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I have tried to unroll the loop that does the 191 'normal' lines and that way I can gain a 7,4% (only) at the cost of having an executable that is 5.500 bytes instead of the just 185 bytes of previous version :( Here you can found the source file ... not many changes, just macros cheers pere VSCROLD...

I have modified the 'cleaning method' for the first line Not that important because it is one over 192 processed lines, so just a very little speed gain The cycle-count for 1st version was: 60 (Intro) + 156 (1st Line) + 134 * 191 Lines + 84 (change of buffer) = 25.894 cycles For this last version, i...

for sure this will not be the last version, but works faster than previous ones Thanks a lot, Ciaran and Stew opt cd opt ct org $4500 ; donde ubicar el programa inicio sts $0114 tfr cc,a tfr dp,b std CcDp orcc #$50 ; deshabilita interrupciones lda #$4 ; poner a uno los bits 0 y 2 sta $ff03 ; para de...

Hi Stew, I think that I answered too fast! I need to synchronize the changes of images exactly when an FS arrives (end of screen) That interrupt will occur even with IRQ and FIRQ disabled, but you talk about disabling them in the PIAs. If I do this: lda #$04 ; reset bits 0 and 1 sta $ff03 ; FS IRQ t...

Hi Pere, You can make it go even faster if you use both stacks. Sixxie's suggestion was to disable interrupts in the pias and make use of cc & dp as well, i.e. something like this to move the screen up one line: ldu #copy_from_address lds #copy_to_address+8 ; repeat these 3 instructions many times ...

@Ciaran and Stew Now I remember the reason why I forgot about the stack ... a) working right on the visible screen produces noticiable glitches b) using double buffer, screens have their beginning at $c00 and $2400 and the data is copied once forwards, next backwards and so on. The stack has to be c...

Just to echo what sixxie is saying: Stack ops do give a big speed up and "Four buffer copy horizontal scroll (exploding heart?) technique" gives amazing results but some sort of compromise is required to keep the memory use practical. e.g. drop the resolution to PMODE1, or have a smaller play area ...

Yeah horizontal will always be slower. Unless you maintain four buffers (shifted 0, 2, 4, 6 pixels), then you can use byte aligned operations. Lots of RAM used though! Are you using stack ops for your vertical scrolls? You can save a lot of cycles that way. With interrupts disabled on the PIAs, you...

Hi Stew, thanks a lot. I will try both methods. These are simple examples for a friend from Retrowiki that asked me to create some kind of scrolling routine for the Dragon. Probably he is willing to create a a game! The vertical are faster (double) than the horizontal despite they move 192 lines whi...

Hi Stew, I am attaching here an VDK I have compiled for spanish friends at the RetroWiki web It contains scrolls for PMODE3 full screen in these types: left normal and cycling right both ways up both ways down both ways With RUN"TESTALL" you can choose any of them ... Finally there is another bas to...