At 09:44 AM 3/8/99 -0300, you wrote:
>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.
Most games use LD (nnnn),A for all switching. In that case, you only have
to look for #32 #00 #xx, where #xx is in a set of page switch addresses
(example of such a set: { #50, #70, #90, #A0 } ).
>> 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!
Although Konami does frequent slot switching, not all pages are visited
frequently. Most of those cracks run at a reasonable speed, with the
exception of Firebird, which slows down a lot at certain points.
>> >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.
You cannot write those two bytes at that address. But you can read them.
And you can write them at other addresses (#5FFE-#5FFF, #9FFE-#9FFF,
#BFFE-#BFFF), you're using pages after all.
One advantage of ESE-SCC access over MegaRAM is that you can have more than
one in your MSX. This is good if you for example have a MegaSCSI and an
ESE-SCC in the same MSX.
>> 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?
Look at my page and download the DSK version:
http://www.stack.nl/~mth/msx/solideng/
>> 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!
Is that necessary? Can't you call #4010 in the diskROM slot? Most of the
data structures below #F380 are only necessary if you load files. If you
stick to sectors, the game can overwrite them. This is the reason why the
Solid Snake crack saves to sectors, while the original saves to files.
Bye,
Maarten
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