[sdiy] HMI-200 8051 ICE Ext. Clk

[Gordonjcp]

On Wed, Oct 12, 2016 at 01:57:53PM -0700, MTG wrote:
> It must be the HR16 that is scrambled then. Some other manufacturers
> did this too. I don't know if it was for layout reasons or to
> obfuscate the EPROM code.

The lower eight bits of the EPROM address on the HR16 are flipped end-for-end so D7 becomes D0 and so on.  This was widely described as "encryption" among the circuit-bending types, but that's plainly nonsense.

It's quite obviously done to make it easier to route the board.

-- 
Gordonjcp MM0YEQ