A seach of the Web yields numerous hits on "NEC APC", many of which are
from cable companies. You should have no difficulty in
finding cables for
the computer.
I can tell you that the APC indeed belongs in your museum! If there ever
was a machine which stood out as before its time, that is the NEC APC. The
monitor was high resolution color (I hope you got the color version) at
about 640x480 if I recall. It had a dedicated graphics chip which could do
line drawing, curves, etc. It had about a 102 key keyboard. It had a 1MB
floppy (8", of course). It had a sound chip and integrated speaker capable
of reasonable music. Does yours have a hard drive? The early hard drives
were 10MB externals, by the way, so you no doubt have some kind of external
connector for that as well.
Many of these advanced features later (or much later) were added to the PC.
IBM eventually came out with EGA, which nearly matched the APC. With the
AT they nearly matched the APC's keyboard (though they still neglected
putting an "ENTER" key on the keypad), and surpassed the APC's floppy
capacity. It took many years though before the PC added sound cards with
better capability than the APC, or graphic accelerators with dedicated
graphics chips.
Too bad that your APC didn't come with documentation. The APC shipped with
the best documentation I have ever seen, including internal schematics, a
decription of all internal logical features, and a even a full listing of
the BIOS on a disk. The documentation allowed me to write for example an
interrupt driven print routine to replace the timing based BIOS print
routine. Using my print driver the APC was capable of fully driving a
300LPM printer, or capable of driving a 100cps printer while simultaneously
doing a program edit. Try that on an early PC!
I hope you got some software. The original disk included a program "BACH",
which demonstrated its musical prowess. Later machines shipped with a
simple program I gave to NEC called "PLAY" which allowed the machine to
play music coded into a text file which listed the notes to be played and
the duration of each note. Usage was "PLAY filename". Banjo music worked
particularly well. There was also an impressive program that demonstated
its color graphics potential.
Carl