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Retrocomputing

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    I think the last para explains something important fpr the OP: these weren't considered CPU's at the time; they weren't made to power microcomputers. They were microprocessors for "smart" devices. Commented Sep 21, 2020 at 1:38
  • I am not convinced by the "not enough logic" argument. A "slow multiplier" can be implemented by iterative shifts and conditional adds. The amount of microcode and extra logic to do this is much less than handling interrupts. And yet, many chips chose to implement interrupt handling but not multiplication. Your last paragraph is more relevant: multiplication wasn't needed for most applications. Commented Sep 23, 2020 at 17:26
  • @DrSheldon The designers didn't even budget for 16 bit arithmetic on the 6502, or DSUB to DADD on the 8080. Numerous things seem missing from both designs in hindsight, and multiplication is one of them, but fairly far down the list. Commented Sep 23, 2020 at 21:04
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    @RETRAC: The 6502 does perform 16-bit address arithmetic, including logic to skip the high-byte computation when adding or subtracting zero. Commented Sep 29, 2020 at 20:19
  • @supercat: and yet they didn't have the transistor budget to connect most of that logic up to make it available in the instruction set. Which would come before a multiplier as a design priority in most cases, I figure. Commented Sep 29, 2020 at 20:38