Patent GB-954801-A (GB)
Title: Digital electric computers
IPC: G06F3/00
Filed: 1960-08-24
Abstract: 954,801. Editing data. INTERNATIONAL BUSINESS MACHINES CORPORATION. Aug. 24, 1960 [Sept. 8, 1959], No. 29204/60. Heading G4A. Data is edited by merging the data word with a control word containing the characters required. The apparatus is incorporated in the machine of Specification 954,802 which operates in words of varying length. The address of an edit instruction is taken from instruction register 29, incremented in modifier 35 and returned to register 29. The address specifies the vertical column in core storage 11 containing the first (least significant) character of the word. The edit word contains the address of the data word which is set up in A memory address register (AMAR) 33, and of the edit control word set up in BMAR 31. The OP section of the instruction word is sent to register 27. In an A cycle the character stored at the address in AMAR 33 is read out to B register 23 and is then read back into the same character location (A store) at the same time being transferred to A register 25. In a B cycle a character is read out to the B register and may then be written back in the position from which it was taken (B store) or be replaced by a different character. The method of editing is to transfer either the character standing in the A register or that in the B register to the B control word storage location at the end of a B cycle, with the provision that special characters, blanks for example, may be generated and stored under certain circumstances. If the character is special or is taken from the B register then a B cycle follows at once. If the character is taken from the A register an A cycle and a B cycle follows. Consider the data word 00257426 (assumed positive) and the control word #Sbbb, bb0. bb&CR&** (b = blank). The characters #S *, and . are always written in the edited word, the characters CR are suppressed if the data word is positive, the character 0 indicates the last position at which zero suppression is possible, and the character & gives a blank in the edited word. If #S appears in the body of the word, it is floating and is placed immediately before the first significant digit. If 0 is not in the control word zero suppression does not take place. The underlined character indicates an end of word mark: a scan is stopped only by the control word mark. The edit operation of the above data word by the control word given starts as follows: - A cycle: 6 to A register, 6 written in A store; B cycle: * to B register, * to B store; B cycle: * to B register, * to B store; B cycle: & to B register, blank to B store (special character written); B cycle: R to B register; blank to B store (data word positive, character suppressed); on succeeding B cycles blanks are entered in the B store until B cycle: b to B register, 6 (contents of A register) to B store; A cycle: 2 to A store, 2 to A register; B cycle: b to B register, 2 to B store; and so on until #S has been entered into B store. The character replacing the 0 in the control word (in this case 4) is marked to determine the end of the zero suppression which now begins. The presence of the 0 in the control word has set a latch which causes the address modifier to decrement BMAR 31 and the characters of the edited word now in the B store are read out in reverse order, the zeros and any punctuation being replaced by blanks until the first significant digit is sensed. Any non- punctuation character will restore zero suppression but the operation stops at the word mark (4). Other operations possible are asterisk fill in which asterisks replace blanks, decimal elimination which takes out non-significant zeros to the right of the decimal point, or sign indication. The control circuits are described (Figs. 2a to 2e not shown).