Abstract:
The invention relates to a unique input/output channel used in a data processing system. The channel couples a plurality of external devices and their control units to a central processing unit. The configuration of the channel is such that it allows each of the control units direct control over many of the central processing unit functions during an input/output cycle. It allows each of the control units to share the system''s main storage and central processing unit during these cycles. The design further allows for local store registers located in the central processing unit to be used as address registers for the external devices.
Abstract:
A high speed printer of the chain type in which the type characters on the chain are spaced apart a distance greater than the distance between adjacent print positions and in which the number of firing hammers is less than the number of print positions such that each hammer services several print positions. The attachment or control for the printer maintains identity of the type character in front of a print position optioned to print by modifying a type character counter in accord with scan being taken, print position and position of the firing hammers.
Abstract:
A printer attachment, which provides an interface between a CPU and a chain printer, contains a means which requests either one, two, or three cycle steals each time a character on the character chain is in line with an optioned print position, depending upon the correspondence between the chain character and the character to be printed. If the data to be contained in a print position is a blank, then only one cycle steal is required before another print position is optioned. After a character has been printed in a particular print position, only one cycle steal is then required each time that this print position is again optioned during the printing of a line.