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Transfer Word Select: Difference between revisions
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The '''Transfer Word Select''' is the bottom 3 bits of DMAPx. | The '''Transfer Word Select''' is the bottom 3 bits of DMAPx. | ||
The block of memory transferred by a [[DMA]] is broken into some number of '''transfer units'''. A transfer unit may be one, two, or four bytes in size. | The block of memory transferred by a [[DMA]] is broken into some number of '''transfer units'''. A transfer unit may be one, two, or four bytes in size. Here is how the transfer word select determines how big transfer units are: | ||
When these three bits are 000, transfer units are one byte in size. | |||
When these three bits are 001, 010, or 110, transfer units are two bytes in size. | |||
Otherwise, transfer units are four bytes in size. | |||
[[Category:ASM]] | [[Category:ASM]] | ||
Latest revision as of 23:25, 26 July 2023
The Transfer Word Select is the bottom 3 bits of DMAPx.
The block of memory transferred by a DMA is broken into some number of transfer units. A transfer unit may be one, two, or four bytes in size. Here is how the transfer word select determines how big transfer units are:
When these three bits are 000, transfer units are one byte in size. When these three bits are 001, 010, or 110, transfer units are two bytes in size. Otherwise, transfer units are four bytes in size.