MAS281 Dynex, MAS281 Datasheet - Page 18

• Manufacturer Part Number: MAS281
• Description: MIL-STD-1750A Microprocessor
• Manufacturer: Dynex

MAS281
4.2.4 IMMEDIATE LONG (IM, IMX)
Addressing; one allows indexing and one does not. For the
indexable form, if the specified index register, RX, is not equal
to zero, the contents of RX are added to the immediate field to
form the required operand; otherwise, the immediate field
contains the required operand.
4.2.5 IMMEDIATE SHORT (IS)
the 16-bit instruction. The Immediate Short addressing mode
accommodates two formats; one which interprets the contents
of the immediate field as positive data and the other which
interprets the contents of the immediate field as a negative
data.
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There are two formats which implement Immediate Long
In this mode the required 4-bit operand is contained within
Figure 9: Register Set Model
4.2.5.1 IMMEDIATE SHORT POSITIVE (ISP)
between 1 and 16.
4.2.5.2 IMMEDIATE SHORT NEGATIVE (ISN)
between -1 and -16. Its internal form is a two’s complement,
sign-extended 16-bit number.
4.2.6 INSTRUCTION COUNTER RELATIVE (ICR)
instructions. The contents of the instruction counter minus two
(the address of the current instruction) is added to the sign-
The immediate operand is treated as a positive integer
The immediate operand is treated as a negative integer
This addressing mode is used for 16-bit branch
Figure 10: Data Formats