Hidden codes in NEC 8080A

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Wed Jul 24 15:49:01 2002

>From: "Eric Smith" <eric_at_brouhaha.com>
>Dwight Elvey wrote:
>> I started to look and see what hidden
>> codes might be in this processor.
>Is that different than what an Intel 8080A does?

Hi Eric
 I'll have to try it out. I'm not sure how
the intel ones respond.
>The undefined opcodes of the Intel 8085 are
>rather more interesting, I'm told.

 There were suppose to be a couple of block
move instructions. They put these in to
compete with Z80 ones but never released
them as part of the instruction set.
 This was why I thought there was something
extra in the NEC chip. I recall, way back when
I was working for Intel that we had a list
of the hidden operations that chips did.
I could swear that there was something in the
NEC 8080A that I'd confirmed by running
some code on my Poly-88. I guess my mind is
just playing tricks. The 8085 stuff is for
real, though. I don't have something easy
to test it on. The Poly-88 has a great monitor
that I can single step with and examine every
 I think I have a 8085/8088 S100 board around someplace.
Maybe for future fiddling I'll see what it does.
If I think of it, I can check the intel 8080A tonight.
Received on Wed Jul 24 2002 - 15:49:01 BST

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