Post by thread:ROM vs OTP

I just rec'd the new Microchip line card. Inside they have a new category of parts classified as "R" such as 12CR509. The only difference they show is that the "R" version is classified as ROM where the others are listed as OTP/Flash. Many of course are not flash. OTP is ROM, so what are they getting at here? Or is this just another way to classify window parts? Thanks Jack Shidemantle Automation & Development Engineer YSI, Inc. USA

OTP parts are really EPROM devices without a window to erase them. ROM parts are actually Masked ROM parts. You have to send your code to Microchip, and they hard code it into the part. The result of this is that the parts are much cheaper than using OTP parts, if you have enough volume to justify the initial setup costs. Hope this helps. Regards, Jim {Quote hidden}>I just rec'd the new Microchip line card. Inside they have a new >category of parts classified as "R" such as 12CR509. The only >difference they show is that the "R" version is classified as ROM >where the others are listed as OTP/Flash. Many of course are not >flash. OTP is ROM, so what are they getting at here? Or is this just >another way to classify window parts? > >Thanks >Jack Shidemantle >Automation & Development Engineer >YSI, Inc. USA >

At 13:32 02/17/99 -0500, Jack Shidemantle wrote: >I just rec'd the new Microchip line card. Inside they have a new >category of parts classified as "R" such as 12CR509. The only >difference they show is that the "R" version is classified as ROM >where the others are listed as OTP/Flash. Many of course are not >flash. OTP is ROM, so what are they getting at here? i don't know how they see it (like in marketing != technical), but ReadOnlyMemory is not OneTimeProgrammable memory. OTP is an EPROM variety, ROM is usually mask ROM. ge

OTP is PROM, which is an EPROM with no window. The pattern 'blown' into a ROM is done with metalisation layers during the final stages of production, which means that you have to commit to a lot of parts. Rgds... ...Andy At 13:32 17/02/99 -0500, you wrote: {Quote hidden}>I just rec'd the new Microchip line card. Inside they have a new >category of parts classified as "R" such as 12CR509. The only >difference they show is that the "R" version is classified as ROM >where the others are listed as OTP/Flash. Many of course are not >flash. OTP is ROM, so what are they getting at here? Or is this just >another way to classify window parts? > >Thanks >Jack Shidemantle >Automation & Development Engineer >YSI, Inc. USA >

At 08:25 PM 2/17/99 +0000, Andy Stephenson wrote: >OTP is PROM, which is an EPROM with no window. > >The pattern 'blown' into a ROM is done with metalisation layers during the >final stages of production, which means that you have to commit to a lot of >parts. They're cheap, as long as you're <SURE> your code is not going to change. We went OTP for a while and then mask, and still ended up with a bug in one product. It was discovered about 8 weeks after we submitted our code for a 12 week process, and had committed to 5000 chips. Fortunately, it wasn't a huge bug.

It's a tough break when that happens. It's exactly why Microchip have successfull with the OTP's. They can work out cheaper (more cost effective as Microchip would say) than going to ROM when things like that happen. If you talk to your Microchip rep, you will probably find that they would rather screw down the price on your OTP's in volume rether than going mask ROM. Motorola on the other hand, would rather go ROM than OTP.... Horses for courses. Temic on the 8051 types expect screw up's - they give you one free turn - and you use it! Rgds... ...Andy At 16:08 17/02/99 -0500, you wrote: {Quote hidden}>At 08:25 PM 2/17/99 +0000, Andy Stephenson wrote: >>OTP is PROM, which is an EPROM with no window. >> >>The pattern 'blown' into a ROM is done with metalisation layers during the >>final stages of production, which means that you have to commit to a lot of >>parts. > >They're cheap, as long as you're <SURE> your code is not going to change. >We went OTP for a while and then mask, and still ended up with a bug in one >product. It was discovered about 8 weeks after we submitted our code for a >12 week process, and had committed to 5000 chips. > >Fortunately, it wasn't a huge bug. >

