I Need a DOS-Compatible Laser Printer

There is no such thing as "DOS compatibility" as there never were any printer drivers for DOS. It was up to each and every application to know how to drive printers.

Having said that, most DOS applications send simple text to the printer. Printers that support PCL5 will happily print that. If the application also knows how to send PCL commands to change fonts etc, so much the better. As your old HP 4100 worked that implies that the app either sends text only, or text with some PCL commands. Again, any PCL printer will work.

The next issue is the interface. Most DOS apps insist on printing to LPT1. That means you need a printer with a parallel port. You can also get a networked printer and redirect the network port to LPT1. DOS does not know USB, but a USB port can be redirected in the same way as a network port. However, networked printers are far preferred over USB for business use.

At the low end, something like the Samsung ML-2855ND will work happily, but has no parallel port, network only. The HP P2035 does have a parallel port; the P2035N replaces it with a network port. These are just examples; as I said, just about any PCL printer will work fine for you.

I picked up an HP 4100 from Ebay with 12,000 pages on the engine for $250 for my house.  We still use HP 4000/4100s here at work: they are easy to get parts for and are super reliable.  Just a thought...

MASQUERAID:
Actually, I spoke to two people in VAR tech support, and they could not answer my question. I WAS surpised - and the reason I'm asking here now.

ALEINSS:
I thought of that (and have done so in the past). However, these printers are getting so old that it is a crop-shoot today finding one that doesn't have dried out rollers, regardless of the page count. By the time I paid for a used printer and had the rollers replaced ... well, a new P2055 looks pretty attractive IF it will work.

HDHONDT:
Sorry, I could have been more specific. My standard test for DOS compatibility is to type the following at a DOS prompt:
COPY CON LPT1
THIS IS A TEST
^L^Z

Because the P2055 does not have a parallel port, it would need to be shared and attached to LPT1 first:
NET USE LPT1 \\{PC Name}\{PTR Name}

I am hoping someone here has a P2055 and can do this test.

I had looked at the P2035 (because it has a parallel port), but it is host-based and I am relatively certain it would not respond to DOS commands despite the parallel port.

It will work with the commands you listed (COPY & NET USE)

The P2035 supports both GDI (host based) and PCL5e. See:

http://tinyurl.com/6o37v8