RE: Memory Mapper mirror effect?
-Original Message- From: Laurens Holst [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, September 16, 1998 8:52 PM To: [EMAIL PROTECTED] Subject: Re: Memory Mapper mirror effect? Anyone knows if there are memory mappers with mirror effect (i.e., for example, a 128k mapper (8 pages), if I select page 16, I'll get page 8). I don't know any, but maybe there is... All mappers do this 'mirroring'... If they didn't then it would not be possible to detect the mappersize... (only legal mappersize-detection is done by using the mirror-effect). It would be possible if selecting a page that doesn't exist results in selecting memory that is not present. Then data written to an address in that page can not be read back. In fact. it would be simpler then: 10 i=0 20 out hfe,i:d=peek(h8000):pokeh8000,d xor 255 30 if peek(h8000)d xor 255 then 100 40 pokeh8000,d 50 if peek(h8000)d then 100 60 i=i+1:if i=256 then 100 70 goto 20 100 print i;:print " pages of mapper RAM" Well, something like this... Greetz, Patrick MSX Mailinglist. To unsubscribe, send an email to [EMAIL PROTECTED] and put in the body (not subject) "unsubscribe msx [EMAIL PROTECTED]" (without the quotes :-) Problems? contact [EMAIL PROTECTED] (www.stack.nl/~wiebe/mailinglist/)
Re: Memory Mapper mirror effect?
Anyone knows if there are memory mappers with mirror effect (i.e., for example, a 128k mapper (8 pages), if I select page 16, I'll get page 8). I don't know any, but maybe there is... All mappers do this 'mirroring'... If they didn't then it would not be possible to detect the mappersize... (only legal mappersize-detection is done by using the mirror-effect). No! This is not the correct way to detect the mapper size!!! As a matter of fact, the turbo-R does not have 2^x mapper pages accessible when running in R800-dram mode!!! 4 pages are reserved to store bios, basic and kanji (thought these were the ones) in to speed up the execution, because ROM is not as fast as RAM. The access to these pages is disabled by hardware. Even a turbo-R has the 'mirror' effect, but you can not say that this is the only thing you have to look at to determine the number of mapper pages. By the way, there is a trick to alter these pages: * switch to R800-ROM and these pages are accessible * make changes (e.g. replace KANJI with KUN, I use this method now and then) * and switch back to R800-DRAM H... Here comes a nice thing, not related to this subject, but I have noticed that access to the internal ram of the turbo-R is faster than access to external memory/ram. So it is faster to run KUN-Basic in place of the kanji-ram-place than from an rom-module in a cartridge slot. Another thing is : data that has to be accessed a lot should be in the internal ram of the turbo-R. Not only because of the slot-switching, but because of the access time too! Greetings from Erik Maas p.s. I don't know what kind of program is under development, but I hope the mapper MSX Mailinglist. To unsubscribe, send an email to [EMAIL PROTECTED] and put in the body (not subject) "unsubscribe msx [EMAIL PROTECTED]" (without the quotes :-) Problems? contact [EMAIL PROTECTED] (www.stack.nl/~wiebe/mailinglist/)
Re: Memory Mapper mirror effect?
Anyone knows if there are memory mappers with mirror effect (i.e., for example, a 128k mapper (8 pages), if I select page 16, I'll get page 8). I don't know any, but maybe there is... All mappers do this 'mirroring'... If they didn't then it would not be possible to detect the mappersize... (only legal mappersize-detection is done by using the mirror-effect). ~Grauw -- email me: [EMAIL PROTECTED] or ICQ: 10196372 visit the Datax homepage at http://datax.cjb.net/ MSX fair Bussum / MSX Marathon homepage: http://msxfair.cjb.net/ MSX Mailinglist. To unsubscribe, send an email to [EMAIL PROTECTED] and put in the body (not subject) "unsubscribe msx [EMAIL PROTECTED]" (without the quotes :-) Problems? contact [EMAIL PROTECTED] (www.stack.nl/~wiebe/mailinglist/)
Memory Mapper mirror effect?
Hi, folks. Anyone knows if there are memory mappers with mirror effect (i.e., for example, a 128k mapper (8 pages), if I select page 16, I'll get page 8). I don't know any, but maybe there is... Thanks, Adriano Camargo Rodrigues da Cunha ([EMAIL PROTECTED]) Engenharia de Computacao - UNICAMP http://www.adrpage.cjb.net MSX-TR:I have one.And you? * Suicide is like saying to God - You can't fire me ! I am quiting! * MSX Mailinglist. To unsubscribe, send an email to [EMAIL PROTECTED] and put in the body (not subject) "unsubscribe msx [EMAIL PROTECTED]" (without the quotes :-) Problems? contact [EMAIL PROTECTED] (www.stack.nl/~wiebe/mailinglist/)
Re: Memory Mapper mirror effect?
On Wed, 15 Sep 1999, Adriano Camargo Rodrigues da Cunha wrote: Anyone knows if there are memory mappers with mirror effect (i.e., for example, a 128k mapper (8 pages), if I select page 16, I'll get page 8). I don't know any, but maybe there is... Sure there is! I don't know how Turbo-R's Mapper works, but standard mappers have mirror effect. If you select block 16, you'll get block 0, and the same will happen if you select block 8. (blocks are numbered from 0 to 7). But the most interesting is to select the same block in different RAM pages. You can write a byte in one address, and in another address the same byte appears! Really cool! Greetings from Brazil! - Marco Antonio Simon Dal Pozhttp://www.lsi.usp.br/~mdalpoz [EMAIL PROTECTED] "Apple" (c) Copyright 1767, Sir Isaac Newton MSX Mailinglist. To unsubscribe, send an email to [EMAIL PROTECTED] and put in the body (not subject) "unsubscribe msx [EMAIL PROTECTED]" (without the quotes :-) Problems? contact [EMAIL PROTECTED] (www.stack.nl/~wiebe/mailinglist/)
