NAME

tek − Tektronix 4692 color graphics printer device

SYNOPSIS

device ik0 at mb0 csr 0x70c0 priority 5 vector ikcintr

DESCRIPTION

The Tektronix 4692 is a color hardcopy device with automatic dithering.  It is capable of printing an image of 1536 by 1152 pixels on 8½ by 11 inch paper or transparencies, each pixel being a combination of one or more of the primary colors or black or white.  The Ikon 10085 controller is used is used to drive it.  An image takes approximately 1½ minutes to print, including paper loading and unloading time. 

The device file, /dev/tek, interprets the supplied data as appropriate for driving the Tek 4692.  A high-level graphics routine, capture(3G), is also provided to allow capturing the current IRIS console screen image and printing it. It uses a network spooling system, colord(1), so that users on different systems can spool up images over XNS for printing at workstations with Tek 4692 printers.

Additionally, the utility program capture(1G) is supplied which invokes the capture graphics routine and sends the output to the specified destination. Low-level routines, coloropen(), colorwrite(), and colorclose(), are also provided. These routines, which are documented in coloropen(3), allow a program to generate its own data and produce a printed copy using the network spooling system.   (The data to be printed does not necessarily need to appear on the screen.)

To write an image to /dev/tek, a header is first written to the device, using a single write. This header must be at least 6 bytes long.  Any data longer than 6 bytes is ignored, allowing for a 1024-byte write so that the data file can be blocked on 1024-byte boundaries.  The contents of these bytes is documented in the Tektronix 4692 Color Graphics Copier Device Driver Development Guide and summarized below:
 

The mode byte is broken up into several bit fields. Bit 0 is the low-order bit.  Set bit 0 to true to specify black and white inversion.  Black and white inversion means that white will be printed when the intensity of all colors for a given pixel is zero (normally black) and vice versa.  This inversion allows for the fact that the background color on many CRTs is black and the background color for the printer is white (blank paper). 

Set bit 1 (the "quality bit") to true to fix the image resolution at 158 pixels per inch. If bit 1 is false, then the pixels will be spread as needed.   The pixels can spread up to 128 pixels per inch. When the pixels are allowed to spread, the image takes up as much of the page as possible. 

Bits 2 and 3 specify the image orientation:
 

Bits 4 and 5 specify the image resolution in bits per color per pixel:
 

Bit 6 is the communications mode. The driver controls this itself.  Bit 7 must be true (so that this byte is recognized as data). 

Byte 1 is the repaint byte. The low-order three bits specify how many images should be painted on the same page.  These bits should normally be set to 0x01 for paper.  The count can be increased for transparencies since they generally require more ink. If the count is increased, then the complete image data, including the header, should be replicated.  In this case, the device file should be opened, written to, and closed for each repetition of the image.  It may also be used to superimpose several different images on the same page.  The repaint count should be ored with 0x80.

Byte 2 is the high-order 7 bits of the size of the x dimension, in pixels, ored with 0x80. Byte 3 is the low-order 7 bits of the x dimension size ored with 0x80.

Bytes 4 and 5 are, respectively, the high-order and low-order 7 bits of the y size, ored with 0x80.

The driver will supply the checksum and EOL bytes. 

Each subsequent write provides the data for one raster line (which is printed parallel to the long edge of the paper). For producing images of 1 bit per color per pixel, two pixels are supplied in each byte so each write must be of 512 bytes to specify a full line of data.  For 2 bits per color per pixel, each pixel takes up one byte so each write must be 1024 bytes to specify a full line of data.  Likewise, for 4 bits per color per pixel each pixel takes up two bytes and each write must be 2048 bytes to specify a full line of data. 

If a write contains less than an entire line worth of data, then the last pixel value will be replicated. This can be useful for data compression.  At least one pixel per line (two pixels for 1 bit per color per pixel) should be specified.  After writing the data, the file must be closed (to cause paper ejection).  If less than the full number of lines are specified, then the rest of the paper will be blank (white). 

The data format for encoding each byte for 1 bit per color per pixel is as follows (assuming two pixels are packed into each byte).  The high-order two bits (bit 6 and bit 7) must be true.  The low-order three bits (bit 0, bit 1, and bit 2) are for the n-th pixel, and bit 3, bit 4, and bit 5 are for the next (n-th plus one) pixel.  Of each three-bit triplet describing a pixel, the low bit specifies red, the middle bit specifies green, and the high bit specifies blue. 

The data format for encoding each byte for 2 bits per color per pixel is as follows.  The high-order two bits (bit 6 and bit 7) must be true.  The low-order two bits (bit 0 and bit 1) are for the red value.  Bit 0, the low-order bit, and bit 1, the high-order bit, specify the intensity level.  Likewise, bit 2 and bit 3 specify the green value, bit 3 being the high bit.  Bit 4 and bit 5 specify the blue value, bit 5 being the high bit. 

The data format for encoding each byte for 4 bits per color per pixel is as follows.  (Each pixel requires two bytes).  The encoding is similar to that for 2 bits per pixel, with the first byte of the pair specifying the high-order two bits for each color and the second byte the low-order two bits. Bit 6 is true for the first byte of the pair and false for the second byte to distinguish them. 

FILES

/dev/tekformatted Ikon device for Tektronix 4692

SEE ALSO

capture(1G), colord(1), capture(3G), coloropen(3), Tektronix 4692 Color Graphics Copier Device Driver Development Guide (Tektronix Part No. 070-4818-00)
 
 

Version 2.5r1  —  October 29, 1986