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Comment Re:Oldest? (Score 1) 79

cool link! (at least if you disregard things I remember being cast as ancient history!)

the 8080 had at least one or two undocumented instructions that worked their way into code. IIRC, the Heathkit chess program needed a byte changed from that to a documented instruction on the Z80 to run [a one byte patch!].

And there were a pair (?) of quirks where 8085 instructions took a cycle ore or less than the the same instruction on the 8080.

The Z80 executed some instructions in less cycles than the 8080 (but wasn't there one that took an extra cycle for some reason?

Comment Re:Oldest? (Score 1) 79

it was slow, but could be extremely low power compared to the others, and was silly-rich with registers. 16 general purpose 16 bit registers, iirc. (or pairs of eight bit). And ISTR that you could use all but one or two for program counter and reference (a pair of four bit registers [P & X ?] that pointed to which 16 bit to use]

Also, significantly more radiation resistant than the others of the time (or was that another version? Even so, its design should have been more resistant).

My first computer was a wire-wrapped 1802 . . .

Comment Re:Hot Rod Z80 (Score 1) 79

My guess would be that 24 bit address space for the MMU, and that this worked better with the Z80.

There were ways to extend the 6809 space by a couple of bits, but not by eight.

The greater abundance of registers on the Z80--including an entire second set of the 8080 registers, which could be toggled between--sounds like a likely reason. IIRC, the 6809 didn't have any extra data registers as compared to the 6800.

hawk

Comment Re:Screw the American auto industry (Score 3, Insightful) 303

The US auto industry competes just fine at building what Americans want to drive. The challenge comes in switching over to building what the American government wants Americans to drive. They are far from the same thing.

$70k trucks with beds smaller than a the same model from 30 years ago and $100k SUVs with the all styling of a brick. https://www.caranddriver.com/j...

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