Patent GB-886954-A (GB)
Title: Improvements in or relating to input/output equipment for electric digital computers
IPC: G06F9/00
Filed: 1960-08-17
Abstract: 886,954. Electric digital-data-storage apparatus. SOC. D'ELECTRONIQUE ET D'AUTOMATISME. Aug. 17, 1960 [Aug. 21, 1959], No. 28525/60. Class 106 (1). Apparatus for transferring data between a magnetic drum and a magnetic tape comprises in the input to the magnetic drum a first counter stepped each time a complete word is read from the magnetic tape and means for recording on the drum said word and a numerical code from said counter, and in the input to the magnetic tape a second counter stepped each time a complete word is read from the drum and a comparator comparing the total in the counter with identifying digits of the sensed words, means being provided when equality is attained for recording the associated word. As described each word on the tape comprises four characters, each character having six data bits plus a synchronization bit and a parity bit, whereas on the drum each word comprises 24 data bits plus a 5-digit " transfer address " portion, each drum track having space for 128 such words, a transfer operation being effective to transfer 32 words. Tape to drum transfer.-A "transfer " instruction causes a signal at a terminal 11 to set a bi-stable device 10, thereby activating a tape read-out device 7. Each synchronization digit read actuates a four position character counter 15 adapted to route the successive data parts of four characters composing a word to successive locations in a register 14. When four characters have been read, the counter 15 causes the contents of the register 14 to be transferred to a further register 19, a word counter 17 being stepped on by one digit. The total in the counter 17 is registered at 20 and a single digit registered at 21 thereby unblocking a gate 27 to allow the next minor cycle marking pulse to actuate a flip-flop 24, thereby unblocking a gate 29 to the selected drum head and after a short delay at 28, initiating a parallel-to-series conversion at 22 to record the word on the drum 1. The flip-flop 24 is reset at the end of each inner cycle. When the 32nd word has been recorded on the drum, the counter 17 resets the device 10 to terminate transfer. Only each fourth possible word location on the drum track is utilized, the time corresponding to the remaining locations being for the transfer operation. Drum to tape transfer.-Data read from the drum 1 is recorded on a tape by a recording device 47. The words transferred are extracted and routed to the tape in the sequence 0-31 of their transfer address portions. A " transfer " instruction causes the activation of a terminal 51, resetting a 32 state counter 42 and, after a short delay at 35, unblocking a gate 34 in the drum read-out. The words stored on the drum are read out successively into a register 53. A comparator 41 compares the transfer address portions with the value in the counter 42 and when the required address is found a gate 40 is unblocked to unblock a four step counter 44 which receives timing pulses from the tape to control the transfer of the word in the register 53 in groups of six digits to the recording device 47.