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hi list i am going to put one question . when we program a eprom,if size of eprom is grater than code ,what happen to blank space.somebody told me that if space will be blank your system will hang. I programed chip but never happened like this. can anybody clear this doubt ? regards maheh

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Given that memories can only store values (and do not have an uninitialized state), any non-programmed memory location will undoubtedly contain some value (normally, for FLASH or EEPROM, this will be the erased-state value for the particular memory, usually $FF). So, now your question can be asnwered as if it were: What will be the effect on my program if there is extra unused code/data (which happens to be all $FF values) around the useful code/data? None! ----- Original Message ----- From: Mahesh Chandra <> To: <> Sent: Wednesday, May 01, 2002 11:14 AM Subject: [m68HC11] (no subject) > when we program a eprom,if size of eprom is grater than code ,what > happen to blank space.somebody told me that if space will be blank your > system will hang. I programed chip but never happened like this. can > anybody clear this doubt ? > maheh

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See below -- --- Avoid computer viruses, Practice safe hex --- -- Specializing in small, cost effective embedded control systems -- Robert L. (Bob) Smith Smith Machine Works, Inc. 9900 Lumlay Road Richmond, VA 23236 804/745-1065 ----- Original Message ----- From: "Mahesh Chandra" <> To: <> Sent: Wednesday, May 01, 2002 4:14 AM Subject: [m68HC11] (no subject) > > hi list > i am going to put one question . > when we program a eprom,if size of eprom is grater than code ,what > happen to blank space. The EPROM must be erased before you can program it. Windowed parts must be erased by a UV light source, OTP parts come in the erased state. Therefore every memory location contains binary ones ($FF). When you program, the locations specified in your program (S19) file will be changed to the specified program data in the S records. Locations that are not specified in your program file will not be changed, therefore all unprogrammed locations will remain in the erased state and contain $FF. >somebody told me that if space will be blank your system will hang. That statement does not make any real sense. I assume that your program is correct and does not try to execute in the erased ($FF) area. But, of course, if your program attempts to jump into the erased area it will surely fail eventually. > I programed chip but never happened like this. can > anybody clear this doubt ? If your program does not exactly fit the available EPROM space, then the unused area will be left in the erased ($FF) state. If your program is correct, it should never access the unused EPROM area and, therefore, that area will not affect the operation of the program. > regards > maheh > To unsubscribe from this group, send an email to:

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There is no problem with not filling the whole eprom as long as you do program the reset and interrupt vectors, otherwize it may hang as it does not know were to start or if a interrupt does happen it will also hang. My mc68hc711 has eprom from d000 to ffff the interupt and reset vectors are at ffd6 to ffff the program code is from d000 to f51b. so f51c to ffd5 are not used. I could use two prog commands but to make my life simpler I just type "prog d000 ffff". At 01:44 PM 5/1/2002 +0530, you wrote: >hi list > i am going to put one question . > when we program a eprom,if size of eprom is grater than code ,what >happen to blank space.somebody told me that if space will be blank your >system will hang. I programed chip but never happened like this. can >anybody clear this doubt ? >regards >maheh > > >To unsubscribe from this group, send an email to:

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