PowerPC For Dummies: A simplified guide to understanding the PowerPC Instruction Set
Thanks! Although I have a few counter questions.

So this part is actually correct?

With Update = An address will be placed into a register after execution of an instruction.

Algebric = The user specified value in an instruction will be treated as a 32 bit value.

Indexed = Calculates an address after execution of an instruction

I sent the page to one of the people who helped with the guide (and is familiar with PowerPC) to get his input, but he never responded when I sent him these, what I wrote for those are mostly assumptions, are those the actual definitions?


An Fyi. Li is a simplified mnemonic for addi

i.e. li r1, 1 = addi r1, r0, 1 #Broadway treats r0 as literal 0 when it's used as a source register in this instruction
Do you know what specific instructions treat r0 like this? I want to label them for the guide. 
(I know in the sentence below you say that there are too many to list, but what are the main ones?)


In the Broadway manual i see nothing about bun, bnu, bdznt, bdnzf, and bdz branches. Are these present in other PPC chips? An fyi, the disassembler used in Dolphin is a generic PPC disassembler, so it will show instructions that simply don't exist in Broadway. Maybe these are simplified mnemonics not referenced in the manual?

Not a question. But look at page 523 - 526 of this pdf. There are many, many, many, many.... many.... many... branch instructions types........


r3 = 0x80000000; VALUE = 0x1500
stwu r0, 0x1500 (r3)
Before instruction was executed; r3 was 0x80000000
After instruction has executed; r3 is now 0x80001500

In this context, what is r0 for? I've never really fully understood the "update" instruction types.


Your definition for NOT is incorrect. NOT is not the negative of a value. Its a simplified mnemonic for NOR'ing a register with itself

Hmm, well the person I've been showing the page to told me it made values negative. But what exactly does it mean to "NOR" a value? I only know of the term of it.


Regarding your quick description of an fpr, you should add in a note that the floating value is in its 64-bit form

I was going to put something like this, but on the psq description page on the smash forum I linked in another forum category here, it mentions that dolphin has a weird issue where it will display the same value twice in the fpr display in debug mode, even if it's not a double, something like that. It confused me, which means it most likely will confuse everyone else.


Bit is not a single digit within a word (its not half of a byte).

What would be a better term I could put for what I labeled as a "bit" on the site?

Last Question


On the Operation Instructions Section of the site
What I put for AND and OR is actually correct? I just want to be sure, the person I've been showing the site too didn't respond about it yet.

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RE: PowerPC For Dummies: A simplified guide to understanding the PowerPC Instruction Set - by JimmyKazakhstan - 06-27-2021, 04:22 AM

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