Pat4910655

United States Patent 115 Ashkin et al. {11] Patent Number: 4,910,655 [45] Date of Patent: Mar. 20, 1990 [54] (75] (73] [21] (22] (51) [52] [58] [56] APPARATUS FOR TRANSFERRING SIGNALS AND DATA UNDER THE CONTROL OF A HOST COMPUTER Inventors: Peter B. Ashkin, Los Gatos; Michael Clark, Glendale, both of Calif. Assignee: Apple Computer, Inc., Cupertino, Calif. Appl. No.: 765,396 Filed: Ang. 14, 1985 Int. CL.*+ GO6F 13/42; GO6F 13/14 WS. CD. eeeccctesestsesserseeneeseeenes 364/200; 364/222.2; 364/242. 64/260.1; 364/261.2; 364/284.3; 371/57.2; 340/825.07; 340/825.52 Field of Search ... 364/200 MS File, 900 MS File, 364/514; 371/22, 57; 340/825.50, 825.52, 825.51, 825.53, 825.07, 825.06; 370/85, 94; 375/55 References Cited U.S. PATENT DOCUMENTS 3,221,307 11/1965 Manning . 364/200 360/40 . 364/200 370/67 - 364/200 375/55 3,646,534 2/1972 Miller 3,715,725 2/1973 Kievit . 3,787,627 1/1974 Abramson et 3,836,888 9/1974 Boenke et al. .. 3,863,025 1/1975 Gonsewski et al. 3,979,723 9/1976 Hughes et al. . 4,063,220 12/1977 Metcalfe et al. 340/825.5 4,071,908 1/1978 Brophy et al. . 364/900 4,345,250 8/1982 Jacobsthal 371/57 4,360,870 11/1982 McVey 4,373,181 2/1983 Chisholm . 364/900 - 340/825.52 - 364/200 - 340/825.08 4,628,478 12/1986 Henderson, Jr. ...... 4,638,313 1/1987 Sherwood, Jr. et al. 4,660,141 4/1987 4,667,193 5/1987 4,675,813 6/1987 364/200 4,677,613 6/1987 . 370/85 4,701,878 10/1987 Gunket et al. . 364/900 4,710,893 12/1987 McCutchean et al. 364/900 4,716,410 12/1987 Nozaki .... 340/825.52 4,760,553 7/1988 Buckley et al 4,773,005 9/1988 Sullivan .. 4,775,931 10/1988 Dickie et al. FOREIGN PATENT DOCUMENTS 0051425 8/1982 European Pat. Off. . 0104545 4/1984 European Pat. Off. . 59-52331 3/1984 Japan . 1508854 4/1978 United Kingdom . 1518565 7/1978 United Kingdom . 2035636 6/1980 United Kingdom . 2070826 5/1984 United Kingdom . OTHER PUBLICATIONS Hill et al, “Dynamic Device Address Assignment Mechanism”, IBM Technical Disclosure Bulletin, vol. 23, No. 8, Jan. 1981, pp. 3564-3565. Primary Examiner—Thomas C. Lee Attorney, Agent, or Firm—Blakely, Sokoloff, Taylor & Zafman [57] ABSTRACT A communications medium for transmitting data be- tween a plurality of peripheral devices and a host com- puter. Only one device may talk on the bus at a time and only in response to a command from the host. When a peripheral device needs to be serviced, it sends out a 4,442,502 4/1984 Friend et al. 364/900 4,498,169 2/1985 Rozmus .... 340/825.5 service request signal by holding the bus low after any 4,562,535 12/1985 Vincent et al . 364/200 command signal. The device continues to request ser- 4,568,930 2/1986 Livingston et al. 340/825.52 vice until it receives a talk command from the host 4,570,220 2/1986 Tetrick et al. . 364/200 computer. When more than one device are the same 5ge.063 ¥ 1986 Shah et al. 364/200 type (for example, two mice) are coupled to the bus, the Weer eio8e pang ot a i 330/875 08 host computer assigns new addresses to the d…