IBM 610 Manual Of Operation

Also see for 610: Technical overview and introduction

28 IBM 6 10Tape CodeThe tape may be thought of as ruled off intoa rectangular grid, eight channels wide and as longas the tape. A single column of eight channels, someof which may be punched and some not, constitutesa character in tape code. More precisely, the bottomfive channels constitute a character, the sixth chan-nel contains an even count redundancy check, andthe two top channels are used for class marks. In thedictionary of tape codes, there are 31 single-columncharacters, and 9 double-column characters, calleddoublets. The first column of a doublet is always thetape character for asterisk {''') or star and is calledthe modifier. The dictionary for translating from 610language (i.e., keyboard symbol) to tape code is con-tained in the accompanying table.The two channels on paper tape available for classmarks are used to classify instructions on the programtape. The combinations of punches in these two chan-nels give four classes of instructions, as has beenpreviously described.The sixth channel on the tape is called the re-dundancy channel. This channel is useful in verify-ing that every 610 character is correctly read. Aseach row is punched, the machine counts the punchesin channels 1 through 5 and the two class channels.If the total number of punches is odd (1, 3, or 5),the machine automatically adds a sixth punch in theredundancy channel to make the total number ofpunches even. If the total count of punches in chan-nels 1 through 5 and the two class channels is even,channel 6 is left unpunched.On the tape layout (Figure 20) we have indicatedthe correspondence between the keyboard type pro-gram symbols and the tape hole code.CONTROL PANELInstructions can be directed to the computing por-tion of the machine from the keyboard, program tape,and the control panel. We have described the methodof creating a program and of causing this program tobe punched into a program tape for the processing ofsimilar sets of data immediately or at some later time.We have mentioned that the control panel is alsocapable of giving instructions to the machine. Thisis a particularly convenient control device for han-dling sub-routine sequences. Located on the controlpanel are selectors and balance test hubs capable ofmaking choices between two courses of action. Theoperator need not turn control of the 610 over tothe control panel to gain access to these devices.Figure 21 is a picture of the pluggable controlpanel. The board is pierced by a large number of holes(indicated on the figure by small circles). Behindeach of these holes, when the board is inserted in themachine, is a metal contact finger. Two of these con-tact fingers can be electrically connected by insertingthe ends of a special wire into two of the holes onthe board. This is called connecting two hubs on thecontrol panel. If these hubs are interconnected prop-erly, the computer will execute operations as required.Most of the hubs fall into two classes: source hubsand function hubs. Source hubs emit impulses. Func-tion hubs accept impulses and are connected to con-trol terminals that activate the computing part of themachine. When a control terminal receives an impulsevia a wire in the control panel, it causes the machineto perform its particular function. A function hub issimilar to an instruction key on the keyboard readyOi— fscoTj-io-orxooo lU < Z.^16 • ••8 ••• #• ••• •HI•••oc a- ai ~^ _ S:I „ q;_i-"i— I— ujaiOOo.• ••>zIMMIM••• •• • 4 4•• •• • •7\H 7SO >— CO_o _o _o oU U U (J••• Tpl«¥8• 72?t ** ^ ••• I•^ • •# ••••• ••• ••••• • ••• >- 3 c4j5 UFigure 20. Tape Layout