On Thu, 11 Mar 1999, Maarten ter Huurne wrote:
> At 09:56 AM 3/11/99 -0300, you wrote:
>
> [Solid Snake]
> >> The 256K version is without sound however, so it is not equal to the 512K
> >> version.
> >
> >Why this conversion cut the sound? Did it cut the PSG sound?
>
> All sound.
> Sound data for MG2 is quite large (about 80K). Although not all songs are
> necessary at the same time, the least that is necessary is the replayer,
> the current song and most sound effects. Not cutting sound in the 256K
> version must have been close to impossible.
Using a 720kb disk, wasn't possible to use more 8kb blocks than the
original number?
> >> And why don't use DISKROM?
> >
> >Because there are 2 problems: the high memory area is destroyed by the
> >game variables, and I couldn't use the page 0 to save them (making a
> >memory swap) because the latest Konami games also uses the page 0 to store
> >variables. The other problem is simultaneously high speed disk access and
> >copy protection.
>
> As I wrote in another reply, most of the high memory area is only used by
> the diskROM if you're accessing files. When you do sector access, even
> through the diskROM, much less high memory is reserved.
That's true, but the area above EFxx is still used in sector transfers.
And the most part of Megarom games that don't disk access does use memory
until F380.
After I had debugged the TR diskrom, I discovered that area F1AF is
essential to read/write sectors, and EB95 is the common area to transfer
any kind of data in several kinds of disk interfaces.
> By the way, there are copy protections that can be checked by using only
> the diskROM. For example, the protection used by Sunrise, which is actually
> an adapted version of MicroCabin's protection.
My conversion of R-TYPE to run in Megaram + VRAM (MSX2) does use a similar
technique. But it's veeeeery slow!
Greetings from Brazil!
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