Hacker’s Delight, Second Edition

Appendix A. Arithmetic Tables for A 4-Bit Machine

In the tables in Appendix A, underlining denotes signed overflow. For example, in Table A–1, 7 + 1 = 8, which is not representable as a signed integer on a 4-bit machine, so signed overflow occurred.

TABLE A–1. ADDITION

The table for subtraction (Table A–2) assumes that the carry bit for a − b is set as it would be for , so that carry is equivalent to “not borrow.”

TABLE A–2. SUBTRACTION (ROW – COLUMN)

For multiplication (Tables A–3 and A–4), overflow means that the result cannot be expressed as ...