On 10/12/2021 at 4:33 AM, Ju+Te said:
I'm not experienced with FPGA at all, but it sounded to me like they could be programmed that they form some kind of PCB of some generic (TTL) parts. If I understood this correctly, the schematic already exists (as "program" for the FPGA). I might be completely wrong, so please correct me.
You are correct, and what you suggest is a good analogy. There is a circuit out there as a program to be simulated on a computer known as a FPGA.
A FPGA is a computer itself, it has computing hardware, runs a program, takes input gives output same as any computer.
At the moment, the entire experience of the X16 is 'available' in the simulator, if that is what you desire. FPGA is another simulator which can run the same simulation. The simulation can be ported to windows, linux, or FPGA as you please.
Personally, I don't see it as the same as the 'real thing' where you can hold and understand each part and with that understanding you get the best abilities to program, repair, expand, adapt the design to your desires. Just as to understand the simulator on Linux, you have to understand the software running the simulation, the operating system supporting the software, the hardware supporting the operating system, to get the most out of it. You have to learn the software and toolchain and hardware which supports the FPGA itself in order to get the most out of the simulation. It is what I consider to be an unnecessary layer of abstraction from the circuit itself.
Perhaps the simulated circuit is indeed so sprawling and verbose that economy prohibits discreet parts, however I think the circuit objectives are modest. With todays lower costs of all the parts needed to build 80's level computers, I see the actual real world as a good environment for the computer circuit to exist in discreet components.
I see putting in the effort to optimize a circuit so it can be realized in discreet parts with low chip-count as necessary for the desired experience of the end user because how can you interface with a simulation? There are the added obstacles of learning every layer of abstraction, and in the end, you'd just stick to learning one or two which most suit your goals. Learning programming on the linux machine rather than learning programming on the linux machine PLUS learning programming in the simulation so you can modify and interface to the simulated x16 better and create addons, well there is the extra layer of busy work right there.
The Pi is bad enough as you cannot solder every signal and even where people do not want to pick up an iron there are benefits and innovation from other people with that same hardware to benefit from.
Less layers of abstraction equates to less learning required for access. So I'm personally against FPGA, it's not worth learning for me, I'd sooner just design AND THEN OPTIMIZE the circuit so its easily built economically.
On 10/12/2021 at 5:06 AM, picosecond said:
Imagine a huge Ben Eater style breadboard prepopulated with thousands of simple TTL gates and flip-flops, but no wires. By itself this logic does nothing, but by adding the right wires one could implement many possible useful circuits.
Has anyone here built his video card circuit? I have not, but I think that some of the inverters can be omitted from his circuit without changing it's function or even the circuit beyond the omissions. I should try to contact him perhaps, but I'm sure he's busy, maybe someone else has built it.