BitSavers Posts CDC ICEM Documentation

BitSavers has just posted scans of Control Data Corporation‘s Integrated Computer-Aided
Engineering and Manufacturing (ICEM) Engineering Data Library (EDL) as used on the Control Data Network Operating System (NOS). ICEM was a minor player in the overall CAD market, but ICEM Surface gained a prominent position in car body design. You can browse the documents on BitSavers.

For an overall history of the CAD industry, I recommend David Weisberg’s online free book The Engineering Design Revolution.

Scanning Documents with Limited Colors for Optical Character Recognition

I scan a lot of documentation for BitSavers. Sometimes the documentation has a limited use of color, such as red text highlighting user input, and so-on. Eventually, scanned documents on bitsavers will be run through an optical character recognition (OCR) program. High resolution bitonal (on or off, single bit per pixel) images work best for the OCR process. However, scanning a document with limited use of color in bitonal form means that the limited color highlighting present in the original document is lost. This can be particularly confusing when the original document mixed highlighted text and black text in the same example. In this blog post, I’ll describe how I scan these documents in a manner that preserves the original limited use of color and also keeps the document ready for OCR.

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Stitching Partial Scans of Oversize Documents

Sometimes when I encounter vintage computing documentation, the source material I find is a photocopy of an original manual. Recently, while making one final trip to The Black Hole before it closed for good, I found a photocopied manual for a Tektronix 4953/4954 graphics tablet. The manual included the service information for the tablet. For Tektronix products of this period, the service information includes oversize pages that have schematic diagrams of the electronics. Because the manual was a photocopy, the person who made the copies attempted to get the entire diagram by placing various portions of the oversize sheet on the letter size copy area of the photocopier and making several copies to cover the entire diagram.

As I scanned the photocopied pages for BitSavers, I came to the last few pages and realized that they were pieces of a larger diagram. I used the free Microsoft Research ICE (Image Composite Editor) to process the pieces into a single unified stitched image. In the past I had tried the open source utility hugin, but it was always very tedious and time consuming to stitch together a single image from multiple scans. With hugin, I always had to perform several trial stitches before I had a composite that meshed properly from all my individual scans. With ICE, I simply drag the individual images onto it’s window and within seconds I have a high quality composite that I can save back out for inclusion in the final PDF.

See the results for yourself by looking at the last two pages of the Tektronix 4953/4954 Graphics Tablet Instruction Manual on BitSavers. You’ll notice that there are a few little bits missing around the edges of the individual scans; these are areas that are not present in the original photocopied pages.

Recent Additions to BitSavers

BitSavers is a preservation archive of documentation and software for vintage computers. It is run by Al Kossow, who is the software librarian for the Computer History Museum. BitSavers is a wonderful resource for both historians and collectors of vintage computing. You can subscribe to an RSS feed for the documentation or an RSS feed for the bits to be made aware of new additions to the archive. Two recent additions to the archive shed some light on early computer graphics products.

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