Altera RAM Initializer - Manual (Page 8)

1–2 Confidential—Internal Use Only Altera Corporation
RAM Initializer (ALTMEM_INIT) Megafunction User Guide May 2008
Features
The HardCopy device family does not support the initialization of a
random-access memory (RAM) during power-up. The ALTMEM_INIT
megafunction addresses this need by providing memory initialization
functions for the HardCopy Stratix and HardCopy II devices. The
megafunction also supports Stratix devices that are migratable to
HardCopy devices, and in general, other Altera devices that come with
RAM.
The ALTMEM_INIT megafunction supports multiple RAMs. You can
add logic to the output data port of the megafunction to fan out to more
than one RAM. For example, if you want to initialize multiple RAMs to
contain all zeros, you can connect the appropriate output ports of the
ALTMEM_INIT megafunction to the RAMs that you want to initialize.
1 In this document, HardCopy devices refer to the
HardCopy Stratix and HardCopy II devices; Stratix devices
refer to the Stratix IV, Stratix III, Stratix II, and Stratix devices.
The ALTMEM_INIT megafunction initializes the RAM of a HardCopy
device with the content of a read-only memory (ROM). The ROM can be
located internally within the megafunction, or externally in an on-chip or
off-chip ROM. During initialization, the megafunction reads the content
of the ROM word-by-word and writes it to the RAM. The RAM can also
be initialized without the ROM, but the content can only be set to all
zeros.
1 Unless specified otherwise, external ROM refers to both on-chip
and off-chip ROM.
Features The ALTMEM_INIT megafunction provides the following features to
implement memory initialization in HardCopy devices:
■ Support for RAM initialization using the INIT_FILE parameter
■ Support for RAM initialization from an external ROM with fixed
latency
■ Support for RAM initialization from an external ROM with variable
latency
■ Support for RAM initialization to all zeros
■ Status signal to indicate RAM initialization status
These features can be configured easily through the RAM Initializer
MegaWizard
® Plug-In Manager.
f
For more information about the INIT_FILE parameter, refer to
Chapter 3, Specifications .