So I'm tinkering around and compiling MS BASIC for different platforms.

https://github.com/mist64/msbasic
http://www.pagetable.com/?p=46

When I get to the Apple platform, I get an error. (using ca65)



The output is:



In my "defines_apple.s" I have:



So since $0200 = 512 decimal, this should be OK. But from the error you can see it is not.

In a previous attempt, I would just add " + 256" to the problem to fix the "-1" error. But I don't really think that is a fix.

I get how +256 causes the value to roll over. But, *WHY* is that needed?

I guess where I'm confused is why it was done like that at all. I wonder how much of that source code is actually from Microsoft vs. a de-compile of a ROM file.

Any information is appreciated.

_________________
Cat; the other white meat.

Try adding some parantheses

_________________
Andrew Jacobs
6502 & PIC Stuff - http://www.obelisk.me.uk/
Cross-Platform 6502/65C02/65816 Macro Assembler - http://www.obelisk.me.uk/dev65/
Open Source Projects - https://github.com/andrew-jacobs

That should work. The problem is that ca65 assigns the "<" operator a higher precedence than "-", so "<inputbuffer" is "<$0200", which is zero. Zero minus one is minus one.

You could also assign the value "inputbuffer-1" to a symbol and use that symbol instead (ie., "<symbol", ">symbol").

That worked!

Thanks!


I believe ca65 just doesn't like negative numbers like the following:



So adding "+ 256" fixes those as well.

It's pretty amazing to be able to create seven different versions of MS BASIC for these platforms.

I've been organizing the code a bit..separating out the platforms, etc.

Now that's working, the next move is to test out one of these BASIC's on a real computer.

Next, start working on my own version for my SBC. Heck, it might be fun to make another version for the L-Star.

@Jac, you interested?

Thanks!

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Cat; the other white meat.

The OSI emulator for L-Star already runs Microsoft Basic, and the KimStar project can be used to run Microsoft Basic (a different version) on a MicroKim. I think OSI Basic is one of the oldest MS-Basics you can build, and there are known bugs that were fixed later. But it does fit in 8K ROM. The Basic for the KIM-1 (and many other variants) needed 9 KB of ROM space IIRC. Obviously for the L-Star it doesn't make much of a difference

My Github contains an "AppleSoftBasic.rom.bin" but I forgot where I got that (edit: it's probably the version that Vince Briel put into the latest versions of the Replica 1, see here and here). AppleSoft Basic for the Apple II was a rebranded version of Microsoft Basic, and is also one of the possible build targets of the MS Basic source code.

Sooo... I guess you've set yourself a task and it's already done

===Jac