Unknown 8085 opcodes

allison ajp166 at verizon.net
Wed Jan 11 15:26:07 CST 2017

On 1/11/17 12:19 PM, Charles Anthony wrote:
> On Wed, Jan 11, 2017 at 9:10 AM, Adrian Graham <binarydinosaurs at gmail.com>
> wrote:
>> Hi folks,
>> Any 8085 assembler geeks in the house?
> A uProcessor geek, but not 8085 :(
> However, Wikipedia mentions:
> " Undocumented instructions
> A number of undocumented instructions and flags were discovered by two
> software engineers, Wolfgang Dehnhardt and Villy M. Sorensen in the process
> of developing an 8085 assembler. These instructions use 16-bit operands and
> include indirect loading and storing of a word, a subtraction, a shift, a
> rotate, and offset operations.[7]
> 7. Dehnhardt, Wolfgang; M. Sorensen, Villy (January 1979). "Unspecified
> 8085 op codes enhance programming". Electronics. McGraw-Hill: 144–145. ISSN
> 0013-5070."
> -- Charles
I geek 8085 and Z80.  When you see a mess like that its sure bet to look 
at it with
a text analyser or DDT like tool that will display the code as text if 
it is.

PC people would not think to do that as its rare for them to see 7Bit ASCII
and the tools commonly used might not either.

The tool I use for that is Resource (8080/8085 intel mnemonics) or Zesource
(z80 mnemonics) and dis48 for 8035/48/39/49.  They run under CPM so you
need a system or an emulator like MyZ80 or Dave Dunfields 
Altair/Northstar emulator.
Resource and its kin are directed disassemblers and when done they do 
assemble back to the binary.

FYI if you want to see tightly packed code the TU58 controller (8085 based)
is a good example as it all fits in a 2K Eprom and only 256 bytes of ram.


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