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3–4
Chapter 3: Memory Blocks in Cyclone IV Devices
Overview
November 2011
Altera Corporation
shows how the
wren
and
byteena
signals control the RAM operations.
When a
byteena
bit is deasserted during a write cycle, the old data in the memory
appears in the corresponding data-byte output. When a
byteena
bit is asserted during
a write cycle, the corresponding data-byte output depends on the setting chosen in
the Quartus
®
II software. The setting can either be the newly written data or the old
data at that location.
1
Byte enables are only supported for True Dual-Port memory configurations when
both the PortA and PortB data widths of the individual M9K memory blocks are
multiples of 8 or 9 bits.
Packed Mode Support
Cyclone IV devices M9K memory blocks support packed mode. You can implement
two single-port memory blocks in a single block under the following conditions:
■
Each of the two independent block sizes is less than or equal to half of the M9K
block size. The maximum data width for each independent block is 18 bits wide.
■
Each of the single-port memory blocks is configured in single-clock mode. For
more information about packed mode support, refer to
and
“Single-Clock Mode” on page 3–15
.
Figure 3–1. Cyclone IV Devices byteena Functional Waveform
:
(1) For this functional waveform,
New Data
mode is selected.
inclock
w
ren
address
data
q (asynch)
an
XXXX
a0
a1
a2
a0
a1
a2
doutn
ABFF
FFCD
ABCD
ABFF
FFCD
ABCD
b
yteena
XX
10
01
11
XXXX
XX
ABCD
ABCD
FFFF
FFFF
FFFF
ABFF
FFCD
contents at a0
contents at a1
contents at a2
rden
Содержание Cyclone IV
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Страница 14: ...I 2 Section I Device Core Cyclone IV Device Handbook March 2016 Altera Corporation Volume 1...
Страница 106: ...II 2 Section II I O Interfaces Cyclone IV Device Handbook March 2016 Altera Corporation Volume 1...
Страница 164: ...III 2 Section III System Integration Cyclone IV Device Handbook March 2016 Altera Corporation Volume 1...
Страница 274: ...vi Contents Cyclone IV Device Handbook February 2015 Altera Corporation Volume 2...
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Страница 280: ...I 2 Section I Transceivers Cyclone IV Device Handbook February 2015 Altera Corporation Volume 2...
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