公开(公告)号：DE2750212A1

公开(公告)日：1978-05-18

申请号：DE2750212

申请日：1977-11-10

Applicant: IBM

Inventor： DUVOCHEL HENRI PIERRE ,  KUHNE ROLAND EDOUARD ,  LAURENT BERNARD PIERRE

IPC: G06F17/16 ,  G06F7/50 ,  G06F7/509 ,  G06F7/544 ,  G06F7/52

公开(公告)号：GB1277795A

公开(公告)日：1972-06-14

申请号：GB4460069

申请日：1969-09-10

Applicant: IBM

Inventor： LEBIZAY GERALD ,  GUILLOU JOSEPH CHARLES ,  DUVOCHEL HENRI PIERRE ,  POTOCKI JEAN ZDZISLAW

IPC: G06F13/38 ,  H04L13/08

Abstract: 1277795 Digital transmission systems INTERNATIONAL BUSINESS MACHINES CORP 10 Sept 1969 [24 Sept 1968] 44600/69 Heading H4P In a system for transferring data between a store and a number of lines which operate at different speeds and in different modes (e.g. synchronous or start-stop) each line is scanned at least once during a scan cycle. The cycle is divided into a number of segments, a number of lines being scanned sequentially during each segment. The order of scan is determined by group control words GCW. A GCW controls the sequential scanning of a group of lines having the same mode and speed. Each GCW accesses a number of line control words LCW in each of which data sent to/from the corresponding line is disassembled/assembled. At the start of a scan cycle the first GCW of a segment is read from a store address determined by a group control address register GCAR. The GCW indicates which line is to be scanned and accesses the corresponding LCW. A bit or sample is passed to/from the LCW from/to the line. Counts stored in the GCW are incremented to indicate the address of the next LCW and the next line to be scanned. Another count is decremented to indicate how many more lines are to be scanned. If the latter is not zero the next line is scanned as above, but if it is zero and the GCW does not show that it is the last of the present segment the GCAR is incremented to extract the next GCW from the store and scanning of the next group of lines proceeds as above. However, if the GCW is the last of the segment a count representing idle steps in the segment (i.e. steps in not allocated to line scanning and hence available for other machine operations) is counted to zero. If the GCAR shows that there is a further segment to be scanned it is incremented and the first GCW of the next segment is read from the store for further scanning as above. On the other hand, if there is no further segment to be scanned the whole scan cycle is now repeated. When a character to be transmitted has been assembled in the LCW it is placed in a shift register at the line's transmitter. A counter is incremented each time the line is scanned, and the count is compared with a number (from the GCW) which tells how many times the line must be scanned in each bit duration. After this number of scans the shift register content is shifted one step and the counter reset. This continues until the whole character has been read out to the line. Start and Stop bits are added if required. When the register is empty the next character from the LCW is passed to it. During reception the GCW indicates after how many steps the line must be sampled (normally mid-bit), the sample being stored in a shift register and passed to the LCW. When the register is full the character is passed to another storage area in the LCW for delivery to the store.