Embedded Memory
In addition to true dual-port memory, the M4K memory blocks support
simple dual-port and single-port RAM. Simple dual-port memory
supports a simultaneous read and write. Single-port memory supports
non-simultaneous reads and writes. Figure 2–13 shows these different
M4K RAM memory port configurations.
Figure 2–13. Simple Dual-Port & Single-Port Memory Configurations
Simple Dual-Port Memory
data[]
rdaddress[]
rden
wraddress[]
wren
q[]
inclock
inclocken
inaclr
outclock
outclocken
outaclr
Single-Port Memory (1)
data[]
address[]
wren
q[]
outclock
inclock
inclocken
inaclr
outclocken
outaclr
Note to Figure 2–13:
(1) Two single-port memory blocks can be implemented in a single M4K block as long
as each of the two independent block sizes is equal to or less than half of the M4K
block size.
The memory blocks also enable mixed-width data ports for reading and
writing to the RAM ports in dual-port RAM configuration. For example,
the memory block can be written in ×1 mode at port A and read out in ×16
mode from port B.
The Cyclone memory architecture can implement fully synchronous
RAM by registering both the input and output signals to the M4K RAM
block. All M4K memory block inputs are registered, providing
synchronous write cycles. In synchronous operation, the memory block
generates its own self-timed strobe write enable (wren) signal derived
from a global clock. In contrast, a circuit using asynchronous RAM must
generate the RAM wrensignal while ensuring its data and address
signals meet setup and hold time specifications relative to the wren
Altera Corporation
January 2007
2–19
Preliminary
ALTERA [ ALTERA CORPORATION ]
