Open

a request to open the parallel port

This function allows the requestor software access to the parallel device. Unless the shared-access bit (bit 5 of io_ParFlags) is set, exclusive use is granted and no other access is allowed until the owner closes the device.

A FAST_MODE, can be specified (bit 3 of io_Parflags) to speed up transfers to high-speed printers. Rather than waiting for the printer to acknowledge a character using the *ACK interrupt, this mode will send out data as long as the BUSY signal is low. The printer must be able to raise the BUSY signal within 3 micro-seconds on A2630s, otherwise data will be lost. Should be used only in an exclusive- access Open().

A SLOWMODE mode can be specified (bit 4 of io_ParFlags) when very slow printers are used. If the printer acknowledges data at less than 5000 bytes per second, then this mode will actually save CPU time, although it consumes much more with high-speed printers.

The PTermArray of the ioExtPar is initialized only if the EOFMODE bit (bit 1 of io_ParFlags) is set. The PTermArray can be further modified using the PDCMD_SETPARAMS command.

"parallel.device"

a pointer to literal string "parallel.device"

unit

Must be zero for future compatibility

ioExtPar

pointer to an IO Request block of structure IOExtPar to be initialized by the Open() function. The io_ParFlags field must be set as desired.

flags

Must be zero for future compatibility

d0

same as io_Error

io_Error

if the Open succeded, then io_Error will be null. If the Open failed, then io_Error will be non-zero.

exec/CloseDevice