2–16
Chapter 2: Logic Array Blocks and Adaptive Logic Modules in Arria II Devices
Adaptive Logic Modules
Arria II Device Handbook Volume 1: Device Interfaces and Integration
December 2010
Altera Corporation
Register Chain
In addition to general routing outputs, the ALMs in any given LAB have register
chain outputs to allow registers in the same LAB to be cascaded together. The register
chain interconnect allows a LAB to use LUTs for a single combinational function and
the registers to be used for an unrelated shift register implementation. These resources
speed up connections between ALMs while saving local interconnect resources (refer
to
). The Quartus II Compiler automatically takes advantage of these
resources to improve utilization and performance.
1
For more information about register chain interconnect, refer to
.
Figure 2–14. Register Chain in an LAB
Note to
:
(1) You can use the combinational or adder logic to implement an unrelated, un-registered function.
D
Q
To general or
local routing
reg0
To general or
local routing
reg_chain_in
adder0
D
Q
To general or
local routing
reg1
To general or
local routing
adder1
D
Q
To general or
local routing
reg0
To general or
local routing
reg_chain_out
adder0
D
Q
To general or
local routing
reg1
To general or
local routing
adder1
F
r
om p
r
eviou
s
ALM
i
n
the LAB
To
n
ext ALM
i
n
the LAB
Combinational
Logic
Combinational
Logic
labclk