Chip Ram

[JuvUK]

ok so the a1200 has 2mb of chip ram and there is no way of adding more to it! well i have read on here the many very clever people that are making all sorts of prototype pcbs and projects i couldnt even begin to understand, so my question is, with all the talent we have here is there no one that can make some kind of chip ram expansion?
all the best Juv.U.K

[zipper]

Because you should first rewrite the OS to use more Chip.

[JuvUK]

hmmm ok i guess that scuppers that! lol

[Doobrey]

zipper wrote:
Because you should first rewrite the OS to use more Chip.

That's the easy bit. It's not even a rewrite, just change the end address of the loop which detects the amount of chipmem...that is assuming a single block of chipmem..but then you run into other problems cos the A1200's memory map is already defined, and there isn't enough space without rearranging it, which means recompiling some device drivers to use new addresses and potential problems with old software that bangs the hardware expecting things like the CIAs to be at the old addresses.


The hard part is the 'expansion board', which will basically be a new A1200 motherboard, with redesigned custom chips that can access more than 2Mb.

[Narayan]

AFAIK or AFAIR you can always add more chip ram via the expansion if only expansions were holdingthe chip ram, and not the fast ram. However, the fast ram is far more wanted and is a favour to do to amiga and it's users to leave the chip ram only as a built in ram or up to 2 Mb to keep it all clean and tidy, and produce fast ram as the rest, so everytime you go buying, you plainly take fast. Nothing more nothing less.

[JuvUK]

i have 128mb of fast ram, thats not my problem not having enough chip ram is my problem having 4 mb would be cool

[Piru]

@Narayan

AFAIK or AFAIR you can always add more chip ram via the expansion if only expansions were holdingthe chip ram, and not the fast ram. However, the fast ram is far more wanted and is a favour to do to amiga and it's users to leave the chip ram only as a built in ram or up to 2 Mb to keep it all clean and tidy, and produce fast ram as the rest, so everytime you go buying, you plainly take fast. Nothing more nothing less.

Not true.

You can not have more than 2MB chip memory. The maximum depends on the chipset not, not the OS. The OS could easily be hacked to see even 8MB (which you can see with UAE).

Even when the CPU would be able to address more than 2MB, the custom chipsets cannot. UAE >2MB hack is possible since they have full control of the chipset emulation, and the emulated chipset can easily be modified to support larger memory map.

@JuvUK

having 4 mb would be cool

Won't ever be possible with real Amiga.

[KThunder]

using normal osroms and os files uae allows up to 8megs chip ram. thats were the os limit hits. its hardware right now that limits us to 2megs. if i remember correctly it is the chipset that limits it. so there isnt a hack to allow it. you would have to redesign the ecs or aga chips. the 4000 has a jumper on the mobo that would have allowed 4 i think (it does not work, so dont get your hopes up) commodore didnt put that into the aga chipset.
even if the aaa chipset had come out it probably wouldnt have been included since commodore built rtg capabilities into the os so they were probably thinking of moving away from the custom chipset

[Zac67]

A simple reconstruction of Agnus/Alice would do: just add the missing address lines to the chip and enlarge the address registers - that's it!  :lol:  *scnr*

[KThunder]

ok when will you have it ready?  :-D

[Zac67]

Probably before AOS4.  ;-)