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Showing results for tags 'kernal'.
Currently, memtop allows the top installed bank to be read/updated. You read memtop, and write back with needed banks subtracted from the available count. This allows a program to allocate banks "off-the-top" If this ability were available in membot, banks could be allocated from low banks. This would allow the kernal and geos (or other system software) to allocate banks for their own usage and applications would not have to guess how many banks they need to skip off the low end. By default, the first free bank would be 1. Updated to 10 if geos needed space.
On the C64 we could clear line X on the screen using a poke and sys to a kernal function. POKE 781,X: SYS 59903 Is there something like this for the X16? If I try it, it simply clears the entire screen. What I am doing is printing a game "shopping list" using CHR$(!13) CHR$($11) CHR$($11) so in the middle of the screen is a table of items. Then I'm using CHR$($13) to send the cursor back to home and prompt what the player would like to buy. The 2nd line would say if they purchased it, didn't have enough money, etc. Then I was hoping to clear just the 2nd line on the screen and re-prompt them until they leave the store. Any pointers would be cool.
Hey all, First attempt at getting some text on the screen in 6502. I notice inconsistencies between the Programmers Reference Guide and some of Matt H.'s videos. Example: CHROUT = $FEDE or $FFD2 CHRIN = $FEE1 or $FFCF I've seen 2 values for each of these. I've also seen both values in the videos. In the videos there's mention of PLOT, SCREEN, clear screen and GETIN, and none of these seem to exist in the Programmers Reference Guide. Do those kernal routines exist still? I hope so. Also, any attempt I make to display characters results in garbage characters. See sample assembly below. Using: cl65 -t cx16 -o HELLOWORLD.PRG -l listing.map *.asm ./x16emu_mac-r38/x16emu -prg helloworld.PRG I also notice that in memory, the "Hello" appears as ?ELLO, which is peculiar, making me suspect it doesn't know about PETSCI? Thanks for any help, Fippy
I wrote these from scratch. I want to write them without ever seeing the actual kernal. Easy-sounding ones first. How close are these routines to being correct? I'm a kernal virgin. Michael's pagetable site has the commentaries. I might be misusing opcodes. Error and boundary conditions might need handling. MEMBOT is virtually identical to MEMTOP. SETTIM and RDTIM. I think I'm going off the rails here with the indirect loading. Now I'm thinking these are all direct, which would greatly shrink the code... In for a penny, in for a pound. Here's UPTIM, and I suspect there's edge cases here I'm not seeing. And SCREEN and PLOT.