www.micro-examples.com

[BrunoG]

If you have any clue to this :

http://www.micro-examples.com/public/microex-navig/doc/087-pic16-secret-opcode.html

don't hesitate to leave a message !

Thanks,
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BrunoG, Administrator

[Ford]

I have recognized 4 opcodes from "mysterious" list.
It's standard instructions (but not recommended for future use):

0062: OPTION
0065: TRIS 5
0066: TRIS 6
0067: TRIS 7

No big treasure, do you?

Ford

[BrunoG]

Hi Ford,

well spotted

I will try this and add you to the list if it works , you will be the very first.

The big treasure if any is still to be discovered
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BrunoG, Administrator

[Ford]

> I will try this and add you to the list if it works
Why??

That's well-known instructions, Microchip described it all in old datasheet (now only states, that it became unrecommended). You can try MPASM, it normally produce these opcodes.

Second, I tried mysterious 0x3B <literal> opcode, and it seems, that it works the same as 0x3A (XOR). Can you reproduce and confirm that?

Ford

[atferrari]

Hola Bruno,

This is my first post here and, might be, probably you will not appreciate this, but it comes from personal experience:

Years ago I was happy (and had the feeling of owning an incredible secret ) after running across a list of the "secret" codes of the Z80. I spent quite some time on that.

To make short a long story, the Z80 is long time gone (at least from my life) and the list is lost somewhere...

Never could do anything useful with them when actually programming the Z80.

The same happened when finding incredible things to do with not declared or "reserved" positions of RAM in the Sinclair ZX81. Just NOTHING.

I asked about them (for the Z80) and in general for all micros in several forums, years ago: more or less, all coincided: Yes, they exist but who is going to use them in any formal design considering that Zilog, (or whoever) did not endorse them offcially?

In three years time I dare to say, you will find that I was right. Time is the only thing you can not recover. If you (and all the guys involved in that) finally do not agree, it's yours / their time after all.

Il-y-a meilleures chosses à faire, je crois. Quand même, plus outiles.
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Agustín Tomás
In theory, there is no difference between theory and practice. In practice, however, there is.

[DataMatrix]

PICs are RISC controllers and I'm sure you all know that. All the instructions stated in the official datasheet are based on the CPU's design itself - they are all build on hardware basis with transistors and etc. I'm pretty sure, that microchip wouldn't design instructions on cpu level and then just hide them from the developers. All "hidden" instructions are just deprecated opcodes from previous designs.
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