Closed johanberntsson closed 3 years ago
neilsf
commented
3 years ago Hi. Thanks for your feedback! The problem is that we need to make sure that there's a zero byte at $0800 otherwise a C64 system will refuse to run the program. What does the MEGA65 emulator check exactly? Maybe there's a way to fulfill both system's requirements. Please note however that only the C64 is supported right now. Thanks.
johanberntsson
commented
3 years ago The emulator opens the prg file and checks the first two bytes. If they are 01 and 08 then it is assumed to be a C64 file and started in C64 mode. I solved the problem for myself by generating the asm code, and then using a script to replace ORG $0800 HEX 00 with ORG $0801 before calling dasm to compile the prg. This prg can then be used both on the C64 and MEGA65. I don't think you need the padding byte, at least in the normal case where the C64 will be initiated with a 00 in $0800 at reset/startup. If you create a basic program and save it on a real C64 the file will also start with 01 08.
neilsf
commented
3 years ago Okay, if it is safe to assume there's already a 00 byte at $0800 then I can change the start address and omit the 00 byte.
johanberntsson
commented
3 years ago It is definitely safe. As mentioned, this is how basic files are saved and used on the original hardware.
neilsf
commented
3 years ago Please try the latest release: https://github.com/neilsf/XC-BASIC/releases/tag/v2.3.12
johanberntsson
commented
3 years ago Excellent, the new release solves the problem and everything looks fine. Thanks for your quick response
The two first bytes of the generated PRG files are not 00 08, telling the C64 that the file should be loaded at $0800 when loading with ,8,1. This is incorrect and should be $0801. This creates problems when trying it on the new MEGA65 emulator xemu-xmega65, which checks these bytes to detect if the PRG file is generated for its C64 or C65 mode. Please change so that $0801 is used.