I think we need a different word here. The FPGA is not a P2, since it does not have the same etch pattern in its silicon. It is definitely closer to the metal than an emulator, though. (However, "emulator" has been used in the past to describe a micro's selfsame silicon when additional debugging pins are brought out.)
So how about behavioral congruence to describe it?
Meh, 'too much of a mouthful. I've got an idea. Let's just call it an emulator, even though we all know better.
Back when they were designing CPUs by hand, they would build a discrete logic version, usually clock speed limited among some possible limits.
Those were referred to as simulations. Emulation is a bit different context and I understand that difference, but I have a much harder time sorting out why it would not be called a simulation.
The FPGA is clock rate limited on the boards we are using, and BTW my board and Prop Plug replacements arrived today, and are incomplete in various ways; namely, the DAC circuit part of the I/O pins.
It's in the semantics because the word emulator would never be correct really however we have come to accept the term to mean something that not only "simulates" a device but strives to be like it (rather than equal or excel). Now, I have HP and TI calculator emulators on my phone which look very close to the real thing and behave like the real thing. That's the current semantics for an "emulator", it looks and behaves like the real thing (to a degree). So an emulator can be software only and look like the real thing or in this case we have physical pins and hardware we can access so it is a Hardware Emulator rather than just a simulator (software only). Since it is emulated in Logic gates and it is a prototype we can refer to it as a Hardware Emulator with a Logic gate Prototype or HELP for short. This HELP is really helpful for me to run P2 software and test it's interaction with P2 hardware. It's the HELP I need to get started with the P2.
In Altera Quartus You not need work VHDL or Verilog.
You can made al Yours work as SCH's -- That quartus compile that to FPGA configuration file.
But I doubt you can do a lot of things with only schematics. You can do some small logic gates circuit (7 segments decoder etc...) and use some comparators/adders/flops included though.
What I like to do is view my problem from a top-down approach, and create a schematic with some black boxes representing the different parts of the circuit. Then, I implement these boxes in VHDL (but I recently switched to Verilog, I like that it is more concise and straightforward)
One reason that appeal to me is that when the D-Day will come, I think that a quite reasonable amount of work/code/objects will be ready. So all the fans will have things to play with and are not going to be left to figure out how everything work alone and have a great chip that do little out of the box!
I say emulator, you simulator, let's call the whole thing off:)
When Linus Torvalds builds his Linux operating system source on his own Intel PC and runs it that is definitely Linux.
When I take a copy of his code and compile it for a totally different architecture, say ARM, and run it on my ARM board that is not an "emulation" or "simulation" of Linux it is still actual Linux. Agreed so far?
By the same reasoning, given that the PII is written in Verilog, If we synthesize that same Verilog code into an FPGA it is as much the real PII as when it is synthesized into a custom chip. Ergo not an emulation or simulation but just another instance of the real thing.
Another thing to consider is that the PII as a chip does not exist. It only exists as a design. How can we be simulating or emulating a non-existent thing?
Of course the flaw in my argument is that a lot of what we will get on the PII is not just derived from Verilog source, particularly when it comes to the I/O where analog considerations have to be catered for I'm sure. Not to mention all that hand layout that has been going on.
In my experience most people in the industry refer to this as ASIC emulation or prototyping. e.g. search google for "Altera ASIC emulation" or "Xilinx ASIC emulation"
Even for a basic digital chip there are going to be a lot of differences in how the FPGA implementation looks as compared to the real chip. e.g. clock gating might not be fully implemented, you're not going to bother putting test logic (e.g. logicvision) into the chip, your RAMs will most likely not be sized quite the same, it's likely that it won't run at speed, large designs will be spread across multiple FPGAs, and I/Os were already mentioned.
It's really cool that Parallax is giving such wide access to this. At my company it would be a struggle to even get permission to give something like this to a single customer unless there were a really compelling reason, although it has been done.
Even the term ASIC is funny if you think about it - is the Propeller really application specific?
Comments
So how about behavioral congruence to describe it?
Meh, 'too much of a mouthful. I've got an idea. Let's just call it an emulator, even though we all know better.
-Phil
m is for mulatr... pronounced emulator... but meaning something entirely different.
Those were referred to as simulations. Emulation is a bit different context and I understand that difference, but I have a much harder time sorting out why it would not be called a simulation.
The FPGA is clock rate limited on the boards we are using, and BTW my board and Prop Plug replacements arrived today, and are incomplete in various ways; namely, the DAC circuit part of the I/O pins.
Zynq!
But I doubt you can do a lot of things with only schematics. You can do some small logic gates circuit (7 segments decoder etc...) and use some comparators/adders/flops included though.
What I like to do is view my problem from a top-down approach, and create a schematic with some black boxes representing the different parts of the circuit. Then, I implement these boxes in VHDL (but I recently switched to Verilog, I like that it is more concise and straightforward)
One reason that appeal to me is that when the D-Day will come, I think that a quite reasonable amount of work/code/objects will be ready. So all the fans will have things to play with and are not going to be left to figure out how everything work alone and have a great chip that do little out of the box!
When Linus Torvalds builds his Linux operating system source on his own Intel PC and runs it that is definitely Linux.
When I take a copy of his code and compile it for a totally different architecture, say ARM, and run it on my ARM board that is not an "emulation" or "simulation" of Linux it is still actual Linux. Agreed so far?
By the same reasoning, given that the PII is written in Verilog, If we synthesize that same Verilog code into an FPGA it is as much the real PII as when it is synthesized into a custom chip. Ergo not an emulation or simulation but just another instance of the real thing.
Another thing to consider is that the PII as a chip does not exist. It only exists as a design. How can we be simulating or emulating a non-existent thing?
Of course the flaw in my argument is that a lot of what we will get on the PII is not just derived from Verilog source, particularly when it comes to the I/O where analog considerations have to be catered for I'm sure. Not to mention all that hand layout that has been going on.
Even for a basic digital chip there are going to be a lot of differences in how the FPGA implementation looks as compared to the real chip. e.g. clock gating might not be fully implemented, you're not going to bother putting test logic (e.g. logicvision) into the chip, your RAMs will most likely not be sized quite the same, it's likely that it won't run at speed, large designs will be spread across multiple FPGAs, and I/Os were already mentioned.
It's really cool that Parallax is giving such wide access to this. At my company it would be a struggle to even get permission to give something like this to a single customer unless there were a really compelling reason, although it has been done.
Even the term ASIC is funny if you think about it - is the Propeller really application specific?
-Phil