Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!noose.ecn.purdue.edu!stable.ecn.purdue.edu!yorkw From: yorkw@stable.ecn.purdue.edu (Willis F York) Newsgroups: comp.sys.amiga.hardware Subject: Re: Beginer Questions (How Does the amiga use MEMORY?) Message-ID: Date: 9 Jan 91 18:00:23 GMT References: <6812@crash.cts.com> Sender: news@noose.ecn.purdue.edu (USENET news) Organization: Purdue University Engineering Computer Network Lines: 82 lkoop@pnet01.cts.com (Lamonte Koop) writes: >Not necessarily. You will only run into having to have wait states if the >memory being utilized is slower than the speed at which the processor needs it >to come back. For instance, FAST RAM on the A2000 (68000) is usually rated at >120-100ns...this is perfectly fine for zero-wait state operation on that bus. >The processor is incapable of "asking for" the data any faster. Putting 80ns ^^^^^^^^^^^^ >memory here would be a waste of money, as the processor will not be able to Kinda a "specific" question but my ADRAM board came with M514256A-80R chips, the 80R means 80 ns (The R means ???) so the company i got the chips from sent "faster" chips than what was needed right?, or perhaps the ADRAM board needs faser chips because it'sa "Hack" replacing the A501. Must i use more 80ns chips to upgrade. (I'm attempting to save $$) What weirdness could happen it i used say 120ns chips might this cause problems. It's my birthday so i want to get my board up to 4 meg.. oops this is getting more Hardware-Tech, talk.. Sorry. C-ya . >access it any faster. [The processor/bus is running at a certain speed...it >will not speed up for faster memory]. Now, if you were to put 200ns parts on >a FAST RAM expansion board, you would have to put some wait states into that. >>Does the "ROM" get copied to "RAM" and get run (Bad word) from there? >>(I heard this and it "seems" silly) >I think you are confusing something done on accelerators here. On normal >systems, the ROM code is run straight out of the ROM itself...no "copying to >RAM" occurs. On many accelerators, (ones with an MMU in place), it is >possible to take an "image" of that ROM, copy it to a faster medium (32-bitr >bus area...the accelerator's memory area), then use the MMU to translate >address requests to where the ROM image originally was to it's new (hopefully >faster) location. THis is done to speed up the system ROM calls. However, >normally the ROM is simply accessed directly. >> >>What's so important about "Fastmemfirst" ? Does it prevent the >>using up of "CHIP" befor "Other" memory is full? How does it do it? >Memory on the Amiga is prioritized. Now, normally CHIP RAM is given a >priority on the system of -10. This is to insure it is not used by programs >requesting simply "I want a chunk of memory", and not saying "and it needs to >be CHIP". This helps prevent CHIP RAM from being used for things which do not >need to be there. Now, FastMemFirst is special. On Amigas with 512K of CHIP >RAM, the other 512K which make up the 1 meg std. complement is what is called >"SLOW-FAST" RAM. This is because, while the custom chips cannot use it, it is >still subject to the bus contention for CHIP RAM I mentioned earlier, as it is >in fact on that bus. [When you upgrade to the 1-meg Agnus, this "SLOW-FAST" >memory is what becomes the other 512K of CHIP RAM.] FastMemFirst is useful if >you have this "SLOW- >FAST" memory, and also have true FAST memory on the system. What it does is >place your "SLOW-FAST" memory at the same -10 priority as CHIP RAM. Since >most true FAST RAM will default to a priority of 0, it places your true FAST >RAM ahead of the CHIP and SLOW-FAST memory on the memory lists. This is so >programs which do not need to use CHIP RAM (and a program's actual CODE never >does for the most part) will be placed in you FAST RAM, and run somewhat >faster. SLOW-FAST and CHIP will only be used when either requested >specifically by a program, or when your FAST RAM is filled. > LaMonte Koop > Internet: lkoop@pnet01.cts.com ARPA: crash!pnet01!lkoop@nosc.mil > UUCP: {hplabs!hp-sdd ucsd nosc}!crash!pnet01!lkoop > A scientist is one who finds interest in the kinetic energy of Jell-O > moving at ridiculous velocities...an engineer is one who can find a > real-life application for such silliness. -- yorkw@ecn.purdue.edu Willis F York ---------------------------------------------- Macintosh... Proof that a Person can use a Computer all day and still not know ANYTHING about computers.