Source : Free On-Line Dictionary of Computing

Commodore 65
     
         (Or Commodore 64DX, C65, C64DX) The last 8-bit
        computer designed by {Commodore Business Machines}, about
        1989-1991.  The C65 boasts an {ugly} collection of {custom}
        {integrated circuits} which makes even the {Amiga} hardware
        look standard.
     
        The core of the C65 {chipset} is the {CSG 4510} and {CSG
        4569}.  The 4510 is a {65CE02} with two {6526} {CIA}s.  The
        4569 is equivalent to a combination of the {6569} VIC-II and
        the {MMU} of the {Commodore 64}.  The C65 also has a {DMA
        controller} (Commodore's purpose built {DMAgic}) which also
        functions as a simple {blitter}, and a {floppy controller} for
        the internal {Commodore 1581}-like disk drive.  The floppy
        controller, known as the {F011}, supports seven drives (though
        the {DOS} only supports 2).  The {4510} supports all the {C64}
        {video modes}, plus an 80 column text mode, and {bitplane}
        modes.  The bitplane modes can use up to eight bitplanes, and
        {resolutions} of up to 1280 x 400.  The {palette} is 12-bit
        like the {Amiga 500}.  It also has two SID's (MOS 8580/6581)
        for stereo audio.
     
        The C65 has two busses, D and E, with 64 {kilobytes} of {RAM}
        on each.  The VIC-III can access the D-bus while the CPU
        accesses the E-bus, and then they can swap around.  This
        effectively makes the whole 8MB {address space} both {chip
        ram} and {fast ram}.  {RAM} expansion is accomplished through
        a {trap door} slot in the bottom which uses a {grock} of a
        connector.  The C65 has a {C128}-like native mode, where all
        of the new features are enabled, and the CPU runs at 3.5
        megahertz with its {pipeline} enabled.  It also has a C64
        {incompatibility mode} which offers approx 50-80%
        compatibility with C64 software by turning off all its {bells
        and whistles}.  The {bells and whistles} can still be accessed
        from the C64 mode, which is dissimilar to the C128's
        inescapable C64 mode.
     
        Production of the C65 was dropped only a few weeks before it
        moved from the Alpha stage, possibly due to Commodore's cash
        shortage.  Commodore estimate that "between 50 and 10000"
        exist.  There are at least three in Australia, about 30 in
        Germany and "some" in the USA and Canada.
     
        (1996-04-07)