[Coco] Branch Instruction Summary

[Sean Conner]

It was thus said that the Great Allen Huffman via Coco once stated:
> On Jul 22, 2025, at 1:16 PM, John Mark Mobley via Coco <coco at maltedmedia.com> wrote:
> > 
> > All,
> > 
> > See attached. I hope the attachment works.
> 
> I feel this would be very useful to me, with a bit more explaining. I have
> never really visualized how some of these other OP codes work with setting
> carry or Z or whatever. I know this is all embedded in the OP code
> references and such, and maybe I would understand it today, but I sure
> didn’t back in 1984.

  Here's the chart I found.  Plain text, and it (to me) explains when to use
what branches:

  +-----------------------------------------------------------------------+
  |                        6809 BRANCH INSTRUCTIONS                       |
  +-------------+-----------------------------+---------------------------+
  | Instruction |         Description         |     Condition Formula     |
  +-------------+-----------------------------+---------------------------+
  |   BCC/BHS   | Higher Or Same              |             XC            |
  |   BCS/BLO   | Lower                       |              C            |
  |     BHI     | Higher                      |            XC*XZ          |
  |     BLS     | Lower Or Same               |            C + Z          |
  |     BNE     | Not Equal                   |             XZ            |
  |     BEQ     | Equal                       |              Z            |
  |     BGE     | Greater Or Equal (Signed)   |          N*V + XN*XV      |
  |     BLT     | Less Than (Signed)          |         N*XV + XN*V       |
  |     BGT     | Greater Than (Signed)       |       N*V*XZ + XN*XV*XZ   |
  |     BLE     | Less Than Or Equal (Signed) |       Z + N*XV + XN*V     |
  |     BPL     | Plus (Positive)             |             XN            |
  |     BMI     | Minus (Negative)            |              N            |
  |     BVC     | Overflow Clear              |             XV            |
  |     BVS     | Overflow Set                |              V            |
  |     BRA     | Always                      |              1            |
  |     BRN     | Never                       |              0            |
  +-------------+-----------------------------+---------------------------+

  The top four branches are unsigned.  I don't even look at the condition
formula (but it was handy when writing my own emulator---here X means NOT).

  -spc