492
Conversion Instructions Section 3-12
Description NEG(160) calculates the 2’s complement of S and writes the result to R. The
2’s complement calculation basically reverses the status of the bits in S and
adds 1.
Note This operation (reversing the status of the bits and adding 1) is equivalent to
subtracting the content of S from 0000.
Flags
Note The result for 8000 hex will be 8000 hex.
Example When CIO 000000 is ON in the following example, NEG(160) calculates the
2’s complement of the content of D00100 and writes the result to D00200.
Indirect DM/EM
addresses in BCD
*D00000 to *D32767
*E00000 to *E32767
*En_00000 to *En_32767
(n = 0 to C)
Constants #0000 to #FFFF
(binary)
---
Data Registers DR0 to DR15
Index Registers ---
Indirect addressing
using Index Registers
,IR0 to ,IR15
–2048 to +2047 ,IR0 to –2048 to +2047 ,IR15
DR0 to DR15, IR0 to IR15
,IR0+(++) to ,IR15+(++)
,–(– –)IR0 to, –(– –)IR15
Area S R
(S) (R)
2's complement
(Complement + 1)
Name Label Operation
Error Flag ER OFF
Equals Flag = ON if the result is 0000.
OFF in all other cases.
Negative Flag N ON if bit 15 of the result is ON.
OFF in all other cases.
−)
Add 1
Actual
calculation
Equivalent
subtraction
Reverse bit status
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