1992-11-16
1995-11-14
Bayerl, Raymond J.
395112, 395115, 395116, G06K 1500
Patent
active
054674352
ABSTRACT:
A host computer and printer and method of operation wherein the printer is able to switch between two modes of operation. When the printer is powered up, it initializes its internal data registers and printer memory, followed by a check to see if additional firmware, in the form of a cartridge or the like, is added to the printer. If additional firmware is present, the printer turns operational command over to the additional firmware. The present invention, residing in the additional firmware, stores a complete image of the printer state, internal registers, and memory in a location that cannot be accessed by either mode of operation. The present invention compresses the data so that the complete image of the printer state, internal registers, and memory occupies approximately eight KBytes of memory. The storage location may be part of the printer memory itself, or any other suitable location. The additional firmware then returns operational control to the original firmware within the printer thus allowing the printer to operate in the first mode of operation. The host computer may cause the printer to switch to the second mode of operation by simply overwriting the internal data registers and printer memory, except for the portion of printer memory that is used to store the compressed image of the initial printer state. The printer may be switched back to the first mode of operation by expanding the compressed image to restore the printer to its initial state. From the perspective of the printer, it has just completed initialization. Thus, the printer may be easily and quickly switched modes of operation.
REFERENCES:
patent: 4353653 (1982-10-01), Zimmerman
patent: 4881180 (1989-11-01), Nishiyama
patent: 5075841 (1991-12-01), Kaneko
patent: 5084831 (1992-01-01), Morikawa et al.
patent: 5108208 (1992-04-01), Gardner
patent: 5113355 (1992-05-01), Nomura
patent: 5220674 (1993-05-01), Morgan et al.
M. Hamdi, "Design Methodology of Multi Processor Systems for Real-Time Applications," International Journal of Mini & Microcomputers, 14/2:77-81, 1992.
Dennis Stephen V.
Douglas George H.
McCormick William B.
Bayerl Raymond J.
Legree Tracy M.
Microsoft Corporation
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