ABC An ABC Operator's Manual:3. Equipment and Controls

The diagram and tables below summarize the equipment, controls and indicators of the ABC of concern to the operator. Figure 3.1 presents an idealized view of the machine, for a more complete and technically concise diagram see the ABC Architecture section. In addition to a description of each item, the tables indicate for which of the three operations performed by the ABC (base-10 to base-2 conversion, pair-combination, base-2 to base-10 conversion) the item is used.

Figure 3.1: Operator's View of the ABC

Item 10to2 PR-CB 2to10 Description Table 3.1: Numbers and Cards base-10 numbers * * Coefficients in base-10 form are signed, 15 digits, limited to the range -562,949,953,421,312 to +562,949,953,421,311. base-2 numbers * * * Coefficients in base-2 form are 50-bit two's-complement integers. base-10 cards * Standard 80-column IBM cards which can hold up to 5=80/(15+1) coefficients. Thus up to 6=30/5 cards may be required per equation. base-2 cards * * * Capable of holding 30 coefficients each, and so can hold one equation. Output 10 Conversion Card * A base-10 card punched with fifteen 1's in the digits of the first coefficient. See comment for the Base-10 Card Reader.

Item 10to2 PR-CB 2to10 Description Table 3.2: Equipment Base-10 Card Reader * * For reading base-10 cards. During a 2to10 conversion operation, while the CA is actually the source of the coefficient of interest, the Output 10 Conversion Card must be present in the base-10 reader. Base-10 Display * Displays one base-10 number (unsigned). Base-2 Card Reader * * For reading base-2 cards. Base-2 Card Punch * * For punching base-2 cards. CA Memory Drum * * * Counter Abacus. Holds the coefficients of one equation. Main register for most operations. KA Memory Drum * Keyboard Abacus. Holds the coefficients of one equation. The second operand, or subtrahend for pair-combining.