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Programmer's Guide PcOS Series 150 Communications
Parallel Port
12/14/99 Rev G Page 111
Printer Buffer Size
The Series 150 Printer has a configurable buffer size. It can be set from 256 bytes to 6144 bytes.
This allows an application to control how far ahead of the printer it can get. The smaller the
buffer is, the tighter the control will be. It is up to the application developer to select the optimal
buffer size.
One-line mode
The Series 150 Printer supports a one-line mode of operation. In this mode, the input buffer
is set to 1024 bytes; however, the printer will go busy after every [CR] received. In this
mode, the printer will stay busy after the [CR] is received and remain busy until the previous
information is printed. Several features must be considered when using one-line mode.
1. The printer only looks at [CR]’s. [LF] will cause the printer to print but will not set
busy.
2. If a [CR] character is received as part of another command, i.e, as part of graphics data,
the printer will go busy after the [CR] is received, but will go ready after the [CR] is
processed.
3. By definition, one-line mode is slow. The printer will not allow the application to get
ahead of the printer.
Parallel Port Inquire IEEE 1284
The Series 150 Printer supports the IEEE 1284 bidirectional parallel peripheral interface
standard. This standard provides for a bidirectional link on the parallel port. The Series 150
Printer supports Modes 0 and 4 only. This provides a nibble mode reverse channel for printer
identification and status inquire command. It is beyond the scope of this guide to describe the
IEEE 1284 protocol. The complete specification is available from:
The Institute of Electrical and Electronic Engineers, Inc.
345 East 47th Street
New York, NY 10017, USA
Buffer
The Series 150 Printer has a 256-byte buffer that contains information to be returned by the
IEEE 1284 reverse link. Information is placed in this buffer in the same format as RS-232
serial information is returned.
Inquire commands sent to the printer in IEEE 1284 mode will place responses to the
commands in the IEEE 1284 reverse channel buffer. This buffer is then transmitted to the
host when the host requests the reverse channel.
Mode 4
Mode 4 provides for the printer to return identification information to the host system. The
Series 150 Printer returns:
xx,yy (length of following data, 2 bytes with msb first)
MANUFACTURER: Ithaca-Peripherals;
COMMAND SET: IPCL;
MODEL:150;
COMMENT: Rev. x.xx;
ACTIVE COMMAND SET: IPCL;