Re: Apple IIplus ROMs in original II?

[Roger Johnstone <rojaws@orcon.net.nz>]

In <qhk6oaj5iy.fsf@ruckus.brouhaha.com> Eric Smith  wrote:
> Paul Schlyter <pausch.NO@SPAM.saaf.se> writes:
>> ProDos won't boot on an Apple II with Integer Basic ROM's on the 
>> motherboard.  And an Integer Basic ROM card won't help either since 
>> it cannot coexist with a Language Card, and ProDos requires a 
>> Language Card  to be able to even boot.
> 
> The earliest version of ProDOS that I ever had was able to boot on 48K
> Apples with no language card and with either Integer BASIC or 
> Applesoft ROMs, though it couldn't run Applesoft programs unless you 
> had the Applesoft ROM, and it didn't have any support for Integer 
> BASIC.
>
> That may have been a prerelease version.  If any official release 
> would have been able to do that, it would have been 1.0.  But I don't 
> know whether 1.0 will do that or not, and all of my old Apple II disks 
> were lost in a move in 1988.
>
> Eric

ProDOS 1.0 will run fine on a 48KB Apple II. If it's booted on a 48KB 
machine ProDOS loads into the top of main memory, just like DOS does. On 
a 64KB machine it loads into the 16KB language card area instead, 
leaving most of the main memory free. However support for 48KB machines 
was dropped with ProDOS 1.1 and very few ProDOS applications will work 
on a 48KB machine. Most of them require too much memory, or even if they 
would fit they don't bother checking if the memory is free and just 
assume ProDOS is in the language card. One of the few programs that does 
work is MousePaint.

A seperate issue is support for BASIC. BASIC.System doesn't have any 
code to relocate it in memory so it always loads into the top of main 
memory, which only works if ProDOS is in the language card, and it 
relies on AppleSoft BASIC being in ROM. So running BASIC programs 
requires a 64KB Apple II+ or later, or a II with AppleSoft ROMs fitted.

If someone at Apple had really wanted to they could have made a version 
of BASIC.System that could be relocated in memory and didn't rely on 
BASIC in ROM, but on a 48KB machine after loading ProDOS, AppleSoft 
BASIC and BASIC.System you would only have about 14KB of free memory!

-- 
Roger Johnstone, Invercargill, New Zealand
http://vintageware.orcon.net.nz/
________________________________________________________________________
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