Dave W wrote:
On Mon, 25 May 2020 00:42:14 -0400, Paul
wrote:

Dave W wrote:
On Sat, 23 May 2020 01:07:58 -0700 (PDT), wrote:

I wonder if you know your options but don't want to accept them.
I have a new option now - construct a USB to parallel port inside a
Centronics plug housing, using an FT245BL chip.
Here is a summary, as to things your adapter could do.
This file is a PDF, and when it arrives, may need ".pdf"
added to the end of the filename.

http://www.prolific.com.tw/ShowProductPDF.aspx?p_id=6

(PL2305 http://www.prolific.com.tw/US/ShowPr...p_id=6&pcid=41 )

"The PL2305 is default to negotiate with the printer into

Nibble mode for upstream data and

Compatible mode for downstream data transfer."

Whatever that means.

Does every printer do it that way ???

Paul


I don't know what it means either, but the words "USB Printer Class
specification" seem to indicate that the chip is similar to all USB to
printer adapters, which use the Windows USB Printer service but do not
create a port like LPT1.

The printer service demands that the printer declares its name when
interrogated, and if it doesn't respond with a name in Windows' list,
then we get "Printer not connected" as one of the USB devices in
Device Manager.

If I have LPT1; I can send it print data for my printer from my BASIC
programme irrespective of whether it's the right printer.

As far as I know, this is mainly a Class driver limitation.

Perhaps the hardware supports more than the intended standard.

But I'm not aware of anyone crafting a different driver for the job.

I was just surprised, that the hardware admits to two modes,
as part of the job. The impression I got in the past, was
that these things use "1 of 4 modes", but the comments
never went into any details as to how that worked. Or for
that matter, whether all printers would work with such dongles.

I have an alternative here, as I have a PCI Express parallel port
card, which drives my JTAG cable (used with an FPGA kit). But
that's no good as a solution for someone with a laptop. ExpressCard
went out of style long ago, and they don't seem to ship laptops
with that any more. For laptops there are fewer options.
(If you have ThunderBolt or USB4, maybe some day you'll be
able to use an "external enclosure" with a parallel port card.
And that would likely mean an Apple computer as your base.)

Paul