Re: [CAD_CAM_EDM_DRO] RE: BDI : Parallel Port Setup

Hi:

I think what you may find is that the computer may have a ECP type of
parallel port that will need to initialized before it can be used. This is
what was found by the DRO software people. The ECP port can be configured
as an old SPP (parallel port ) as a PS/2 port , EPP (Enhanced Parallel Port)
or a EMC bi-directional port. This means I think that the software will
need to be modified to send the necessary initialization sequence to the
card. Look at the documentation that came with the card. It should tell
you how to initialize it and what registers are what.



Here is some of the inline documentation to the DRO program as modified by
Robert Duncan.

"On many ports that support advanced modes, you can configure the port
either in the CMOS
setup, or with jumpers, or with configuration software that comes with the
port. Most have
an option that causes the port to emulate the original SPP, plus one or more
options that
enable the advanced modes. If the port is configured as an SPP, the advanced
modes will
be locked out and the port will fail any tests for PS/2, EPP, or ECP
abilities.

Detecting an ECP

In testing a port, you might think that the first step would be to test for
an SPP, and
work your way on up from there. But if the port is an ECP, and it happens to
be in its
internal SPP-emulation mode, the port will fail the PS/2 (bidirectional)
test. For this
reason, I begin by testing for an ECP, and work down from there. This is the
method
Microsoft's ECP document (in the Developer's Network CD-ROM) recommends for
detecting an
ECP: 1. Read the ECP's extended control register (ECR) at base address +
0x402 and verify
that bit 0 (fifo empty) =1 and bit 1 (fifo full) =0. These bits should be
distinct from
bits 0 and 1 in the port's control register (at base address + 2). You can
verify this
by toggling one of the bits in the control register, and seeing that the
corresponding
bit in the ECR doesn't change. 2. A further test is to write 0x34 to the ECR
and read it
back. Bits 0 and 1 in the ECR are read-only, so if you read 0x35, you almost
certainly
have an ECP. If an ECP exists, you can read and set the ECP's internal mode
in the ECR. "




__________________________
James (Jim) Buchanan
Lexington, Kentucky USA
Climax Class B Locomotive; Builder and Operator
Email: jambuch@...
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