From: Ullrich von Bassewitz (uz_at_musoftware.de)
Date: 2008-03-18 20:50:39
Hi!
On Tue, Mar 18, 2008 at 03:08:10PM +0100, ruud.baltissen@apg.nl wrote:
> Can you tell us what you did? No need then for others to invent the
> wheel twice :)
There were full instructions on how to do it in the first release of "Heute
schon geused?!". I will have to dig it out and scan it. Simply stated, the
high address lines that go to the PLA are shifted, so that the PLA does no
longer generate a 64KB select signal for the DRAMs but a select signal for
256KB blocks. A multiplexer must be added to generate the additional address
signal for the RAMs.
> How long? Then I have an idea when it is time to start worrying.
If I remember correctly, it was about 40 seconds. Take the time for the
startup of an unexpanded 610 and multiply by 8.
> Just an idea: if one compares both ROMs and can explain the differences,
> it may be possible to addapt them to 1 MB.
It's not as easy as that. The 620 basic utilizes the 4 segments for different
purposes. It stores strings into one segment, arrays into another and so
forth. But there is nothing that uses more than one segment to store one type
of data.
Maybe that's also a good thing. Debugging 900KB of BASIC spaghetti code is
more than just a nightmare:-)
Regards
Uz
--
Ullrich von Bassewitz uz@musoftware.de
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