Cyclone II Architecture
Table 2–6 summarizes the features supported by the M4K memory.
Table 2–6. M4K Memory Features
Feature
Description
Maximum performance (1)
250 MHz
4,608
Total RAM bits per M4K block (including parity bits)
Configurations supported
4K × 1
2K × 2
1K × 4
512 × 8
512 × 9
256 × 16
256 × 18
128 × 32 (not available in true dual-port mode)
128 × 36 (not available in true dual-port mode)
Parity bits
One parity bit for each byte. The parity bit, along with
internal user logic, can implement parity checking for
error detection to ensure data integrity.
Byte enable
M4K blocks support byte writes when the write port has
a data width of 1, 2, 4, 8, 9, 16, 18, 32, or 36 bits. The
byte enables allow the input data to be masked so the
device can write to specific bytes. The unwritten bytes
retain the previous written value.
Packed mode
Two single-port memory blocks can be packed into a
single M4K block if each of the two independent block
sizes are equal to or less than half of the M4K block
size, and each of the single-port memory blocks is
configured in single-clock mode.
Address clock enable
M4K blocks support address clock enable, which is
used to hold the previous address value for as long as
the signal is enabled. This feature is useful in handling
misses in cache applications.
Memory initialization file (.mif)
When configured as RAM or ROM, you can use an
initialization file to pre-load the memory contents.
Power-up condition
Outputs cleared
Register clears
Output registers only
Same-port read-during-write
Mixed-port read-during-write
New data available at positive clock edge
Old data available at positive clock edge
Note to Table 2–6:
(1) Maximum performance information is preliminary until device characterization.
Altera Corporation
February 2007
2–29
Cyclone II Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
