Browse Prior Art Database

One-Pass Intelligent Printer Data Stream Transform Technique

IP.com Disclosure Number: IPCOM000105322D
Original Publication Date: 1993-Jul-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 111K

Publishing Venue

IBM

Related People

Carlock, J: AUTHOR [+4]

Abstract

Disclosed is a technique to transform print datastreams (such as ASCII) to IPDS in one pass through the input datastream. IPDS* and other printer datastreams (ASCII for example) have some inherent differences that make a one-pass conversion difficult. If forced to implement this conversion with a two-pass design, it is probable that the print driver could not supply high-speed AFP printers with data fast enough to drive them at rated speed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

One-Pass Intelligent Printer Data Stream Transform Technique

      Disclosed is a technique to transform print datastreams (such
as ASCII) to IPDS in one pass through the input datastream.  IPDS*
and other printer datastreams (ASCII for example) have some inherent
differences that make a one-pass conversion difficult.  If forced to
implement this conversion with a two-pass design, it is probable that
the print driver could not supply high-speed AFP printers with data
fast enough to drive them at rated speed.

      In IPDS, all fonts required for a page must be loaded into the
printer before any text for the page can be loaded.  In ASCII
however, font requirements may be identified anywhere in a page
through ASCII controls such as "Emphasized Printing".  This is a
problem, since all fonts must be converted to IPDS and shipped to the
printer before any IPDS page data is downloaded.  For ASCII the
datastream may be scanned to ship all fonts first, and then a second
scan could convert and download the page data.  This technique,
however, could cause performance problems with high-speed printers.

      To implement the ASCII to IPDS transform in one pass through
the input file, the Data Buffer Queue module was introduced.  The
Data Buffer Queue module employs a data buffer queuing scheme.  The
converter module simply converts the ASCII datastream to IPDS, filing
buffers with either font or page data and sending them to the Data
Buffer Queue module sends all font buffers straight through to the
printer, and queues the page data buffers until the end of the page
is encountered.  At this point, all font buffers have been sent to
the printer, and the page data queue can be drained (all its buffers
shipped to the printer).  This normal mode of operation is
illustrated in Fig. 1.

      The Data Buffer Queue module must be able to perform its
function even in conditions where enough memory is not available to
queue an entire page of data.  This could be caused by either
inadequate memory in the PC, or a very data-intensive page (a large
image, for example).  When the Data Buffer Queue module encounters
this condition (the buffer allocation fails), it simply discards...