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I understand that registers are temporary storage compartments which (usually) hold 8 bits, or 1 byte, of information at a time. This information is sent from a register into the Central Processing Unit (CPU) where, with the help of a control unit and an ALU, the byte is decoded and sent back to occupy the space of another register. This data is finally transferred from the register to the storage and into primary memory, such as ROM or RAM, but I am unclear whether this is the case. Could someone please help elaborate if I have missed anything crucial in the process and whether the outcome should be as such? In my mind, that is how a processor would handle data as registers would be used to fill up the free space of primary memory; Input > Register > CPU > Register > Output / Store

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  • $\begingroup$ On many modern processors, registers hold 32, 64, 128 or 256 bits of information. 8 bits would have been the normal thing in the late 1970's or early 1980's. $\endgroup$ – gnasher729 Aug 15 '16 at 16:22
  • $\begingroup$ Memory -> Register -> ALU -> Register -> Memory is not unusual. But the data need not come from memory, it need not be stored in memory, it need not go through the ALU but might go directly to another register, or you might move Memory -> Register -> Memory. All possible. $\endgroup$ – gnasher729 Aug 15 '16 at 16:24
  • $\begingroup$ Input > InputRegister > CPU > OutputRegister. After that you have to request it from OutputRegister, the CPU wont "send it back" $\endgroup$ – Petar Mihalj Aug 15 '16 at 16:51
  • $\begingroup$ DMA skips the CPU entirely. Memory mapped I/O uses the CPU but may skip registers entirely. $\endgroup$ – Xodarap Aug 15 '16 at 16:53
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    $\begingroup$ The title of your question seems to be a poor fit to the content. Could you maybe edit? $\endgroup$ – adrianN Aug 16 '16 at 12:03

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