Can't print PDF files on postscript printer

I have a postscript laser printer that prints everything except PDF
files. Anyone know what the deal is with PDF files? What makes them so
troublesome to print? Anyone know of a fix?

The laser printer that I have is a 1987 QMS-PS 810 (postscript level 1)
with 2 MB RAM memory (for print jobs, I guess) and 1 MB ROM memory (3
printer emulations and 35 resident fonts). I'm running Windows 2000 with
512 MB memory. Everything else prints fine, but when I try to print a
PDF file, the print job initiates but then fails. Instead of the
expected output, the printer will print an error message. Error messages
vary. Here are three typical:

1:
ERROR: interrupt
OFFENDING COMMAND: ISOLatin1Encoding
STACK: (long list of /items)

2:
ERROR: VMerror
OFFENDING COMMAND: dict
STACK: (long printout of postscript gibberish)
(From what I've found, the VMerror indiates virtual memory full, printer
out of memory, something exceeds the postscript interpreter's memory or a
postscript language line in it.)

3:
This job requires more memory than is available in this printer.
Try one or more of the following, and then print again:
For the output format, choose Optimize for Portability.
In the Device Settings page, make sure the Available Postscript Memory
is accurate.
Reduce the number of fonts in the document.
Print the document in parts.


So, I've done everything I can find to do; Set optimize for portability,
confirm memory set at 2 MB, print one page at a time, etc. Still can't
print PDF documents. If lack of memory is an issue, the 2 MB memory
works for everything else, why isn't that enough for PDF files?

Has anyone run into this before and found a solution?