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I'm not surprised that software engineers find these concepts difficult to understand at first -- it's a very different way of thinking, and everyone has to sta

I'm not surprised that software engineers find these concepts difficult to understand at first -- it's a very different way of thinking, and everyone has to start somewhere. But I do find it kind of odd that someone would jump straight into trying to use an HDL without already knowing what the underlying logic looks like. (My CS degree program included a bit of Verilog programming, but it only showed up after about half a semester of drawing gate diagrams, Karnaugh maps and state machines.) Does this confusion typically happen to engineers who are trying to teach themselves hardware design, or is it just an indication of a terribly-designed curriculum?

pjc50 9y ago
Bit of both, really. It's certainly a different way of thinking. But I encountered fellow students struggling with this when we were undergrads. It doesn't help that Verilog can be used as an imperative language executing statements in order, nor that it has two different types of assignment operator of which only one should be used, nor that the simulator does not enforce realistic restrictions. Nor does it help that the practical way to write Verilog/VHDL is to decide what output you want the compiler to give then work backwards to the HDL input. (I've met actual design companies that turned this into a rigid waterfall flow - full block diagram before you write a line of HDL)
lvoudour 9y ago
>Does this confusion typically happen to engineers who are trying to teach themselves hardware design, or is it just an indication of a terribly-designed curriculum? Your curriculum seems very sensible to me, you learned the basics first. After all HDLs are just describing the underlying circuit, you need to know how to design it first. The basis of most confusion in my experience is that for most people (including pure electronic engineers) their "first contact" with anything digital is through software programming which, despite the recent trend in multicores and parallel execution, is highly sequential. When you try HDL for the first time after years of programming CPUs it's natural to approach it with the same thought process. It just takes time to adapt to a new "way of thinking", nothing more. I'm sure if someone learns HDL design without prior software experience will face the same issues when he/she later decides to jump to software engineering
otakucode 9y ago
How often do people jump into javascript coding without having the faintest idea of how a CPU or anything else works? When high-level facilities are made available, there are always going to be people who go to the high-level facility without having any understanding of the actual consequences of what they are doing. I'd recommend the software folks who want to get into hardware to check out the book 'Elements of Computing Systems' and the NAND2Tetris project that its based on. Its quite easy to follow along with building your own quasi-HDL things run in a simulator (with no generative for-loop stuff, you have a clock line and you use it), then build up from there to put together a CPU, memory, develop a basic OS, implement a programming language, and eventually play a game of Tetris! All with nothing but NAND gates and the convenience of being able to 'use' those tons of gates without actually having to deal with them physically.
gluggymug 9y ago
I say "terribly-designed curriculum". Maybe engineers need to be introduced to the synthesis tools at the same time as the simulator tools. Simulating RTL is only an approximation of reality. So emphasizing RTL simulation is bad. You see it over and over though. People teach via RTL simulation. Synthesis is the main concern. Can the design be synthesised into HW and meet the constraints? Because all the combinatorial logic gets transformed into something quite different in a FPGA.

pjc50 9y ago

Bit of both, really. It's certainly a different way of thinking. But I encountered fellow students struggling with this when we were undergrads. It doesn't help that Verilog can be used as an imperative language executing statements in order, nor that it has two different types of assignment operator of which only one should be used, nor that the simulator does not enforce realistic restrictions. Nor does it help that the practical way to write Verilog/VHDL is to decide what output you want the compiler to give then work backwards to the HDL input. (I've met actual design companies that turned this into a rigid waterfall flow - full block diagram before you write a line of HDL)

lvoudour 9y ago

>Does this confusion typically happen to engineers who are trying to teach themselves hardware design, or is it just an indication of a terribly-designed curriculum? Your curriculum seems very sensible to me, you learned the basics first. After all HDLs are just describing the underlying circuit, you need to know how to design it first. The basis of most confusion in my experience is that for most people (including pure electronic engineers) their "first contact" with anything digital is through software programming which, despite the recent trend in multicores and parallel execution, is highly sequential. When you try HDL for the first time after years of programming CPUs it's natural to approach it with the same thought process. It just takes time to adapt to a new "way of thinking", nothing more. I'm sure if someone learns HDL design without prior software experience will face the same issues when he/she later decides to jump to software engineering

otakucode 9y ago

How often do people jump into javascript coding without having the faintest idea of how a CPU or anything else works? When high-level facilities are made available, there are always going to be people who go to the high-level facility without having any understanding of the actual consequences of what they are doing. I'd recommend the software folks who want to get into hardware to check out the book 'Elements of Computing Systems' and the NAND2Tetris project that its based on. Its quite easy to follow along with building your own quasi-HDL things run in a simulator (with no generative for-loop stuff, you have a clock line and you use it), then build up from there to put together a CPU, memory, develop a basic OS, implement a programming language, and eventually play a game of Tetris! All with nothing but NAND gates and the convenience of being able to 'use' those tons of gates without actually having to deal with them physically.

gluggymug 9y ago

I say "terribly-designed curriculum". Maybe engineers need to be introduced to the synthesis tools at the same time as the simulator tools. Simulating RTL is only an approximation of reality. So emphasizing RTL simulation is bad. You see it over and over though. People teach via RTL simulation. Synthesis is the main concern. Can the design be synthesised into HW and meet the constraints? Because all the combinatorial logic gets transformed into something quite different in a FPGA.