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Old May 7th, 2004, 07:12 AM   #1
abuelfun
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Program Memory

HELLOW
IAM CONFUSED PROGRAM MEMORY (INTERNAL PROGRAM MEMORY,MEMORY SUBMODULE )
1. INTERNAL PROGRAM MEMOY ( RAM ) IN WHICH THE PROGRAM STORED & CAN BE LOST IF POWER FAILURE OCCURS & NO BACK UP BATTERY SUPPLY.MY QUESTION THAT IF I DO NOT WANT TO LOSE MY PROGRAM SHAL I USE EPROM OR EEPROM, WHAT IS THE DIFFRENCE BETWEEN THEM , WHEN WE USE THEM & IF WE USE MEMORY SUBMODULE (EPRM OR EEPROM ) CAN WE IGNORE THE BACK UP BATTERY.
2.WHAT IS THE DIFFRENCE BETWEEN RAM & ROM
BEST REGARDS
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Old May 7th, 2004, 07:29 AM   #2
ArikBY
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Hi

The difference between EPROM to EEPROM is EPROM is for one time, after you burn it you canot burn it again.
EEPROM orE^2PROM is multi burns, so you can burn it many time you want.
If you have EPROM or EEPROM you dont need backup battery.
RAM is dynamic memory you can read and write data as long as you have power.
ROM is like EPROM you write it once and thats it.It contain the essential data for proper operation of the device.
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Old May 8th, 2004, 05:17 AM   #3
abuelfun
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program memory

hellow
barak
thank you for your reply , what do you mean by burn , do you mean losing information on eprom by burn also you said that eprom can be burned once a time only & eeprom for multy burn if we compare this by a recorder casset .
1.eprom /as a recorder casset where we can record for once a time & if we lose information can not be used again ( as disposable injection that you can throw out ).
2.EEPROM /as a recorder casset you can erace information & record a gain

DO YOU AGREE WITH ME FOR ITEM (1) & (2).

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Old May 8th, 2004, 07:53 AM   #4
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Hi

When I say burn I mean the process of writing on the memory device.
When you save file on CD you BURN it.
When You save on EPROM you brun it.
When you save on type recorder you record it.
Regarding your statements.
"1.eprom /as a recorder casset where we can record for once a time & if we lose information can not be used again ( as disposable injection that you can throw out )."
WE CAN READ THE INFO AGAIN AND AGAIN BUT WE CAN NOT WRITE AGAIN.
N02 is true in basis.
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Old May 8th, 2004, 07:54 AM   #5
jvdcande
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Arik,

I think you have been mistaken, what you say about EPROM is not true for EPROM, but it complies to PROM.

This is the list of possible memory systems:
  • RAM - Random Access Memory
    This type of memory is randomly accessible, meaning that you can alter any memorylocation whitout any restriction. It uses 5V al over, but memory content is lost when the power goes down (volatile memory).
  • ROM - Read Only Memory
    As the name says, this memory is only to be read. The contents are fixed at the production stage. Only feasable for large quantities.
  • PROM - Programmable Read Only Memory
    This is a blank memory that can be programmed only once. The programming voltage (typical 21V) is (much) higher than the normal voltage used to read the memory (5V).
  • EPROM - Erasable Programmable Read Only Memory
    This is essentially the same memory as a PROM, but it can be erased by putting the memory under UV-light during about half an hour. This type of memory is easily recognised by the little round window on top of the IC.
  • EEPROM - Electrically Erasable Programmable Read Only Memory
    This type of memory can be programmed over and over again. To erase the device you don't need UV light, but it can all be done by a simple 5V source. The programming can be done also with 5V. Because only one votage is needed, this type of memory is programmable in the CPU with some PLC's, e.g. Simatic S5.
  • NVRAM - Non-Volatile Random Access Memory
    This memory is comparable to RAM memory, but is non-volatile: if power goes down, the memory contents are not lost. In contradiction to EPROM and EEPROM, which have to be erased as a whole and than re-programmed, in NVRAM you can alter every single memory location by itself.

Remark 1: I'm talking about standard memory here, hence the 5V used as standard voltage. Nowadays there are 3.3V memories around, but these are more common in the PC market.
Remark 2: This list is not complete. The memory systems mentioned here have however been around for some time and are the base for most newer systems you can find nowadays. They are also the most commonly used ones, or they have been mentioned to show the roots of some of the others.
Remark 3: This list is more or less given in historical order. Indeed ROM came before PROM, which came before EPROM and so on.

Kind regards,
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Old May 8th, 2004, 08:42 AM   #6
ArikBY
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You right
In the industry we considering to the EPROM as one time like the PROM.
The process of erasing is not economic.
WE use EPROMs for places where EEprom can erase by electric shock.
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