0

The address bus is typically a double octet wide (i.e. 16-bit), due to practical and economical considerations. This implies a direct address space of only 64 kB on most 8-bit processors

This quote is from Wikipedia of 8 bit computing. It shows us that we can use a 16 bit memory with an 8 bit processor, and this sounds promising to the question of how to access more than 15 addresses from our ROM, but will this affect the usage of our processor itself? The only thing I need to keep 16 bit will be the address register, isn't it?im not using a processor but im interested in building one , this link - How can 8-bit processor support more than 256 bytes of RAM? , doesn't solve my problem

SHikha Mittal
  • 179
  • 7
  • 2
    You're going to have to provide a lot more details in order to have an answerable question. If you are using an existing processor, *identify it specifically*. If you are *designing* a processor (hopefully in an FPGA!) then you probably want to study some 8-bit designs with 16 bit address space first. All of your address calculation logic will need to be able to generate a 16 bit output, and you'll need a way to do at least a register-relative if not an absolute load/store and branch... – Chris Stratton Sep 28 '20 at 15:13
  • 1
    I think this post will help answer your question https://electronics.stackexchange.com/questions/57950/how-can-8-bit-processor-support-more-than-256-bytes-of-ram – Pangus Sep 28 '20 at 15:16
  • 1
    You CAN use a 16 bit memory on an 8 bit CPU ... trivially, by ignoring half the data bus and half the memory, at least. But that's not even vaguely related to what this quotation is saying. Quotation is about address bus width which is completely irrelevant to data width. –  Sep 28 '20 at 15:29
  • 2
    Does this answer your question? [How can 8-bit processor support more than 256 bytes of RAM?](https://electronics.stackexchange.com/questions/57950/how-can-8-bit-processor-support-more-than-256-bytes-of-ram) –  Sep 28 '20 at 15:31
  • 2
    Please clarify if you mean using a memory with 16-bit data or 16-bit address bus. Because both are possible as long as the memory is still byte-addressable. Or if you are willing to waste half of it. The memory size is not a problem, in theory you can connect as much memory as you want to a 8-bit processor, be it 1 megabyte or 4 gigabytes. – Justme Sep 28 '20 at 15:33
  • 16-bit memory is the width of the data, not the width of the address bus – jsotola Sep 28 '20 at 15:56
  • @jsotola But the Wikipedia quote describes 16-bit addressing of 8-bit memory. Hence the need to clarify which the OP means. – Guy Inchbald Sep 28 '20 at 16:33
  • 1
    If you have tried making a processor, you should have realized that the processor has lots of parts inside it and nothing forces them to all be the same size. This part can be 16 bits even if that part is 8 bits. Of course, that means if you want to transfer data from that part to this part, you can only transfer half at a time. – user253751 Sep 28 '20 at 17:05

0 Answers0