Output Switch Matrix
The output switch matrix allows macrocells to be connected to any of several I/O cells within a
PAL block. This provides high flexibility in determining pinout and allows design changes to
occur without effecting pinout.
In MACH 4 devices with 2:1 Macrocell-I/O cell ratio, each PAL block has twice as many
macrocells as I/O cells. The MACH 4 output switch matrix allows for half of the macrocells to
drive I/O cells within a PAL block, in combinations according to Figure 9. Each I/O cell can
choose from eight macrocells; each macrocell has a choice of four I/O cells. The MACH 4 devices
with 1:1 Macrocell-I/O cell ratio allow each macrocell to drive one of eight I/O cells (Figure 9).
Each I/O cell can
choose one of 8
macrocells in
all MACH 4
devices.
M0
M1
M2
M3
M4
I/O0
M5
I/O1
M6
I/O2
M7
I/O3
M8
I/O4
M9
I/O5
M10
I/O6
M11
I/O7
M12
M13
M14
M15
Each macrocell can drive
one of 4 I/O cells in
MACH 4 devices with
2:1 macrocell-I/O cell ratio.
M0
I/O0
M1
I/O1
M2
I/O2
M3
I/O3
M4
I/O4
M5
I/O5
M6
I/O6
M7
I/O7
M8
I/O8
M9
I/O9
M10
I/O10
M11
I/O11
M12
I/O12
M13
I/O13
M14
I/O14
M15
I/O15
Each macrocell can drive
one of 8 I/O cells in
M4(LV)-32/32 devices.
Figure 9. MACH 4 Output Switch Matrix
14
MACH 4 Family