Never mind! I only meant it is on 16kb basis and can be paged to 49152-65535. As long as a game don't use memory mirroring and secon screen bank, it is usable to simulate 128k, since you only need to change some out's. Just go, find "out" instructions in the program, and you are done.
When converting 128k games to normal Sam, you need to solve the problem that Sam is switching 32768-65535 at once, while ZX programs usually use 32768-49151 for static program and 49152-65535 for other data. ----- Original Message ----- From: David Ledbury <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, August 03, 2001 10:40 PM Subject: Re: External memory on Sam > No - can't use it for ZX128 paging - as SAM's is rather different layout > > > ----- Original Message ----- > From: "Aley Keprt" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Friday, August 03, 2001 11:22 AM > Subject: Re: External memory on Sam > > > > It is a great piece of hardware. > > Similar to Amiga. Only CPU access, but well pageable, usable to achieve > 6MHz > > speed, and allows to emulatoe ZX Spectrum 128 paging. Am I right. > > > > Master Dos seems to use it for its own. > > > > That is probably what I talked about recently. Simon Cooke wrote that I am > > missing the point, when wanting this from 80's designed computer Sam > Coupe. > > But here I can see it is real. So why don't we have at least 256KB > internal > > memory made of this external one? > > > > ------------------------------------------------------------------ > > Bc.Aley [eili] Keprt - games & multimedia programmer > > ICQ: 82357182 (evenings) *** phone: +420-68-5387035 (weekends) > > private e-mail: [EMAIL PROTECTED] *** http://get.to/aley > > office: Illusion Softworks, Brno, CZ - [EMAIL PROTECTED] > > ------------------------------------------------------------------ > > > > ----- Original Message ----- > > From: "Simon Owen" <[EMAIL PROTECTED]> > > To: <[email protected]> > > Sent: 3. srpna 2001 12:02 > > Subject: RE: External memory on Sam > > > > > > > Aley Keprt wrote: > > > > Is external memory contended? > > > > > > Nope. > > > > > > > > > > Or how does it work? Is it possible to page it into 64KB CPU > > > > space, and then let CPU run at 6MHz in there? > > > > > > Well, it can only be mapped into the upper 32K, not the full 64K address > > > space (still be good enough for a lot of stuff). Depends whether you > > > were thinking about general programs using it, or getting the BASIC > > > system to use external memory instead of contended system RAM. The > > > display will always be in system RAM, so you'd have to write to it in > > > the border area to escape as much contention as possible! > > > > > > Not many people have external RAM though, so I can't imagine any > > > existing software would/could rely on it for the extra speed. It'd > > > certainly screw up fancy demo timings too! > > > > > > Si > > > > > > > > > >
