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I'd like to introduce my latest project: Altirra Extended BASIC, a Turbo-Basic XL compatible interpreter implemented in a banked MaxFlash 1Mbit cartridge. Often when I need to do testing on the physical hardware I just end up using BASIC when the speed and control of assembly isn't needed, as I can just type in the program instead of hooking up the tether to upload one. Problem is, Atari BASIC is missing useful features like hex values, and the Altirra BASIC cartridge is packed like a can of sardines, so I couldn't add anything substantial there. Thus, the idea came to take Altirra BASIC and split it across cartridge banks so that it could be expanded. At the same time, experience had shown that much of the BASIC XL subset wasn't that useful due to the small pool of people who had used it and could run it, but with the extra space I could implement a far more expansive and available language: Turbo-Basic XL. Therefore, once I had gotten the interpreter reorganized into a banked cart, it was then possible to begin reversing TBXL's token format and reimplementing the extended language. Details: Uses a MaxFlash 1Mbit (128KB) cartridge. I chose this cartridge type because of its address-based banking mechanism, which turned out to be faster than data-based banking. Figuring out a usable long jump mechanism was a big obstable to getting this off the ground. Also, I have one of these carts and it's fairly widely emulated in the mega-carts. Currently 7 8K banks are used, 6 of which are split with a 4K shared bank and a 4K variable bank, and the last one being a special full bank for the help system. Half the cartridge is thus currently unused. Unlike Turbo-Basic XL, Altirra Extended BASIC does not occupy memory at MEMLO or memory under the OS ROM. This means that its memory layout is closer to Atari BASIC and it will run on a 400/800, even with 16K. Some TBXL programs are incompatible because they hardcode addresses in the $A000-BFFF range which Altirra Extended BASIC occupies. ATXBasic is binary compatible with Turbo-Basic XL 1.5 save files. However, this means that it is not binary compatible with Altirra BASIC's BASIC XL subset. Conflicting token values, couldn't do both. Some statements like LOMEM have been relocated to new token values above TBXL's. The AltirraOS math routines have been hoisted into the cartridge and reworked for speed. They are not necessarily as fast as TBXL's yet -- haven't touched division or transcendentals yet -- but it should be in competitive range overall. The OS math pack is not used so results are consistent between OSes. I implemented as much of the Turbo-Basic XL language as I could find documented or tokens for, and tried to match TBXL's behavior when it diverged from Atari BASIC, such as the ON statement. One deliberate incompatibility: TIME$ uses the accurate frame rates for NTSC and PAL, no way I was going to use hardcoded 50.0Hz. There is also a built-in help system, which I plan to fill out QBasic-style -- mainly because I am tired of turning away from the Atari to look up OS and hardware addresses. Writing the help directly is a pain, though, so it only has two pages right now. Need to write a help compiler. Preliminary docs are attached, though I still need to edit some old stuff from Altirra BASIC that needs to be changed. All that being said, I could use help testing the TBXL subset. I have a large collection of Atari BASIC programs and have already gotten my classic test suite working (Nazz, SpyPlane, Quadrato, Escape from Epsilon, Valiant, Jenny of the Prairie, etc.) but I have very few TBXL programs. I'd like to get the TBXL subset more solid before jumping into more optimizations or adding more commands, and with Altirra BASIC the community was very good at pointing stuff I didn't know about Atari BASIC. One lengthy TBXL program I've gotten running is Rocket Rescue -- that was fun to fix (PAINT leaks, ugh). atxbasic.bin atxbasic.pdf