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BigEd
 Post subject: Re: Breaking 6502 apart
PostPosted: Sat Jun 01, 2013 6:15 pm 
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Joined: Thu Dec 11, 2008 1:28 pm
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Location: England
These are individual columns of the decoder PLA, each being a big NOR gate. The IR is the Instruction Register.
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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Sun Jun 02, 2013 1:00 am 
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Joined: Fri Jun 22, 2012 7:39 am
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Yeap, and BRK2 / JSR3 are decoder line names. Number after opcode represent cycle, when this decoder line is trigger.

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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Mon Jun 03, 2013 7:51 pm 
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I almost completed top part on logic gates, and made some draft of it.

Don't look closely, it may contain typos and still not fully "de-morganized", just wanted to show you complexity and structural parts of it.

Bottom part will be done after top one.


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mos-6502-draft.jpg
mos-6502-draft.jpg [ 1.41 MiB | Viewed 1717 times ]

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BigEd
 Post subject: Re: Breaking 6502 apart
PostPosted: Mon Jun 03, 2013 8:38 pm 
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Bravo!
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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Thu Jun 06, 2013 8:44 pm 
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Todays speccy: ALU control

(I'm lazy to complete PLA lines, will be added later :P )

+fixed shortcut on ROR carry logic in transistor circuit.


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6502-alu-control.jpg
6502-alu-control.jpg [ 405.89 KiB | Viewed 1693 times ]
ALU_control.jpg
ALU_control.jpg [ 505.22 KiB | Viewed 1693 times ]

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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Mon Jun 10, 2013 9:17 am 
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Updated and cleaned up most of circuits on http://www.circuitlab.com

Need to add some missing parts of bus control and top part will be ready.
Image

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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Mon Jun 10, 2013 7:40 pm 
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Joined: Fri Jun 22, 2012 7:39 am
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Ok, I'm done with top part.

I isolated 6502 "core" and trying to understand how its executing, step by step.

Some slides below :)


Attachments:
6502_runflow_slide1.jpg
6502_runflow_slide1.jpg [ 1.69 MiB | Viewed 1657 times ]
6502_runflow_slide2.jpg
6502_runflow_slide2.jpg [ 1.78 MiB | Viewed 1657 times ]
6502_runflow_slide3.jpg
6502_runflow_slide3.jpg [ 1.84 MiB | Viewed 1657 times ]
6502_runflow_slide4.jpg
6502_runflow_slide4.jpg [ 1.97 MiB | Viewed 1657 times ]

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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Wed Jun 12, 2013 10:20 am 
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Joined: Fri Jun 22, 2012 7:39 am
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Updated transistor circuits. Fixed some errors and split it on two parts : top and bottom.


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6502_top.jpg
6502_top.jpg [ 2.08 MiB | Viewed 1634 times ]
6502_bottom.jpg
6502_bottom.jpg [ 1.37 MiB | Viewed 1634 times ]

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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Thu Jun 13, 2013 8:56 am 
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Joined: Fri Jun 22, 2012 7:39 am
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In last minutes I found missing part of DL/DB, will be fixed soon )


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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Thu Jun 20, 2013 7:50 pm 
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Todays speccy: ALU logic circuit

Later I maybe optimize SUM calculation, by replacing couple of NAND/NORs by XORs.
Don't want to mess with inverted carry chain ATM :)


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6502-alu.jpg
6502-alu.jpg [ 562.89 KiB | Viewed 1596 times ]

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whartung
 Post subject: Re: Breaking 6502 apart
PostPosted: Mon Jun 24, 2013 1:08 am 
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Hi org,

I just wanted to congratulate you on the 1 year anniversary of this project (I know, I missed it by a day). Hard to believe it's been a year, but here it is, and you're still going strong on it and making great progress from the looks of things (not that I have really any idea what I'm looking at).

But kudos to perseverance.
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BigEd
 Post subject: Re: Breaking 6502 apart
PostPosted: Mon Jun 24, 2013 9:30 am 
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Great progress indeed - happy yesterbirthday to the project
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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Tue Jun 25, 2013 8:39 am 
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Thank you, I really appreciated for your support ! :)

Within few days I'm going to complete whole 6502 logic circuit.

Today I experimented a bit with GIS applications, and adapted it for my task: http://breaknes.com/files/6502/tilemap/
This is tile map viewer of extra-large images, based on OpenLayers API.

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BigEd
 Post subject: Re: Breaking 6502 apart
PostPosted: Tue Jun 25, 2013 5:01 pm 
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I like it! (Did you see the 65CE02 post? There's a slippy map there of the die shot.)
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org
 Post subject: Re: Breaking 6502 apart
PostPosted: Wed Jun 26, 2013 5:27 pm 
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Todays speccy: Program Counter logic circuit


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6502-program-counter.jpg
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