5
3200DX Field Programmable Gate Arrays – The System Logic Integrator Family
analogous to the wide-input AND term in a CPLD or PAL
device. The output of the D-module has a programmable
inverter for active HIGH or LOW assertion. The D-module
output is hardwired to an output pin or can be fed back into
the array to be incorporated into other logic.
Dual-Port SRAM Modules
The 3200DX dual-port SRAM modules have been optimized
for synchronous or asynchronous applications. The SRAM
modules are arranged in 256 bit blocks which can be
configured as 32 x 8 or 64 x 4 (refer to Table 1 for the number
of SRAM modules within a particular device). The SRAM
module block structure allows them to be cascaded together
to form user-definable memory spaces. Resources within the
3200DX architecture allow the SRAM modules to be
cascaded together without incurring an additional delay
penalty. A block diagram of the 3200DX dual-port SRAM
The 3200DX SRAM blocks are true dual-port structures
containing independent READ and WRITE logic. The
SRAM blocks contain six bits of read and write addressing
(RDAD[5:0] and WRAD[5:0] respectively) for 64x4 bit
blocks. When configured in byte mode, the highest order
address bits (RDAD5 and WRAD5) are not used. The read
and write ports of the SRAM blocks contain independent
clocks (RCLK and WCLK) with programmable polarities
offering active HIGH or LOW implementation. The write
and read ports of the SRAM block have eight data inputs
(WD[7:0]) and eight outputs (RD[7:0]). The SRAM block
outputs are connected to segmented vertical routing tracks.
The 3200DX dual-port SRAM blocks are ideal for
high-speed buffered applications such as DMA controllers
and FIFO and LIFO queues. Actel’s ACTgen Macro Builder
provides the capability to quickly design memory elements,
such as FIFOs, LIFOs, and RAM arrays which can be
included in any 3200DX design. Additionally, unused SRAM
blocks can be used to implement registers for other logic
within the design.
Figure 3 D-Module Implementation
7 inputs
hardwire to I/O
feedback to array
Programmable
inverter
Figure 4 Dual-Port SRAM Module
SRAM Module
32 x 8 or 64 x 4
(256 bits)
Read
Port
Logic
Write
Port
Logic
RD[7:0]
Routing Tracks
Latches
Read
Logic
[5:0]
RDAD[5:0]
LEN
REN
RCLK
Latches
WD[7:0]
Latches
WRAD[5:0]
Write
Logic
MODE
BLKEN
WEN
WCLK
[5:0]
[7:0]