My old trusty DEClaser 5100 (aka: HP Laserjet 4+ with DEC software) has
a PPD file. I found out that the PPD is "too old" for the new CUPS
software on the MAC.

You can test PPDs for version 4.3 compliance at:

Anyhow, I managed to update the PPD to appear to pass the tests. But I
am still having some problems with the Mac GUI printer setup not
honouring the UIConstraints properly (can't enable the decimage Punch
unless you check the DecImage box first, and this isn't working
properly, although on the CUPS web interface, this seems validated
properly when you click on the "continue" web button.

I haven't actually printed anything with it yet. But I was having
problems with the command line printing (lpr) adding junk that redefined
the "showpage" to be a no-op which caused a raw postscript file to
overlay all its poscript pages onto a single page :-)

BTW, turns out that under CUPS, you can LPR a text file to a postscript
printer and it will automatically convert it to postscript for you.
(this is on a Mac, Tiger, but I suspect that on Linux it would do the same).

If anyone else still has a DEClaser 5100 and wants to use it on a Mac or
Linux, send me an email and I might send out the updated PPD file.