Reduced Instruction Set Computer processor. I'm not a computer person. Isn't a Raspberry Pi an RISC?
EFI advantages at this level don't have anything to do with the processor. They are various functions of the pintle injector and high pressure fuel. Let's discuss "semi-sequential". I'll bet readers would like to know what the term means.
I am a computer person. One that writes/compiles software as well as maintains my own personal linux distro.
RISC is basically a concept of how to optimize CPU instructions by making them uniform, and yes the ARM architecture (the specific instruction set) found on a Raspberry Pi is RISC based.
Pretty much all this means is that Robert is using an ARM chip instead of the 68HC12 cpu.
Why would that matter? Well, from the perspective of building a graphical interface, or interacting with other systems like disks or networks, a lot. In the case of firing an injector, not really that much because you are working through your instructions 25,000,000 times a second, and firing 4 injectors 45 times a second. That leaves plenty enough time left over to sample the mixture knob, the OAT sensor, the pressure sensor, the throttle position, the crank position, etc. A real time OS doesn't schedule or queue a task like your PC, if there is enough time to do everything that needs to be done, then there really isn't any advantage to having more time left over.
All of that said, I do think that the EM-5 is due for an update and I suspect Ross would agree with me. Having more injector channels and more cycles will allow you to add features, but it's the features and channels that make it better than the predecessor, not the CPU architecture.
I suspect that when the EM-6 is released it will be like the CPI-1 and CPI-2. The CPI-1 works just fine and they are still sold, but the CPI-2 has more features and is a newer generation. Take your pick.
In regards to EFII and SDS:
I find Ross balanced with transparent and technical information regarding both with the pros and cons, the limitations and the advantages.
Robert is running a more modern CPU, and the graphical interface is certainly nicer in the panel, but then I run into stuff like this:
"Dual 32 bit RISC processors provide modern 3D mapping of ignition and fuel functions to allow your engine to run with greater efficiency, easier starting, and more maximum power."
and
"Up to 10% increase in available horsepower."
and
"Decreased weight – no magnetos or mechanical fuel pump."
And I wonder what about the 32bit ARM architecture has anything to do with efficiency? Does a faster computer fire my injectors.... faster? I hope not! I don't buy a ford over a chevy because of what CPU is in it, I trust either will fire the injectors at the speeds the engine turns at. Features are what matter.
As for 10% increase in HP... well, if we are talking leaner mixtures or more timing, sure, but that can be done with the red knob and EI. If we are talking about 10% more just because of better atomization and fuel distribution, then I really have my doubts.
Decreased weight due to no mags or mech fuel pump? Right.... Well, I'm going to need an additional electric pump, so that's a wash, I omit mags, but then I have coils, duplex fuel valve, return fuel plumbing, pressure regulator, injectors, and CPU bricks. Notice I haven't said a word about additional batteries or alternators, which you would be wise to install.