Hidden codes in NEC 8080A

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Thu Jul 25 11:44:00 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
 First, there was an error in my previous list.
The 0D9h does a RET and not a CALL.
 I looked at a Intel 8080A last night. All of
the codes seemed to do the same. The values
in the PSW were different. On the Intel part,
bits 5 and 3 always returned '0' while bit
1 always returned '1'. Compared to the NEC
that always returned '1' on both 1 and 3
but had the -/+ on bit 5.
Dwight


>
>The undefined opcodes of the Intel 8085 are
>rather more interesting, I'm told.
>
>
>
>
Received on Thu Jul 25 2002 - 11:44:00 BST