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OR4E10 Datasheet PDF : 124 Pages
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ORCA Series 4 FPGAs
Preliminary Data Sheet
December 2000
Programmable Logic Cells (continued)
In the third submode, multiplier submode, a single
PFU can affect an 8x1 bit (4x1 for half-ripple mode)
multiply and sum with a partial product (see Figure 11).
The multiplier bit is input at F5[A:C], respectively per
nibble, and the multiplicand bits are input at KZ[1],
where K7[1] is the most significant bit (MSB). KZ[0] con-
tains the partial product (or other input to be summed)
from a previous stage. If F5[A:C] is logical 1, the multi-
plicand is added to the partial product. If F5[A:C] is log-
ical 0, 0 is added to the partial product, which is the
same as passing the partial product. CIN/FCIN can
bring the carry-in from the less significant PFUs if the
multiplicand is wider than 8 bits, and COUT/FCOUT
holds any carry-out from the multiplication, which may
then be used as part of the product or routed to another
PFU in multiplier mode for multiplicand width expan-
sion.
Ripple mode’s fourth submode features equality
comparators. The functions that are explicitly available
are A ≥ B, A ≠ B, and A ≤ B, where the value for A is
input on KZ[0], and the value for B is input on KZ[1]. A
value of 1 on the carry-out signals valid argument. For
example, a carry-out equal to 1 in AB submode indi-
cates that the value on KZ[0] is greater than or equal to
the value on KZ[1]. Conversely, the functions A ≤ B,
A + B, and A > B are available using the same functions
but with a 0 output expected. For example, A > B with a
0 output indicates A ≤ B. Table 5 shows each function
and the output expected.
If larger than 8 bits, the carry-out signal can be cas-
caded using fast-carry logic to the carry-in of any adja-
cent PFU. The use of this submode could be shown
using Figure 9, except that the CIN/FCIN input for the
least significant PFU is controlled via configuration.
Table 5. Ripple Mode Equality Comparator
Functions and Outputs
Equality
Function
A≥B
A≤B
A≠B
A<B
A>B
A=B
ORCA Foundry
Submode
A≥B
A≤B
A≠B
A>B
A<B
A≠B
True, if
Carry-Out Is:
1
1
1
0
0
0
C
DQ
REGCOUT
F5[A:C]
K7[1]
K7[0]
K6[1]
K6[0]
K5[1]
K5[0]
K4[1]
K4[0]
K3[1]
K3[0]
K2[1]
K2[0]
K1[1]
K1[0]
K0[1]
K0[0]
1
00
1
00
1
00
1
00
1
00
1
00
1
00
1
00
C
+
K7
+
K6
+
K5
+
K4
+
K3
+
K2
+
K1
+
K0
DQ
DQ
DQ
DQ
DQ
DQ
DQ
DQ
COUT
F7
Q7
F6
Q6
F5
Q5
F4
Q4
F3
Q3
F2
Q2
F1
Q1
F0
Q0
Key: C = configuration data.
Note: F5[A:C] shorted together.
Figure 11. Multiplier Submode
5-5757(F)
18
Lucent Technologies Inc.
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