Hi Bob,
I searched the OKI specs for the C5510MFP:
http://www.oki.co.uk/fcgi-bin/public.fcgi?cid=125&pid=5&prid=536&pdflag=1This thing is a GDI printer, meaning it does not support any PCL or PS commands. This also explains why there is no Linux or Mac printer driver for it. You will never make it run on eCS unless someone figures out a windows printer driver "wrapper" a la GenMac for NICs... I don't think we'll see that in the near future.
Only because it's a network printer it doesn't mean that this solves driver problems. As you said: You ARE able to send data to the printer - but it won't understand it.
Interestingly, it seems that the C5550MFP *HAS* PCL6 and PS support. That also explains why Joachim said "I found a C5550 driver". I didn't follow that thread from the start, forgive me if you already told, but: Is there any chance for you to return that printer and go for a C5550 instead?
BTW: GDI printing is one of the most crappy inventions ever made, as it puts the processing requirements into your PC instead of the printer (the opposite of what one would expect from a "peripheral" device). If you take a look at some differences between GDI and "real" printers, you can see what it boils down to:
- GDI printers are cheaper in most cases
- GDI printers come with a lot more memory
- GDI printers support windows only
What this means (and where it comes from):
- no PCL or PS "licensing" required, no compatibility with it needed (dunno if there is a licensing for it at all)
- not much intelligence is in the driver as the windows GDI API functions ("screen") are used for printing too
- raw data from GDI is sent to printer instead of "printer control" commands (-> needs more printer RAM)
I think of GDI printing like a simple swap of the device context from screen to print while using the same GDI routines. Not sure if that comes close but that's what my understanding is...
If my understandding is more or less correct, the interesting question then would be:
If someone makes the same thing for the Presentation Manager GDI calls... would this give us almost instant GDI support in OS/2 and eComStation?
But this is something for people with more tech insight into windows and OS/2 driver and GDI stuff.
And BTW: CUPS isn't actually a printer driver but more of a spooler. At least that is what Peter Koller told me during side-talks at Warpstopck Europe. I guess he's quite renowned for having at least SOME expertise in matters of graphics...

He's got an OKI color laser printer too BTW... I am not sure but think that he is thinking about digging into these ever-ongoing printing (driver) problems using an entirely different approach. Unfortunately while sounding very promising, the idea would mean a huge amount of work... with no guarantee that it will do a specific job...
Really sorry to tell bad news...
Cheers,
Thomas