2024-03-02: The wiki ran out of disk space, so things were not working. This has been resolved by adding another 5GB of quota ;-) Thanks to Tim Lindner for reporting the issues. 2020-05-17: If a page gives you an error about some revision not being found, just EDIT the page and the old page should appear in the editor. If it does, just SAVE that and the page should be restored. OS-9 Al (talk) 12:22, 17 May 2020 (CDT)

Synchronous Address Multiplexer

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Synchronous Address Multiplexer

Supports the MC6809/HD6309 MPU interleaving memory access with the MC6847/MC6847T1 VDG and the dynamic RAM refresh cycles.


  • SN74LS783 / MC6883 - used in CoCo 1/2
  • SN74LS785 - used in CoCo 2B
  • SAM Accelerator - an accelerated SAM allowing RAM refresh during full double-speed clock mode on CoCo 1/2 (may require upgraded PIAs too)
  • SAMX4 - CPLD-based SAM replacement with additional 256K banking
  • TCC1014 1986 - the 1986 version of the ACVC / GIME replaces and includes much of the SAM functionality for CoCo 1/2 backwards compatibility support
  • TCC1014 1987 - the 1987 version of the ACVC / GIME also replaces and includes much of the SAM functionality for CoCO 1/2 backwards compatibility support