CBM MOS 1351 controller chip


Recommended Posts

Hi Im new to FPGA but have one question:


Concerning Commodore MOS chips

Is there open source for:


1351 Mouse Controller

C64/C128 Ram chips

REC memory controller

SID: 6581,6582,8580 last known revisions?


The last item is: I have heard that CBM MOS chips could possibly be redone using xilinx

using PLD but its difficult but would any of the Papilio code still work with Xilinx software?


Is there any open source for anything like the CBM MOS 1351 controller chip.

(1351 was CBM Mouse, worked in Joystick Mode and Proportional mode). 

Other controllers wont work because the 1351 somehow worked along with the SID Oscillator, without that it

wouldn't work.


I hope I asked this in the right forum so any help is appreciated.


Thank you,


Terry Raymond


  • Like 1
Link to comment
Share on other sites

I believe there's an open source recreation of one of the SID chips, used in the RetroCade Synth project.  There may be ones for the other chips, but they wouldn't be found here.  I'll list places I'd recommend looking, at the bottom of this post.


But note, these are not the original chips, but new designs that try to replicate the behavior of the old chips.  I expect the original chips' actual designs are long gone.  And these re-creations may be imperfect; and many are likely to differ in details of external interfacing.  Thus, they would not be drop-in replacements if that's what you're looking for.


Regarding Papilio and the Xilinx software:  The Xilinx software is used for building many of the Papilio projects as it is.  But I'm not clear what you're really asking.


Regarding PLD:  If you mean CPLD, I haven't worked with them, but I think their capabilities are a lot less than FPGAs and that might be a problem when trying to get complicated designs to work.


Places to look for open source re-creations of these chips, or related information:

http://opencores.comhosts a lot of open source designs.

http://www.visual6502.orgreverse engineers a lot of old chips.

ftp://www.zimmers.net/pub/cbm/documents/projects/interfaces/mouse/Mouse.htmlhas a lot of info about the Commodore 1351 mouse.

https://twitter.com/MEGA65Retrois a project for creating a sort of "super commodore" machine on an FPGA, they may have worked on including related functionality.

Link to comment
Share on other sites

There is at least one open source C64 implementation in FPGA, so that will replicate the functionality of any of the chips in that machine. It lacks the SID filters but they are implemented in the Retrocade Synth project so it should be possible to port them.


As far as RAM chips, most retro computer projects use static RAM, rather than trying to exactly duplicate the original architecture.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.