On Thu, 25 Nov 2004, Cameron Kaiser wrote:
> > > 10 HOME
> > > 20 GOTO 10
> > >
> > > Where do I send my mailing address? ;)
> >
> > There was no HOME command in the original Apple-1 BASIC. The screen was
> > not memory-mapped. You would have to print enough carriage returns (16 I
> > believe) to push every line of text off the screen to clear it.
>
> This is almost on-topic now ^_^
>
> Could you do a CALL -151 to achieve the same effect? I think that was the
> clear screen for Integer BASIC (or maybe it was CALL -868 ... I forget).
CALL -151 was the command to return to the monitor from BASIC in the Apple
][ integer BASIC. I'm pretty sure location -151 did not map properly on
the Apple-1 since the monitor ROM was so completely different between the
I and ][.
CALL -868 was to clear the screen, but again that was on the Apple ][
which had a much expanded monitor ROM and some tools in ROM. The routine
at -868 actually stored ASCII 32 to all the locations in the memory mapped
screen, something the Apple-1 didn't have.
--
Sellam Ismail Vintage Computer Festival
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Received on Fri Nov 26 2004 - 05:07:16 GMT