kenc@vaxb.acs.unt.edu (01/08/91)
> hardware in general. It seems to me that I can just pull out my old > 68000, plop in a new one rated at 16MHz, and then run the 16MHz clock > line to the new 68000? For that matter, can I move up to a 68020 Chris, This is a no go, because of the way that the CPU and the MMU swap cycles. From what I understand, the system clock ALREADY runs at 16 Mhz, but it gives half to the 68000, and half to the MMU. (I may have the wrong chip...it may be the glue...) Anyway, since THAT chip, and all the support chips are not rated at anything like 16 Mhz, and all the timing is sensitive, you try to double the speed of the system clock, and you have an expensive paperweight. I think the speed up kits available use a caching technique, so that the new chip DOES run at 16 Mhz, for it's cache, and 8Mhz for anything else. That way, you do get the speed improvement, and the system timing doesn't change. Only problem, is that that usually requires a caching chip, and another daughterboard, making the cost more than $100. If I'm wrong here, please jump in, I'd LOVE to be able to speed up my ST for <$100....(grin)
kilian@seas.gwu.edu (Jens Kilian) (01/09/91)
In Article 1068 of comp.sys.atari.st.tech, kenc@vaxb.acs.unt.edu writes: > Chris, > This is a no go, because of the way that the CPU and the MMU swap cycles. > >From what I understand, the system clock ALREADY runs at 16 Mhz, but it gives > half to the 68000, and half to the MMU. (I may have the wrong chip...it may be > the glue...) > Anyway, since THAT chip, and all the support chips are not rated at anything > like 16 Mhz, and all the timing is sensitive, you try to double the speed of > the system clock, and you have an expensive paperweight. > I think the speed up kits available use a caching technique, so that the new > chip DOES run at 16 Mhz, for it's cache, and 8Mhz for anything else. That way, > you do get the speed improvement, and the system timing doesn't change. Only > problem, is that that usually requires a caching chip, and another > daughterboard, making the cost more than $100. > > If I'm wrong here, please jump in, I'd LOVE to be able to speed up my ST for > <$100....(grin) The cheapest speed-up board I've seen was a project by the German magazine "c't" (one of the fall issues, but I can't check it now). It should be around $100 or cheaper, IF you're prepared to put it together yourself. As far as I remember, it only speeds up accesses to the ROMs and internal CPU operations, in RAM it runs at the normal speed (you can't speed up RAM accesses because the Shifter needs to access video RAM at fixed intervals). It has no cache, so it isn't as effective as the commercial boards, but it's CHEAP. Jens Kilian -- Internet: kilian@seas.gwu.edu SnailMail: 4715 MacArthur Blvd. UUCP: ...uunet!seas.gwu.edu!kilian Washington, DC 20007 "Sie hawwe-mer so e bekannt Physionomie, ich mahn, ich misst Ihne kenne. Sinn-Se net, um Vergebung, der Herr Assesser Ranft ?"