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The PARC VLSI Systems Design Area has purchased a color impact printer-plotter made by the Ramtek corporation, for in-house use for VLSI checkplotting and general color graphic printing service. It is our intent to make this printer available for use by the general PARC community, provided that the operating expense for it may be shared by its users. This memo is to request an appropriate sharing of the expense.

An impact printer-plotter forms characters and graphics with dots made by hammers pushing an inked ribbon against paper (somewhat like a typewriter). In the Ramtek 4100, there are four heads, each with a different colored ribbon and nine hammers. Paper is advanced through the machine by a tractor chain which meshes with holes along the edge of the paper. Ribbons and paper are the major operating cost of impact printers, with the cost of ribbon, available only from Ramtek, far exceeding the cost of paper, available on the open market.

Figures supplied by Ramtek indicate that from 60 to 180 copies may be expected per set of four ribbons, which cost $125/dozen ($41.67/set), yielding a per-page cost of $.23 to $.69. It is our expectation that with the rather heavy ink usage in VLSI and graphic plotting, costs may run near the high end. Paper (14-7/8" x 11" white unlined 20-pound tractor-feed fanfold paper) costs $48/box of 2400 pages, or $.02 per page. For approximate calculations we will assume a total cost of $.50 per page.

It is difficult to project the demand for such a new device. An upper bound may be obtained by examining the printer speed. A full page takes six minutes to print. Assuming 6 printing hours per day, 250 working days per year, the printer could print 15,000 pages per year. (Less than full pages print faster but use less ink; it is assumed these effects will cancel). The CSL xerographic color printer ‘‘Lilac’’ prints about 16,000 pages per year, providing another estimate on the demand for color printing. Probably the Ramtek printer will be in less than continuous service, with Lilac sharing the load. Assuming a modest increase in total plotting, about 10,000 pages per year is a good estimate. At $.50 per page, this will cost $5,000.

I would prefer to see the purchasing of ribbon and paper for the Ramtek printer to be handled in the same ways as paper and toner for the other printers, as well as typewriter ribbons and pencils. Specifically the purchase should be automatic as supplies are depleted and paid from an overhead budget. Please advise me how this can be arranged.