公开(公告)号：US3629848A

公开(公告)日：1971-12-21

申请号：US3629848D

申请日：1970-09-21

Applicant: IBM

Inventor： GIBSON ROBERT G ,  GREENBERG ALLAN ,  WILCOX JOHN D

IPC: B41J29/393 ,  G06K15/08 ,  G11C7/00

CPC classification number: G06K15/08 ,  B41J29/393

Abstract: An adapter for controlling the operation of chain/train printers employs the main storage of a central processing unit to store characters to be printed and an image of the chain. Two hardware address registers are provided to read out or load the contents of the two storage areas. One register is used to address the character to be printed in the print line area. The second register addresses the character properly aligned with the print position to be printed. The two characters are read out of storage sequentially via a ''''cycle steal'''' technique. Upon acceptance of a cycle steal request, the contents of the first address register is entered into the storage address register, and the proper chain character is read out into the cycle steal register and then transferred to the universal character set register. A second cycle steal is begun by presenting the contents of the second address register to the storage address register. The proper print line character is then read out into the cycle steal register. The two characters are then compared to determine if a print hammer is to be fired.