I n t e g r a t o r S e r i e s F PG A s : 1 2 0 0 X L a n d 3 2 0 0 D X F a m i l i e s
3200DX devices contain a third type of logic module,
D-modules, which are arranged around the periphery of the
device. D-modules contain wide-decode circuitry which
provides a fast, wide-input AND function similar to that
found in product term architectures (Figure
3).
The
D-module allows 3200DX devices to perform wide-decode
functions at speeds comparable CPLDs and PAL devices.
The output of the D-module has a programmable inverter
for active HIGH or LOW assertion. The D-module output is
hard-wired to an output pin or can be fed back into the
array to be incorporated into other logic.
Dual-Port SRAM Modules
modules can be cascaded together to form memory spaces
of user-definable width and depth. A block diagram of the
3200DX dual-port SRAM block is shown in
7 Inputs
Hard-Wire to I/O
Programmable
Inverter
Several 3200DX devices contain dual-port SRAM modules
that have been optimized for synchronous or asynchronous
applications. The SRAM modules are arranged in 256-bit
blocks which can be configured as 32x8 or 64x4 (refer to
for the
number of SRAM blocks within a particular device). SRAM
Feedback to Array
Figure 3 •
D-Module Implementation
WD[7:0]
Latches
[7:0]
[5:0]
Write
Port
Logic
SRAM Module
32 x 8 or 64 x 4
(256 Bits)
Read
Port
Logic
Latches
RDAD[5:0]
WRAD[5:0]
Latches
[5:0]
Read
Logic
REN
RCLK
MODE
BLKEN
WEN
WCLK
Write
Logic
RD[7:0]
Routing Tracks
Figure 4 •
3200DX Dual-Port SRAM Block
The 3200DX SRAM modules are true dual-port structures
containing independent READ and WRITE ports. Each
SRAM module contains 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 block contain independent
clocks (RCLK and WCLK) with programmable polarities
offering active HIGH or LOW implementation. The SRAM
block contains eight data inputs (WD[7:0]) and eight
outputs (RD[7:0]) which are connected to segmented
vertical routing tracks.
The 3200DX dual-port SRAM blocks provide an optimal
solution for high-speed buffered applications requiring fast
FIFO and LIFO queues. Actel’s ACTgen Macro Builder
provides the capability to quickly design memory functions,
Discontinued – v3.0
7
ACTEL [ Actel Corporation ]
