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Hello All I hope you are fine , Please i have 2 Questions

  1. if the ISA is 16 bits and Ram is 8 bit only for one address what will happen?
  2. If My ram is 16 bits and ISA 16 bits the featch will get 16 bits and proccess 16 bits int the proccessor?

Thank you

Karim Fouad
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  • It is unclear what you mean by saying that RAM is 8-bit. You could mean that the data bus is only 8-bits wide, or that the RAM is byte addressable. – Erik Eidt Aug 30 '22 at 21:27
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    for (1.) the processor will have to fetch 2 bytes to make a whole instruction, right? Some designs fetch the 2 bytes sequentially/serially, while other designs fetch the 2 bytes concurrently, and for the latter the data bus would be at least 16 bits wide. – Erik Eidt Aug 30 '22 at 21:27
  • Being a 16-bit ISA doesn't imply that instructions are all 2 bytes wide. For example, 8086 has variable length instructions, some of them only one byte, some of them 6 or more bytes. (And 8088 is the same CPU but with an 8-bit bus interface, fetching two bytes separately instead of a 16-bit word in 8086.) – Peter Cordes Aug 30 '22 at 21:44
  • @ErikEidt "RAM is 8 bit only for one address". I think this means that each address holds one byte. In other words "we are on a byte-addressible system." – Raymond Chen Sep 13 '22 at 23:13
  • @RaymondChen, thanks, I must have miss read that. – Erik Eidt Sep 14 '22 at 00:04

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