
Lucent Technologies Inc.
35
Data Sheet
June 1999
ORCA Series 2 FPGAs
Interquad Routing
 (continued)
5-4201(F).r4
Figure 31. Horizontal Subquad Routing 
Connectivity
The X4 and XH lines make the only connections to the 
subquad lines; therefore, the array remains symmetri-
cal and homogeneous. Since each subquad is made 
from a 4 x 4 array of PLCs, the distance between sets 
of subquad lines is four PLCs, which is also the dis-
tance between the breaks of the X4 lines. Therefore, 
each X4 line will cross exactly one set of subquad lines. 
Since all X4 lines make the same connections to the 
subquad lines that they cross, all X4 lines in the array 
have the same connectivity, and the symmetry of the 
routing is preserved. Since all XH lines cross the same 
number of subquad blocks, the symmetry is maintained 
for the XH lines as well.
The new subquad lines travel a length of eight PLCs 
(seven PLCs on the outside edge) before they are bro-
ken. Unlike other inter-PLC lines, they cannot be con-
nected end-to-end. As shown in Figure 30, some of the 
horizontal (vertical) subquad lines have connectivity to 
the subquad to the left of (above) the current subquad, 
while others have connectivity to the subquad to the 
right (below). This allows connections to/from the cur-
rent subquad from/to the PLCs in all subquads that sur-
round it.
Between all subquads, including in the center of the 
array, there are three groups of subquad lines where 
each group contains four lines. Figure 31 shows the 
connectivity of these three groups of subquad lines 
(HSUB) to the VX4 and VXH lines running between a 
vertical pair of PLCs. Between each vertical pair of 
subquad blocks, four of the blocks shown in Figure 31 
are used, one for each pair of vertical PLCs. 
The first two groups, depicted as A and B, have con-
nectivity to only one of the two sets of X4 lines between 
pairs of PLCs. Since they are very lightly loaded, they 
are very fast. The third group, C, connects to both 
groups of X4 lines between pairs of PLCs, as well as all 
of the XH lines between pairs of PLCs, providing high 
flexibility. The connectivity for the vertical subquad rout-
ing (Vsub) is the same as described above for the hori-
zontal subquad routing, when rotated onto the other 
axis.
At the center row and column of each quadrant, a 
fourth group of subquad lines has been added. These 
subquad lines only have connectivity to the XH lines. 
The XH lines are also broken at this point, which 
means that each XH line travels one-half of the quad-
rant (i.e., one-quarter of the device) before it is broken 
by a CIP Since the XH lines can be connected end-to-
end, the resulting line can be either one-quarter, one-
half, three-quarters, or the entire length of the array. 
The connectivity of the XH lines and this fourth group of 
subquad lines, indicated as D, are detailed in Figure 
32. Again, the connectivity for the vertical subquad 
routing (VSUB) is the same as the horizontal subquad 
routing, when rotated onto the other axis.
5-4202(F).r3
Figure 32. Horizontal Subquad Routing 
Connectivity (Half Quad)
A
C
B
HSUB[11]
HSUB[10]
HSUB[9]
HSUB[8]
HSUB[7]
HSUB[6]
HSUB[5]
HSUB[4]
HSUB[3]
HSUB[2]
HSUB[1]
HSUB[0]
HSUB[11]
HSUB[10]
HSUB[9]
HSUB[8]
HSUB[7]
HSUB[6]
HSUB[5]
HSUB[4]
HSUB[3]
HSUB[2]
HSUB[1]
HSUB[0]
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
A
D
B
HSUB[11]
HSUB[10]
HSUB[9]
HSUB[8]
HSUB[15]
HSUB[14]
HSUB[13]
HSUB[12]
HSUB[3]
HSUB[2]
HSUB[1]
HSUB[0]
HSUB[11]
HSUB[10]
HSUB[9]
HSUB[8]
HSUB[15]
HSUB[14]
HSUB[13]
HSUB[12]
HSUB[3]
HSUB[2]
HSUB[1]
HSUB[0]
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
C
HSUB[7]
HSUB[6]
HSUB[5]
HSUB[4]
HSUB[7]
HSUB[6]
HSUB[5]
HSUB[4]