Re: Question on ProDOS's BASIC.SYSTEM

[Don Bruder <dakidd@sonic.net>]

In article <cqik45$4ef$1@ottoman.cs.fiu.edu>,
 Zorin the Lynx <yakko@zorin.org> wrote:

> A recent thread on BASIC.SYSTEM got me wondering...
> 
> Does BASIC.SYSTEM in ProDOS completely replace the version of Applesoft 
> in the Apple II's ROM, instead of just adding hooks to the existing 
> BASIC like DOS 3.3 does?
> 
> If it does completely replace ROM BASIC, doesn't this use up extra 
> memory unnecessarily? You would think the DOS 3.3 way is more efficient.

I'd estimate 99% of BASIC.SYSTEM to be nothing but glue code to connect 
the ROM-based AppleSoft to the ProDOS MLI, with the other 1% being 
patches to fix the ROMM Applesoft bugs and add a couple of commands that 
AppleSoft/DOS never had. It seems to me that something about the "&" and 
CALL commands got changed (My fading memory is suggesting that it was 
something to do with diddling the way registers were set up) and I think 
there was one other command that got patched (but I don't remember which 
it was - It's been too long), and there were a couple of "new toys" (The 
"-"  As in "-someprogram") that got added, but otherwise, the ROM code 
dealt with the actual "heavy lifting" of editing/parsing/executing the 
BASIC language. If the program didn't involve disk access (or other 
functionality provided by ProDOS) the ROM was in charge all the way. If 
disk access or other ops that needed the support of ProDOS were used, 
BASIC.SYSTEM served as the glue betwen the ROM code and the ProDOS MLI, 
but was otherwise essentially inert.

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