On Sat, 6 Mar 1999, Maarten ter Huurne wrote:
> What I had in mind as "semi-automatic" is less automatic than your
> approach. It would locate all LD (x000h),A instructions, dump the bytes
> around it to your screen and then ask you "modify yes/no?". Usually, by
> looking at the bytes surrounding the "32 00 x0", it's easy to judge whether
> it's code or data.
All right, if there's programmer's intervention, then everything should be
right! Sometime ago, I tried something like that, but I couldn't detect
when a LD (16-bit register),A or LD (address),another 8-bit register was a
block switching. And I think that this hindered some adaptations to run
directly on disk.
> >BTW, Konami MegaROM games couldn't be converted anyhow, because they do
> >frequent block switching, what can't be done directly from the disk.
>
> I have seen some cracks that used the upper 64K of VRAM to store blocks
> when they were not used. Many older Konami MegaROMs use only 64K of VRAM
> (or 16K if they're MSX1 games).
I have one of these cracks: R-TYPE. But I don't like this kind of
convertion, because it's a MSX1 game that demands a MSX2 or superior to
run! And here in Brazil, there is still a lot of MSX1 working.
> But many of those 128K cracks had bugs (Vampire Killer, King's Valley) or
> slowdowns (Firebird). I think Maze of Galious did run fine, though.
Konami games cracked to run using high part of VRAM??? This should be very
slow!
> >I would like to know more technical details about ESE-SCC, like: how to
> >switch between "block select mode" and "write enable mode".
>
> By writing to a certain bit.
> >From memory (could be incorrect), it's #7FFE, bit 4.
> In "write enable mode" you can access the SRAM like normal RAM (except for
> address #7FFE and #7FFF). Page switching does not occur if you write at
> #5000, #7000 etc.
> In "block select mode" it behaves as ROM and you can select pages as usual.
Then, the blocks selected on area 6000h-7FFFh have 2 bytes lost? I think
that the solution adopted in MegaRAM is a bit more intelligent.
> >Here in Brazil, a guy whose name we don't know had made a conversion of
> >Nemesis I to run directly from disk, without any memory expansion! But
> >Nemesis I does frequent block switching, and how did he made this
> >conversion? You wouldn't believe, but he reconstructed the entire game,
> >joining the routines that were most frequently accessed, reducing the
> >block switching rate at a minimum!!!!! But, he spent 8 months in this
> >work. Of course, no other Konami games were converted in Brazil.
>
> Impressive!
> Konami also did such a thing, on Game Collection 3, but ofcourse they had
> the source codes available to them, making it a lot easier.
Yes, much more easier. I think that the guy that had made the conversion
could have done more conversions (because the Konami tricks had became
known to him), but he had given up because of software piracy. :-(
> Martos did a lot of re-arranging on Solid Snake. He made a kind of
> mini-BIOS, so that game routines could be fitted into #0000-#3FFF area.
Wow! This is very interesting!!! Where can I get a copy of it? Perhaps I
could use his arrangement to run directly from disk. Did he achieve this?
> >BTW, the Nemesis conversion and my MegaROM games conversions (like
> >Super Laydock, Final Zone, Fantasy Zone, Mirai and Young Sherlock) uses
> >direct access to the port based FDC, then, it won't work on European MSX.
> >Sorry! Perhaps, in future, if somebody is interested, I can make a version
> >for the address bades FDC.
>
> Not all address based FDCs are equal. The one in the Philips machines is
> similar to the one in the SONY machines, but for example the turbo R FDC is
> very different.
I already know. I would have to make a different version designed for each
machine that has a different FDC. Hard work!
Greetings from Brazil!
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Marco Antonio Simon Dal Poz http://www.lsi.usp.br/~mdalpoz
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