Is it possible that embedded system doesn't have flash memory? If we use flash memory in embedded system, then we don't need to use ROM, or both? My understanding is that flash memory is similar to ROM, that stores permanent data like boot up instructions?? Is that correct? Please advice. thanks...
Why and when flash memory is needed in embedded system?
Started by ●September 21, 2006
Reply by ●September 21, 20062006-09-21
John wrote:> Is it possible that embedded system doesn't have flash memory? If we > use flash memory in embedded system, then we don't need to use ROM, or > both? My understanding is that flash memory is similar to ROM, that > stores permanent data like boot up instructions?? Is that correct? > Please advice. thanks... >I think some form of non-volatile memory is needed in a system of any complexity. I can picture an ASIC or CPLD that does something useful yet has no non-volatile memory. Like a sound effect generator, one button switches sounds, the other button turns sound generation on. The non-volatile memory doesn't need to be flash. It can even be SRAM with battery backup. Flash memory is rom, it's just programmable in circuit by the circuit/system itself. -Dave -- David Ashley http://www.xdr.com/dash Embedded linux, device drivers, system architecture
Reply by ●September 21, 20062006-09-21
David Ashley wrote:> I think some form of non-volatile memory is needed in a system > of any complexity. I can picture an ASIC or CPLD that does > something useful yet has no non-volatile memory. Like a > sound effect generator, one button switches sounds, the other > button turns sound generation on. >If the embedded system doesn't have flash memory, how can it boot up?? I keep thinking flash memory or ROM is used for boot up process. is that true? please advice more....
Reply by ●September 21, 20062006-09-21
John wrote:> David Ashley wrote: > >>I think some form of non-volatile memory is needed in a system >>of any complexity. I can picture an ASIC or CPLD that does >>something useful yet has no non-volatile memory. Like a >>sound effect generator, one button switches sounds, the other >>button turns sound generation on. >> > > > If the embedded system doesn't have flash memory, how can it boot up?? > I keep thinking flash memory or ROM is used for boot up process. > > is that true? please advice more.... >Why flash? Why not a rom? Eprom. EEprom. Serial rom. CPLD. Compact flash. ACE. If you need more information than can be stored in the raw logic of the device(s), then you need some other form of non-volatile memory. Where's the mystery? An embedded system doesn't necessarily need a cpu. Or an OS. -Dave -- David Ashley http://www.xdr.com/dash Embedded linux, device drivers, system architecture
Reply by ●September 21, 20062006-09-21
"John" <javacc1@gmail.com> wrote in message news:1158825604.736539.96750@d34g2000cwd.googlegroups.com...> > David Ashley wrote: >> I think some form of non-volatile memory is needed in a system >> of any complexity. I can picture an ASIC or CPLD that does >> something useful yet has no non-volatile memory. Like a >> sound effect generator, one button switches sounds, the other >> button turns sound generation on. >> > > If the embedded system doesn't have flash memory, how can it boot up?? > I keep thinking flash memory or ROM is used for boot up process. > > is that true? please advice more....ROM is not necessarily Flash. Flash is just a convenient method of being able to reprogram ROM chips. In the old days ROM consisted of fuses that were blown so the data was permanently etched into the memory. Later on erasable ROMs became avaiable but you had to shine UV light on them to clear. Speaking to a very old hairy-eared engineered once he told be that the ROM he used many many years ago was windings of copper wire with ferrite beads on them to represent data. Apparently they always used women to wind the wires because they were more accurate than men. But I digress.... As long as there is some kind of memory available to the processor that is not lost when the power is removed (so it is non-volatile) then it will be able to boot. Flash is one type of possible memory (and the most common) but so is battery backed Static RAM or an old-school PROM or a number of other methods.
Reply by ●September 21, 20062006-09-21
Tom Lucas wrote:> >> I think some form of non-volatile memory is needed in a system > >> of any complexity. I can picture an ASIC or CPLD that does > > > > If the embedded system doesn't have flash memory, how can it boot up?? > > ROM is not necessarily Flash. Flash is just a convenient method of beingYou wasted far too much time on this answer. The correct response was "The answers to your homework can be found in the reading list provided by your professor".
Reply by ●September 21, 20062006-09-21
"larwe" <zwsdotcom@gmail.com> wrote in message news:1158836873.412510.51280@m73g2000cwd.googlegroups.com...> > Tom Lucas wrote: > >> >> I think some form of non-volatile memory is needed in a system >> >> of any complexity. I can picture an ASIC or CPLD that does >> > >> > If the embedded system doesn't have flash memory, how can it boot >> > up?? >> >> ROM is not necessarily Flash. Flash is just a convenient method of >> being > > You wasted far too much time on this answer. The correct response was > "The answers to your homework can be found in the reading list > provided > by your professor".It's not often someone asks a question I know the answer to :-) I don't think the students are back yet are they? The UK ones only put down their burger flippers on Sunday and are still too drunk to post on usenet.
Reply by ●September 21, 20062006-09-21
Tom Lucas wrote:> > "The answers to your homework can be found in the reading list > > provided by your professor". > > I don't think the students are back yet are they? The UK ones only put > down their burger flippers on Sunday and are still too drunk to post onUS students have been back at school for at least two weeks. (My wife is a seventh grade teacher, and I'm back at college myself... so I know these things).
Reply by ●September 21, 20062006-09-21
"larwe" <zwsdotcom@gmail.com> wrote in message news:1158844321.938326.21960@b28g2000cwb.googlegroups.com...> > Tom Lucas wrote: > >> > "The answers to your homework can be found in the reading list >> > provided by your professor". >> >> I don't think the students are back yet are they? The UK ones only >> put >> down their burger flippers on Sunday and are still too drunk to post >> on > > US students have been back at school for at least two weeks. (My wife > is a seventh grade teacher, and I'm back at college myself... so I > know > these things).My girlfriend is now in her second week as a newly qualified maths teacher. Unfortunately, she has little time to do anything else so all our conversations must be about what the little buggers have been up to this week. I guess this must be revenge for the time I spend disseminating the virtues of my GP2X to her ;-)
Reply by ●September 21, 20062006-09-21
