Omegamatrix replied to Andrew Davie's topic in Atari 2600 Programming
I appreciate your efforts! If you hadn't made the fixes then probably nobody would have...
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