LP(4) — UNIX Programmer’s Manual
NAME
lp − Systech parallel line printer interface
SYNOPSIS
device lp0 at mbad? csr 0x400 maps 2 bin 4 intr 6
DESCRIPTION
The lp device driver supports the Systech MLP-2000 controller for line printers using the Centronics or Dataproducts parallel interfaces. It supports up to two line printers per controller. The standard controller names consist of “lp” followed by the controller unit number (e.g. lp0, lp1).
The unit number of the printer is specified by the minor device number. The standard device names consist of “lp” followed by the line printer unit number (e.g. lp0, lp1). Each device is exclusive access on open.
Each controller occupies 32 contiguous bytes of MULTIBUS I/O address space starting at the csr address.
CONFIGURATION
The default characteristics include aligning to top of form on open and close, 132 columns, and 66 lines per page. Lines longer than the maximum line length are silently truncated.
Each printer can be configured for special characteristics, including line lengths, column lengths, and special modes. The special modes are: upper case only mode and raw mode.
In normal mode, the driver interprets newlines, backspaces, tabs, and form feeds. Tab stops are every 8 columns starting at column 8 (i.e. 8, 16, 24...). Most printers can operate in both print and plot modes using the normal operation mode.
In the upper case only mode, lower case letters are mapped into upper case. Other characters are mapped to similar characters overstruck with “-” according to the following table:
| Input | Mapped to |
| { | - ( |
| } | - ) |
| ` | - ´ |
| | | − ! |
| ~ | − ^ |
Raw mode provides an eight-bit data path to the printer. Tabs, formfeeds, newlines and other special characters are not expanded, and no line or page adjustments are made.
The configuration options are specified in a table in the binary configuration file, /sys/conf/conf_lp.c. The first column specifies the line length. The second column specifies the number of lines per page. The third column specifies the mode. The printer characteristics are indexed by the minor number of the device. If the minor number is greater than the number of entries in the array, the configuration options for the last entry in the table are used.
For example, if you had the following hardware configuration:
| printer 0 | 80 columns | 25 lines | upper case only |
| printer 1 | 132 columns | 25 lines | raw |
| printer 2 | 132 columns | 96 lines | normal |
| printer 3 | 80 columns | 66 lines | normal |
| printer 4 | 132 columns | 66 lines | normal |
| printer 5 | 132 columns | 66 lines | normal |
you could use the following configuration table:
| struct | lp_printer | lpconfig[] = { | |||
| /∗ | cols, | ht, | special_map | ||
| ∗/ | |||||
| { | 80, | 25, | LPCAPS | } , | /∗ 0 ∗/ |
| { | 132, | 25, | LPRAW | } , | /∗ 1 ∗/ |
| { | 132, | 96, | LPDEFAULT | } , | /∗ 2 ∗/ |
| { | 80, | 66, | LPDEFAULT | } , | /∗ 3 ∗/ |
| { | 132, | 66, | LPDEFAULT | } , | /∗ 4 ∗/ |
| }; |
Note that the sixth printer (number 5) is not specified in the configuration but will have the same characteristics as printer number 4.
The default configuration is as follows:
| struct | lp_printer | lpconfig[] = { | |||
| /∗ | cols, | ht, | special_map | ||
| ∗/ | |||||
| { | 132, | 66, | LPDEFAULT | } , | /∗ 0 ∗/ |
| { | 132, | 66, | LPDEFAULT | } , | /∗ 1 ∗/ |
| }; |
BUFFER SIZE
The number of maps specified in the entry for the controller in the kernel configuration file determines the size of the data buffer. The maximum buffer size per printer is 8K bytes. Each printer is allocated half the number of maps specified for its controller (since each controller supports up to two printers). Each map results in 1K bytes of buffering. Thus in the example listed in the SYNOPSIS, each printer connected to lp0 has a 1K-byte buffer.
FILES
/dev/lp∗
/sys/conf/conf_lp.c
SEE ALSO
DIAGNOSTICS
None.
DYNIX