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8 bits vs. 9 bits in RAM Blocks

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Guest

Fri Jun 29, 2018 9:45 pm   



The Xilinx, Altera/Intel and the mainline Lattice devices all support RAM blocks in widths of multiples of 9 bits. Some other devices only have RAM widths of multiples of 8 bits or less.

Does this make much of a difference to you? Do you use the 9 bit widths in your designs?

Rick C.

Tobias Baumann
Guest

Sat Jun 30, 2018 2:45 am   



Am 29.06.2018 um 22:22 schrieb gnuarm.deletethisbit_at_gmail.com:
Quote:

Does this make much of a difference to you? Do you use the 9 bit widths in your designs?


Yes, 9 bit width RAM is very interesting in video processing. When you
have RGB data with 12 bit each, then you can use 4x9 bit RAM for storing
the 36 bit video data exactly, without wasting any ressources.

Sometimes the additional bit is very helpful when dealing with
"traditional" 8 bit data and needed an additional parity bit.

--
Viele Grüße,
Tobi

https://www.elpra.de

Michael Kellett
Guest

Mon Jul 02, 2018 9:45 am   



On 29/06/2018 21:22, gnuarm.deletethisbit_at_gmail.com wrote:
Quote:
The Xilinx, Altera/Intel and the mainline Lattice devices all support RAM blocks in widths of multiples of 9 bits. Some other devices only have RAM widths of multiples of 8 bits or less.

Does this make much of a difference to you? Do you use the 9 bit widths in your designs?

Rick C.

I've made use of the extra bits for meta data:


For example, in a complicated buffering system for gigabit Ethernet I
move data around the chip as 32 bit words stored in 36 bit wide
registers (4 x9). The extra 4 bits are used to say if this is the last
32 bit word in a message, how many bytes in the word are valid (always
all 4 unless its the last word), and the last bit can invalidate the
whole message.
I'd miss the extra bits if they weren't available.

MK


Guest

Wed Jul 04, 2018 11:45 am   



On Friday, June 29, 2018 at 11:22:52 PM UTC+3, gnuarm.del...@gmail.com wrote:
Quote:
The Xilinx, Altera/Intel and the mainline Lattice devices all support RAM blocks in widths of multiples of 9 bits. Some other devices only have RAM widths of multiples of 8 bits or less.

Does this make much of a difference to you? Do you use the 9 bit widths in your designs?

Rick C.


FYI, the only Altera series from "recommended for new designs" list that have RAM blocks in multiples of 9 bits are "CPLD-replacement" MAX10 and decade-old Cyclone10LP.
Cyclone5, Arria5, Stratix5, Arria10/Cyclone10GX and Stratix10 all has embedded RAM blocks in multiples of 10 bits.


Guest

Wed Jul 04, 2018 5:45 pm   



On Wednesday, July 4, 2018 at 5:45:22 AM UTC-4, already...@yahoo.com wrote:
Quote:
On Friday, June 29, 2018 at 11:22:52 PM UTC+3, gnuarm.del...@gmail.com wrote:
The Xilinx, Altera/Intel and the mainline Lattice devices all support RAM blocks in widths of multiples of 9 bits. Some other devices only have RAM widths of multiples of 8 bits or less.

Does this make much of a difference to you? Do you use the 9 bit widths in your designs?

Rick C.

FYI, the only Altera series from "recommended for new designs" list that have RAM blocks in multiples of 9 bits are "CPLD-replacement" MAX10 and decade-old Cyclone10LP.
Cyclone5, Arria5, Stratix5, Arria10/Cyclone10GX and Stratix10 all has embedded RAM blocks in multiples of 10 bits.


I didn't know that. Hmmm... that could be very useful.

Rick C.

Tomas D.
Guest

Mon Jul 30, 2018 3:45 am   



I've always found 9bits useful, especially when doing just general buffering
while waiting for memory to free up. Then put 8 bits of data and a start
signal to keep everything in sync all the time.

<gnuarm.deletethisbit_at_gmail.com> wrote in message
news:82abdd48-6290-4799-8a3c-aa62845d7e95_at_googlegroups.com...
Quote:
The Xilinx, Altera/Intel and the mainline Lattice devices all support RAM
blocks in widths of multiples of 9 bits. Some other devices only have RAM
widths of multiples of 8 bits or less.

Does this make much of a difference to you? Do you use the 9 bit widths
in your designs?

Rick C.


elektroda.net NewsGroups Forum Index - FPGA - 8 bits vs. 9 bits in RAM Blocks

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