EP2AGX95EF29C6N Datasheet, PDF (56/380 Pages) Altera Corporation – Device Interfaces and Integration

3–8
Chapter 3: Memory Blocks in Arria II Devices
Memory Features
Mixed Width Support
M9K and M144K blocks support mixed data widths inherently. MLABs can support
mixed data widths through emulation with the Quartus II software. When using
simple dual-port, true dual-port, or FIFO modes, mixed width support allows you to
read and write different data widths to a memory block. For more information about
the different widths supported per memory mode, refer to “Memory Modes” on
page 3–10.
1 MLABs do not support mixed-width FIFO mode.
Asynchronous Clear
Arria II memory blocks support asynchronous clears on the output latches and output
registers. Therefore, if your RAM is not using output registers, you can still clear the
RAM outputs using the output latch asynchronous clear. Figure 3–7 shows a
functional waveform showing this functionality.
Figure 3–7. Output Latch Asynchronous Clear Waveform
outclk
aclr
aclr at latch
q
You can selectively enable asynchronous clears per logical memory using the RAM
MegaWizard Plug-In Manager.
f For more information about the RAM MegaWizard Plug-In Manager, refer to the
Internal Memory (RAM and ROM) Megafunction User Guide.
Error Correction Code Support
Arria II GZ M144K blocks have built-in support for ECC when in ×64-wide simple
dual-port mode. ECC allows you to detect and correct data errors in the memory
array. The M144K blocks have a single-error-correction double-error-detection
(SECDED) implementation. SECDED can detect and fix a single bit error in a 64-bit
word, or detect two bit errors in a 64-bit word. It cannot detect three or more errors.
The M144K ECC status is communicated using a three-bit status flag
(eccstatus[2..0]). The status flag can be either registered or unregistered. When
registered, it uses the same clock and asynchronous clear signals as the output
registers. When unregistered, it cannot be asynchronously cleared.
Arria II Device Handbook Volume 1: Device Interfaces and Integration
December 2011 Altera Corporation