Perhaps this question may sound silly,and am sorry if there are similar questions answered already because i couldn't find one, as per guidelines. Mask ROM(MROM) are programmed while manufacturing,PROM can be programmed after manufacture and same follows to EPROM and EEPROM similarly how are ROM's are programmed. I assume ROM and MROM are two different things,latter one with program in it loaded while manufacturing. Also if i have wrong concept in my head please make it clear.

  • \$\begingroup\$ what is a normal ROM? \$\endgroup\$ – jsotola Mar 29 '18 at 19:23
  • \$\begingroup\$ as per edited question @jsotola \$\endgroup\$ – Samdare Mar 29 '18 at 19:28
  • \$\begingroup\$ ROM describes single behaviour of a memory but that can be manufactured by a variety of technologies (processes). (These names often spark enthusiastic and well-meaning but pernicketty discussions with no end because it's hard to put everyone's 'I know it when I see it' definitions into a single absolute term...) \$\endgroup\$ – TonyM Mar 29 '18 at 19:34
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    \$\begingroup\$ See electronics.stackexchange.com/questions/243712/…. \$\endgroup\$ – Transistor Mar 29 '18 at 19:36
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    \$\begingroup\$ @PeterBennett no they were not RAM cores in the rope ROM, just ransformer cores. the data was represented by the routing of the address wires through the data cores. en.wikipedia.org/wiki/Core_rope_memory \$\endgroup\$ – Jasen Mar 29 '18 at 22:07

I assume ROM and MROM are two different things

You assume incorrectly. "ROM" is just an umbrella term that can be used to refer to any type of memory that cannot be modified after the device has been manufactured. If not otherwise specified, it usually refers to mask ROM, but it can also refer to other technologies which behave the same way, like PROM/EPROM devices or flash memory with writes disabled.

  • \$\begingroup\$ I think you mean 'cannot be modified by software'. The end user of an embedded system, such as a vending machine, cannot modify the ROM or anything else in its CPU system. \$\endgroup\$ – TonyM Mar 29 '18 at 20:01
  • \$\begingroup\$ @TonyM I mean the end user of the part, not of the device it's used in. A microcontroller may have a boot ROM which is implemented as flash, but is made non-writable before delivery to the "user" of the µC. \$\endgroup\$ – duskwuff -inactive- Mar 29 '18 at 20:13
  • \$\begingroup\$ Would be good to clarify that in your answer. There's only one end user in anything: the user of the final product. Follows that I should downvote, I'm afraid, will remove once terminology clarified. \$\endgroup\$ – TonyM Mar 29 '18 at 20:24
  • \$\begingroup\$ I might say that "ROM" is any sort of memory that cannot be written to using a normal processor "write" cycle. \$\endgroup\$ – Peter Bennett Mar 29 '18 at 22:11
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    \$\begingroup\$ @PeterBennett That's probably too broad. NAND flash memory would be swept up by that definition, for instance.. \$\endgroup\$ – duskwuff -inactive- Mar 29 '18 at 22:14

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