HC4GX15 Datasheet, PDF (229/668 Pages) Altera Corporation – HardCopy IV Device Handbook

Chapter 3: Mapping Stratix IV Device Resources to HardCopy IV Devices
3–27
HardCopy IV Memory Blocks
f For information about using the HardCopy Device Resource Guide, refer to the
Quartus II Support for HardCopy Series Devices chapter in volume 1 of the Quartus II
Handbook.
Functionally, memory in HardCopy IV and Stratix IV devices is identical. Memory
blocks can implement various types of memory with or without parity, including true
dual-port, simple dual-port, and single-port RAM, ROM, and FIFO.
MLAB Implementation
In Stratix IV devices, MLABs are dedicated blocks and can be configured for regular
logic functions or memory functions. In HardCopy IV devices, MLAB memory blocks
are implemented using HCells. The Quartus II software maps the Stratix IV MLAB
function to the appropriate memory HCell macro that preserves memory function.
This allows you to use the HardCopy IV core fabric more efficiently, freeing up
unused HCells for ALM or DSP functions.
MLAB, M9K, and M144K Utilization
HardCopy IV MLAB, M9K, and M144K block functionality is similar to Stratix IV
memory blocks; however, you cannot pre-load HardCopy IV MLAB, M9K, and
M144K blocks with a .mif file when using them as RAM. Ensure that your Stratix IV
design does not require .mif files if the memory blocks are used as RAM. However, if
memory blocks are used as ROM, they are mask-programmed to the design’s ROM
contents.
1
You can use the ALTMEM_INIT megafunction to initialize a RAM block after
power-up for Stratix IV and HardCopy IV devices. This megafunction reads from a
ROM defined with the megafunction and writes to the RAM after power-up. This
function allows you to have initialized contents on a RAM block. Refer to the
Quartus II Help for implementation information about this function.
Unlike Stratix IV FPGAs, HardCopy IV MLAB, M9K, and M144K RAM contents are
unknown after power-up. However, like Stratix IV devices, all HardCopy IV memory
output registers power-up cleared, if used. When designing HardCopy IV memory
blocks as RAM, Altera recommends a write-before-read of the memory block to avoid
reading unknown initial power-up data conditions. If the HardCopy IV memory
block is designated as ROM, it powers up with the ROM contents.
One advantage over Stratix IV RAM blocks is that unused M9K and M144K blocks are
disconnected from the power rails and MLABs are only implemented as required by
your design. These unused resources do not contribute to overall power consumption
on HardCopy IV devices.
f For a list of supported features in HardCopy IV memory blocks, refer to the TriMatrix
Embedded Memory Blocks in HardCopy IV Devices chapter.
© January 2010 Altera Corporation
HardCopy IV Device Handbook, Volume 2