On Wed, 17 Feb 1999, Jack Shidemantle wrote: > I just rec'd the new Microchip line card. Inside they have a new > category of parts classified as "R" such as 12CR509. The only > difference they show is that the "R" version is classified as ROM > where the others are listed as OTP/Flash. Many of course are not > flash. OTP is ROM, so what are they getting at here? Or is this just > another way to classify window parts? > OTP and EPROM chips are essentially the same, except the OTP parts do not have a window. Kinda hard to erase them:) ----------------------------------------------------------------------- The Pinto Page: http://www.eng.usf.edu/~shidel Join the Ford Turbo Mailing List! http://www.FindMail.com/list/turbo/ Scott -71 Pinto, stock 2.3 turbo, 13.67@98, radials 8.1@85 1/8th mile on slicks -85 Merkur 13.764@98 on radials&3300lbs! Under $300 in mods! ------------------------------------------------------------------------

On Wed, 17 Feb 1999, Mr and Mrs James Paul wrote: > OTP parts are really EPROM devices without a window to erase > them. ROM parts are actually Masked ROM parts. You have to > send your code to Microchip, and they hard code it into the > part. The result of this is that the parts are much cheaper > than using OTP parts, if you have enough volume to justify the > initial setup costs. Hope this helps. > What? I thought that you could program OTPs yourself, but you just couldnt erase it once you did. What gives? ----------------------------------------------------------------------- The Pinto Page: http://www.eng.usf.edu/~shidel Join the Ford Turbo Mailing List! http://www.FindMail.com/list/turbo/ Scott -71 Pinto, stock 2.3 turbo, 13.67@98, radials 8.1@85 1/8th mile on slicks -85 Merkur 13.764@98 on radials&3300lbs! Under $300 in mods! ------------------------------------------------------------------------

What do you mean what gives. What you say is true. I didn't say anything contrary to that, did I? If I did, I didn't mean to. Regards, Jim {Quote hidden}>On Wed, 17 Feb 1999, Mr and Mrs James Paul wrote: > >> OTP parts are really EPROM devices without a window to erase >> them. ROM parts are actually Masked ROM parts. You have to >> send your code to Microchip, and they hard code it into the >> part. The result of this is that the parts are much cheaper >> than using OTP parts, if you have enough volume to justify the >> initial setup costs. Hope this helps. >> > >What? >I thought that you could program OTPs yourself, but you just couldnt erase >it once you did. What gives? > >----------------------------------------------------------------------- > The Pinto Page: http://www.eng.usf.edu/~shidel > Join the Ford Turbo Mailing List! > http://www.FindMail.com/list/turbo/ >Scott >-71 Pinto, stock 2.3 turbo, 13.67@98, radials > 8.1@85 1/8th mile on slicks >-85 Merkur 13.764@98 on radials&3300lbs! Under $300 in mods! >------------------------------------------------------------------------ >

At 05:49 PM 2/17/99 -0500, Scott Shidel... wrote: >On Wed, 17 Feb 1999, Mr and Mrs James Paul wrote: > >> OTP parts are really EPROM devices without a window to erase >> them. ROM parts are actually Masked ROM parts. You have to >> send your code to Microchip, and they hard code it into the >> part. The result of this is that the parts are much cheaper >> than using OTP parts, if you have enough volume to justify the >> initial setup costs. Hope this helps. >> > >What? >I thought that you could program OTPs yourself, but you just couldnt erase >it once you did. What gives? Das what he said.. OTPs are windowless EPROMS, and they are more expensive than ROM parts.

