spencer@eris.UUCP (02/15/87)
>Randy, > > I doubt that your friend created 2 meg of chip memory, as that >requires an address line that is not in the Agnus chip that you would >need. I wish that there was a way to do this but not until the next >generation of chips appears.. I wish I was wrong but don't thin' so!! > >-Jim Becker >Terrapin Software The reason that I keep hashing on this is because of an article in Amazing Computing, and I quote (BTW, my dollar sign key don't work, I use "#"): [talking about adding internal memory] ...The reason this works is that Amiga most generously did not fully decode the lower 2 megabyte RAM space that the internal 256K and 256K expansion RAM fit into. They DID decode 1 megabyte, but they only used half of the available memory select lines. This makes it fairly easy to add the other 512K, because we don't even need to add any decoding IC's, just some jumpers. [...] What you end up with is your normal 512K of Chip RAM, mapped from #000000 to #07FFFF, and another 512K mapped from #080000 to #0FFFFF. This 1 megabyte 'shadows' over the next 1 megabyte, (from #100000 to #1FFFFF) because the next highest address bit (A20) is not used for decoding. This 1 megabyte was "reserved" by Commodore for internal memory expansion, and you could theoretically add another megabyte of RAM chips (along with a few more decoder and glue chips to decode this address space), giving you 2 megabytes of RAM. I say theoretically, because you will run out of power long before you have reached 2 megabytes. One megabyte, however, does not tax the Amiga's power supply, and leaves you with enough left over for a few goodies like A-time and Digi-View. [...] One final note is in order. If you try to use this memory with Workbench 1.2, you will find that Workbench 1.2 tries to auto- configure the extra memory as Chip RAM. This is probably due to the fact that the new "Fat Agnus" graphics chip will be able to address 2 megabytes, rather than the 512K that the current Agnus chip supports. What I get out of that is "put memory in this address space and the Amiga will autoconfigure it as chip memory." and "if you want to add 2 meg in this space you will run out of power." So, my friend is putting an extra power supply in and putting the memory in this address space and so by my understanding I read this to mean, if he doesn't take special precautions he will end up with chip ram that the graphics coprocessors can't look at. So he has to run a special program and/ or do something special in hardware. My last message said, "If you have 2 meg of chip memory (like this) and you had the new graphics chips, and you built a daughter board for them all, couldn't the new graphics chip work?" I just want to know if it is a not possible or if we all can ever expect to see Amazing Computing's "How to Upgrade your 512K Chip Ram Amiga" article. Instead I keep getting back mail that says "you can't have 2 meg of chip ram when you are bringing address lines from the fast ram expansion port." Well, I know that, but I gather from this article that that _ain't_ what we are talking about. If I didn't make myself clear this time I give up for fear that I am just being thick headed. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Randy Spencer P.O. Box 4542 Berkeley CA 94704 (415)284-4740 C#(415)283-5469 I N F I N I T Y spencer%eris@berkeley.edu Now working for |||||||||||::::... . . spencer@USCVAXQ.bitnet But in no way |||||||||||||||::::.. .. . ....ucbvax!eris!spencer Officially representing ||||||||||||:::::... .. s o f t w a r e -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
grr@cbmvax.UUCP (02/17/87)
In article <2539@jade.BERKELEY.EDU> spencer@eris.BERKELEY.EDU () writes: > >My last message said, "If you have 2 meg of chip memory (like this) and you >had the new graphics chips, and you built a daughter board for them all, >couldn't the new graphics chip work?" I just want to know if it is a not >possible or if we all can ever expect to see Amazing Computing's "How to >Upgrade your 512K Chip Ram Amiga" article. > >Instead I keep getting back mail that says "you can't have 2 meg of chip >ram when you are bringing address lines from the fast ram expansion port." >Well, I know that, but I gather from this article that that _ain't_ what >we are talking about. > >Randy Spencer P.O. Box 4542 Berkeley CA 94704 (415)284-4740 C#(415)283-5469 I don't think anybody it is really impossible for a serious hacker who is willing and able to rip up his hardware to make something work with future hi-res chips. However, it is not likely to be a 3 minute drop-in fix. The real issues are how much you would need to change to use the new chips, and how difficult it would be for your average man-on-the-street amiga owner to make the adaptation and debug it. If I screw up an Amiga it's no big deal, since I have the knowledge and tools to fix it. Not everbody feels this way... -- George Robbins - now working for, uucp: {ihnp4|seismo|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@seismo.css.GOV Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)