So I've just coded the PER instruction in my 65816 assembler (which calls it phe.r), and am trying to confirm that I've done it right, and as part of that I'm checking it against the WDC Programming Manual. On page 172, we find Fragment 11.13, which looks like this (some secondary stuff deleted): Here's my problem. The PER instruction starts at $2200, and is three bytes long. So the next byte after it is $2203. If I understand what it is supposed to do, we now need the offset to DATA1, which is at $2503. In my world, this is is an offset of $300, and the PER instruction should come with that as the operand, making the whole instruction 62 00 03 in machine code. Instead, we have this weird 62 FD 7F I can't get my head around. $7FFD looks like the data from DATA2 and DATA3 minus 2, but I have no idea how that is supposed to get up there with PED. It doesn't even make sense as PEA (my phe.#).

Interestingly, the text above the fragment walks you through this example and actually says: except that in that example, the number following the opcode is $7FE1. Strange. $300 happens to be what my assembler is saying, by the way, so I'm obviously biased.

At the moment, I'm assuming this is another one of the many, many, typos in the Manual. I've started a Erratum at https://docs.google.com/document/d/1DMB ... sp=sharing , unless there is one already?

I'd say it's pretty obvious they have an error there. At first I figured it was just because you have not downloaded the improved manual that was a scan and OCR of the original paper one and came out a couple of months ago, because that fragment is on page 223 of my paper one; but surprise--the paper one has the same error. When you're not sure though, it's always good to go to the "The Instruction Sets" section that starts on page 421 and has at least a full page dedicated to every instruction. The full-page detailed description of PER is on page 475.

_________________
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The "second front page" is http://wilsonminesco.com/links.html .
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My assembler generates this

WDC has used the values stored at DATA1/DATA2 in the PER instruction rather than its address.

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Andrew Jacobs
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viewtopic.php?f=2&t=2639&p=29489#p29489

Mike B.

Ah, Mike, sorry, hadn't seen that.

Just out of curiosity, what is the official, newest, corrected version of the Manual? I'm using the "Copyright 2007" text version. The one now linked to on their website seems to be in a scanned book format, far less useful with small pages.

EDIT: I've added this to my Erratum

The offset being computed by your assembler ($0300) is correct.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

I have the OCRed version as well as the older PDF that used to be on the WDC site. Both have the identical error.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

I have not taken the time to do an A/B comparison through much of the different versions, but although I've been recommending the manual for years, I began sensing that the one they had online had problems, when I would have my stickies and notes in the paper one and I would try to direct people's attention to the same part of the electronic version. Then in the spring, WDC said they scanned and OCR'ed that paper one to take care of various problems, and posted it. Since it is OCR'ed, you can search it, mark blocks and copy text out of it, etc.. I seem to remember the paper one had sections that were not in the earlier online one.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?