O, I misunderstood. I thought you were saying that OTPs HAD to be hardcoded by Microchip, and that self programming wasnt an option. On Wed, 17 Feb 1999, Mr and Mrs James Paul wrote: {Quote hidden}> What do you mean what gives. What you say is true. I didn't > say anything contrary to that, did I? If I did, I didn't mean > to. > > >On Wed, 17 Feb 1999, Mr and Mrs James Paul wrote: > > > >> OTP parts are really EPROM devices without a window to erase > >> them. ROM parts are actually Masked ROM parts. You have to > >> send your code to Microchip, and they hard code it into the > >> part. The result of this is that the parts are much cheaper > >> than using OTP parts, if you have enough volume to justify the > >> initial setup costs. Hope this helps. > >> > > > >What? > >I thought that you could program OTPs yourself, but you just couldnt erase > > >it once you did. What gives? > > > >----------------------------------------------------------------------- > > The Pinto Page: http://www.eng.usf.edu/~shidel > > Join the Ford Turbo Mailing List! > > http://www.FindMail.com/list/turbo/ > >Scott > >-71 Pinto, stock 2.3 turbo, 13.67@98, radials > > 8.1@85 1/8th mile on slicks > >-85 Merkur 13.764@98 on radials&3300lbs! Under $300 in mods! > >------------------------------------------------------------------------ > > > ----------------------------------------------------------------------- The Pinto Page: http://www.eng.usf.edu/~shidel Join the Ford Turbo Mailing List! http://www.FindMail.com/list/turbo/ Scott -71 Pinto, stock 2.3 turbo, 13.67@98, radials 8.1@85 1/8th mile on slicks -85 Merkur 13.764@98 on radials&3300lbs! Under $300 in mods! ------------------------------------------------------------------------

Don't feel bad. I thought that was what he meant too. {Quote hidden}> -----Original Message----- > From: pic microcontroller discussion list > [spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU]On Behalf Of Scott Shidel... > Sent: Wednesday, February 17, 1999 6:07 PM > To: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU > Subject: Re: ROM vs OTP > > > O, I misunderstood. I thought you were saying that OTPs HAD to be > hardcoded by Microchip, and that self programming wasnt an option. > > On Wed, 17 Feb 1999, Mr and Mrs James Paul wrote: > > > What do you mean what gives. What you say is true. I didn't > > say anything contrary to that, did I? If I did, I didn't mean > > to. > > > > >On Wed, 17 Feb 1999, Mr and Mrs James Paul wrote: > > > > > >> OTP parts are really EPROM devices without a window to erase > > >> them. ROM parts are actually Masked ROM parts. You have to > > >> send your code to Microchip, and they hard code it into the > > >> part. The result of this is that the parts are much cheaper > > >> than using OTP parts, if you have enough volume to justify the > > >> initial setup costs. Hope this helps. > > >> > > > > > >What? > > >I thought that you could program OTPs yourself, but you just > couldnt erase > > > > >it once you did. What gives? > > > > > >----------------------------------------------------------------------- > > > The Pinto Page: http://www.eng.usf.edu/~shidel > > > Join the Ford Turbo Mailing List! > > > http://www.FindMail.com/list/turbo/ > > >Scott > > >-71 Pinto, stock 2.3 turbo, 13.67@98, radials > > > 8.1@85 1/8th mile on slicks > > >-85 Merkur 13.764@98 on radials&3300lbs! Under $300 in mods! > > > >------------------------------------------------------------------------ > > > > > > > ----------------------------------------------------------------------- > The Pinto Page: http://www.eng.usf.edu/~shidel > Join the Ford Turbo Mailing List! > http://www.FindMail.com/list/turbo/ > Scott > -71 Pinto, stock 2.3 turbo, 13.67@98, radials > 8.1@85 1/8th mile on slicks > -85 Merkur 13.764@98 on radials&3300lbs! Under $300 in mods! > ------------------------------------------------------------------------ >

> > OTP is PROM, which is an EPROM with no window. Actually these are not equivalent. A PROM cell has no mechanism for reversing state once the cell has been blown. A EPROM cell can be regenerated by exposure to UV. Even though in an OTP the EPROM is covered, nevertheless they are EPROM cells, which are different that PROM ones.... {Quote hidden}> > The pattern 'blown' into a ROM is done with metalisation layers during the > final stages of production, which means that you have to commit to a lot of > parts. > > Rgds... > > ...Andy > > At 13:32 17/02/99 -0500, you wrote: > >I just rec'd the new Microchip line card. Inside they have a new > >category of parts classified as "R" such as 12CR509. The only > >difference they show is that the "R" version is classified as ROM > >where the others are listed as OTP/Flash. Many of course are not > >flash. OTP is ROM, so what are they getting at here? Or is this just > >another way to classify window parts? > > > >Thanks > >Jack Shidemantle > >Automation & Development Engineer > >YSI, Inc. USA > > >