Embedded Systems Conference
Breaking News
Comments
Newest First | Oldest First | Threaded View
<<   <   Page 7 / 7
pattrsn
User Rank
Author
Re: Why not build on OpenRISC
pattrsn   8/7/2014 12:38:36 PM
If you want to learn more about the RISC-V ISA, go to riscv.org

pattrsn
User Rank
Author
Re: Why not build on OpenRISC
pattrsn   8/7/2014 12:31:58 PM
We started in 2010, when OpenCore only had a 32-bit address space, which was a fatal flaw that was later corrected. It is still missing the small code size option, which is requirement for IoT. 

And I am not sure if everyone understands the importance of the "Base+Extension" approach to instruction sets. This is a new approach to coping with software compatability of instruction sets. As we wrote in the associated technical report:



"RISC-V is aimed at SoCs, with a base that should never change given the longevity of the basic RISC ideas; a standard set of optional extensions that will evolve slowly; and unique instructions per SoC that never need to be reused."

Software compatability with controlled evolution.

(And it's really hard in 2014 to embrace an ISA that offers delayed branches:)

jeremybennett
User Rank
Author
Why not build on OpenRISC
jeremybennett   8/7/2014 12:07:07 PM
NO RATINGS
I'm not sold on the idea that we have to start from scratch to get an industry standard open ISA. As the article notes, we already have OpenRISC, which comes with an open bus standard (WishBone). The architecture is based on something well proven (DLX, of which David Patterson was half the design team), for which there is plenty of tutorial material.

It takes a long time to build all the software infrastructure around a new ISA. Surely far better to start with something like OpenRISC that has spent 15 years invested in its software.

The OpenRISC architecture doesn't tick all the author's boxes, but it is extensible, and the missing features (do we really need 128-bit addressing) could be added.

One feature that is not mentioned is multiprocessor support. Thanks to the work of Stefan Wallentowitz at TU Munich and others, this is something that OpenRISC now supports. It seems to me this ought to be a key feature of any new ISA.

The authors are two engineers for whom I have the greatest respect. I wish RISC-V well, because this team is certain to innovate, and that can only be good for the field. But as the basis of an industry standard open ISA? I wish they had built on what was already there, rather than starting again from scratch.

<<   <   Page 7 / 7


Radio
LATEST ARCHIVED BROADCAST
As data rates begin to move beyond 25 Gbps channels, new problems arise. Getting to 50 Gbps channels might not be possible with the traditional NRZ (2-level) signaling. PAM4 lets data rates double with only a small increase in channel bandwidth by sending two bits per symbol. But, it brings new measurement and analysis problems. Signal integrity sage Ransom Stephens will explain how PAM4 differs from NRZ and what to expect in design, measurement, and signal analysis.

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Like Us on Facebook
Special Video Section
The LTC®6363 is a low power, low noise, fully differential ...
Vincent Ching, applications engineer at Avago Technologies, ...
The LT®6375 is a unity-gain difference amplifier which ...
The LTC®4015 is a complete synchronous buck controller/ ...
10:35
The LTC®2983 measures a wide variety of temperature sensors ...
The LTC®3886 is a dual PolyPhase DC/DC synchronous ...
The LTC®2348-18 is an 18-bit, low noise 8-channel ...
The LT®3042 is a high performance low dropout linear ...
Chwan-Jye Foo (C.J Foo), product marketing manager for ...
The LT®3752/LT3752-1 are current mode PWM controllers ...
LED lighting is an important feature in today’s and future ...
Active balancing of series connected battery stacks exists ...
After a four-year absence, Infineon returns to Mobile World ...
A laptop’s 65-watt adapter can be made 6 times smaller and ...
An industry network should have device and data security at ...
The LTC2975 is a four-channel PMBus Power System Manager ...
In this video, a new high speed CMOS output comparator ...
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...