Path: utzoo!attcan!uunet!lll-winken!decwrl!shlump.nac.dec.com!clo!coburn From: coburn@clo.enet.dec.com (John T. Coburn) Newsgroups: comp.sys.amiga.tech Subject: Re: 32 bit RAM Message-ID: <9053@shlump.nac.dec.com> Date: 9 Mar 90 15:32:48 GMT Sender: newsdaemon@shlump.nac.dec.com Organization: DEC - EIS Cleveland, Ohio Lines: 48 In article <1778@crash.cts.com>, hawk@pnet01.cts.com (John Anderson) writes... : : Thank you to all those that responded to my inquiries and questions about :32 bit RAM and 16 bit etc. So basically what I understand to be true is that :32 bit is 4 bytes wide (which I already knew) so it can hold *4* instructions :instead of just *2* like 16 bit RAM? (that is the part I didn't know about). :I thought each instruction was 32 bits in length and needed to be stored at :two 16 bit addresses so when it was used in 32 bit RAM it took up 32 bits for :that same one instruction. Am I right so far in saying the first is right and :the second (what I used to think) is wrong? : Not exactly (although we may just have semantics problems here). The difference between 32 bit RAM and 16 bit RAM is that the bus used to access the memory is twice as wide (32 vs 16 bits). This allows twice as much data to be moved from memory to processor in the same amount of time (ie. memory access). This has no effect on the 680x0 instruction size or how much memory (number of bits) is used for a particular program. The reason that 32bit RAM isn't used on the 68000 is that it only supports the 16 bit databus and the 68030 supports the 32bit databus (ie. has more pins to access more databits in one access). Hope this helps a little bit. : : Also, I got that each instruction is one byte not 4 bytes long but since :the data length is a maximum of 32 bits then this leaves and option to have a :number stored in 32 bits (taking up 4 bytes) if it is needed to be that big(or :that accurate). Is this also true? If this is also true then I appreciate Even with 16bit RAM you could have 32 bit numbers stored and used by the processor - it would take 2 memory accesses to retrieve the entire number to the processor. :all the help I got from those that replied and helped me. If only some is tru :then I still thank you and could you shed some light on me on the stuff I :still dont understand? Even if I'm right could someone in the know let me :know that I got it? Thanks again... -------------------------------------------------------------------------------- John Coburn !Email: Digital Equipment Corporation ! coburn%clovax.enet.dec@decwrl.dec.com Enterprise Integration Services ! Cleveland, Ohio ! ...!decwrl!clovax.enet.dec.com!coburn ================================================================================