Printer using direct memory access and refreshing

Details Printer using direct memory access and refreshing Printer using direct memory access and refreshing

1995-11-02

1999-10-05

Bost, Dwayne D.

395115, G06F 1500, B41B 1500, B41J 1500

Patent

active

059637137

ABSTRACT:
In a color printer, in order to perform a high-speed print operation and ensure a refresh operation and the like of an image memory, print images which correspond to a plurality of printheads, and are bitmapped and stored in a bitmap RAM in units of colors are consecutively read out and DMA-transferred by 16 bits at a time when a read operation is designated. After this DMA operation, the refresh operation of the bitmap RAM or access to the RAM is permitted. The printer includes the same number of latch circuits as that of printheads (e.g., four). Each latch circuit stores a data transfer start address (TOPA) and a data transfer end address (ENDA) in the bitmap RAM. With this arrangement, image data can be efficiently read out. If the capacity of the bitmap RAM is small, an upper address bit in the bitmap RAM is shifted to switch discontinuous addresses to continuous addresses on the bitmap memory side. If an optional memory is implemented, the normal addressing is restored to flexibly cope with a change in the capacity of the image memory.

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