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Chapter 9 The design philosophy of Pegasus, a quantity-production computer 183

57 Not allocated

60 Jump to N if x = 0
61 Jump to N if x ¹ 0
62 Jump to N if x ³ 0
63 Jump to N if x < 0
64 Jump to N if overflow staticizor clear; clear overflow staticizor.
65 Jump to N if overflow staticizor set; clear overflow staticizor.
66 (Unit-modify) x'm = xm + 1. Jump to N if x'm ¹ 0 (mod. 8)
67 (Unit-count) x'c = xc - 1. Jump to N if x'c ¹ 0

70 Single word read to accumulator 1. 1' = s
71 Single word write from accumulator 1. s' = 1
72 Block read from main store u' = b

The notation used here is as follows:
N is the first address (the register address) in an order.
X is the accumulator specified in an order.
n is the word in N before obeying the order.
x is the word in X before obeying the order.
p and q are the words in 6 and 7 before obeying the order.
(pq) = p + 2-38q, with q > 0. This is a double-length number.
x', n', p' and q' are the corresponding values after obeying the order.
B is a block in the main store (the drum).
U is a block in the computing store.
P is the position number of a word within a block.
OVR is the overflow indicator.
xm is the modifier in X, i.e. an integer represented by the digits 1 to 13 of x.
xc is the counter in X, i.e. an integer represented by the digits 14 to 38 of x.

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