Background

IBM 3800-3

The first AFP printer was the IBM 3800-3 delivered in 1983. It had a single, fixed media origin or top, left-hand corneras shown by the shaded rectangle in Figure Fixed Media Origins for the IBM 3800–3 Printer. Print data could be placed to print across, down, or up the page. Across and down are shown. Page definitions, (pagedefs), were used to place the line data on the page. IBM provided page definitions for common line spacings for both portrait and landscape orientation. The two most common paper sizes used were 12" x 8.5" (shown on left) and 9.5" x 11" (shown on right). As shown below different page definitions are required to print the same output on the two different sizes of paper. For example an across page definition is used to print landscape output on 12" x 8.5" paper and a down page definition is used for landscape output on 9.5" x 11" paper. Forms, like 12" x 8.5", that have a width greater than their length are referred to as wide continuous forms and forms, like 9.5" x 11", that have a length greater than their width are called narrow continuous forms.

IBM 3820

In 1985 the IBM 3820 was introduced. It was the first IBM AFP cut-sheet printer. Like the 3800-3, it had a single, fixed media origin as shown. The 3820 could print in the same directions as the 3800-3 plus one new direction, back. As shown below it had similar print direction characteristics to a 3800-3 using 9.5" x 11" paper.

The Problem

Many customers had both 3800-3s and 3820s. The 3800-3 was the fastest printer of its time at 215 impressions per minute. In order to achieve that speed it had to use the 12" x 8.5" paper. This paper had the additional benefit of reducing maintenance charges because the 3800s usage charge was based on the number of linear feet printed. The use of the shorter, 12" x 8.5" paper cost less per page than the longer, 9.5" x 11" paper. Unfortunately, when the 12" x 8.5" paper is used on the 3800-3 it causes an incompatibility with the 3820. As shown in the figure below the 3800-3 with 12" x 8.5" paper has a different media orientation than the 3820.

The 3800-3’s media origin is at the left end of the long edge and the 3820’s is at the left end of the short edge. Because of this different page definitions would be needed to print the same output on both printers. For example, in order to print landscape output an across page definition would be used on the 3800-3 and a down page definition for the 3820. This would require different page definitions to be specified for each printer.

Another Problem

AFP also provides the ability to print image data. The print direction coded in the page definition controls how the text data is oriented on the page. Unfortunately it has no effect on data contained within an image. In the figure below an image containing the word, LOGO has been placed on the 3800-3 and 3820 pages. It is oriented as desired on the 3820 but appears to be rotated 90 degrees counterclockwise on the 3800-3. In reality the image has not been rotated, the paper has. In order to compensate for this a special, rotated version of the image had to be built for use on the 3800-3 and care taken to use the proper version on both printers.

When IBM was developing its second, continuous forms AFP printer, the 3835, it was decided to develop a solution for the problem of different media origins between cut-sheet and continuous forms printers. The AFP architecture was enhanced to allow the media origin to be moved to any of the four corners of the paper. This function is called Set Media Origin and is controlled by a value in the form definition or formdef. This value is called the Medium Origin and is set using the Page Printer Formatting Aid (PPFA), PRESENT and DIRECTION parameters on the FORMDEF and COPYGROUP commands.