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C64 <-> CS/A65 bus adapter

This is the description of an adapter to use most CS/A boards in a C64. A lot of CS/A boards, including a video card, serial interfaces, floppy controller and an SCSI card can be found on the CS/A65 homepage.

The interface itself is, in fact, pretty simple. It is a board that is plugged into the C64 expansion port. On the other side it provides a socket for a CS/A bus card. Two things have to be considered for the schematics:

  • The C64 Video chip releases the bus with rising Phi2. This is too late for the 6522. Thus the rising edge of Phi2 must be delayed to the CS/A bus, to be sure. The CS/A bus is specified to run up to 2 MHz, so there is no speed problem.
  • The I/O area in the C64 is 256 byte only. To cover the whole CS/A bus address space (1M memory and 4k I/O) additional address lines have to be generated. This is taken care of with a VIA 6522 on the adapter. More in the description.

  •  
    2006-12-16 Added an Eagle schematics board version.
 

Table of content

Version: 1.0C

Status: ok

Notes

 
This board only works with a C64 - not with a C128!
 
The layout could be better. If you have long plugs for the video and IEC, they may conflict with the CS/A card in the adapter board.

Version: 1.0B

Status: ok

Notes

 
This board only works with a C64 - not with a C128!

Files

 
c64csa.jpg
 
c64csadesc.txt
 
c64csaparts.txt
 
c64csa.png
 
c64csa.ps.gz
All Copyrights are acknowledged. The information here is provided under the terms of the GNU Public License version 2 unless noted otherwise.

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