New microdrive internal replacement

[Popopo]

The word interpreter as it refers to software and the word interpret as it refers to your example of what you think an FPGA does, are not the same. There were Z80 processors made in Russia that were not made from original spec so they "interpreted" how the chip should function, but that is considered real hardware. Point-of-view is a slippery slope here. I think FPGA's fit into the real of hardware, whereas emulators are software...it's a pretty clear delineation. Now you can replace some hardware with software (i.e. PiStorm) but that's just faster software emulating the real hardware.

Ah! so FPGAs not use software? really?
So a bitstream is not software, and the SRAM where is storage is not RAM memory... ah...
If you talk about CPLD down... still we could give a gap for discuss it.
It is what it is. We can paint it as we want to suits our arguments.

[Popopo]

Well, the sampled Microdrive sound used can be found in the source code: https://github.com/stephen-usher/vDrive ... snd-v1.ino

I need to implement your solution. I bought the same thing that Noel did and its scraping microdrive sound was pretty bad so I uninstalled it. I really liked your solution.

If I'm not wrong (too much) Noel commented it and improved it in another of his videos.
Whatever... Really that is necessary when there is a full processor unit with analog and digital outputs?

[Popopo]

You don't really need a PCB. My first version was a bit of vero board, a 14 pin socket and some bodge wires.


IMG_1938.jpg

Oh pretty nice and simple solution.
I like it.

[Popopo]

The Pi Pico probably has enough horsepower to provide that sound directly in response to a request to 'run' the Microdrive motor, and requires only a single pin - connect a resistor to this pin and join it to the resistor that feeds the base of the transistor driving the speaker (I believe this components is close the Microdrives on the QL motherboard)

TR1 is the transistor, R95 is the 1K resistor between +5V and the base of the transistor and this connection comes from Pin 22 of the IPC (large chip near the microdrives)

A similar value resistor connected to this pin from the Pi Pico sound output pin (yet to be determined) could provide sufficient drive to make some sound for you on the QL speaker.

Sounds good.
Very productive pool of ideas to improve this project.

[Peter]

So a bitstream is not software, and the SRAM where is storage is not RAM memory... ah...

The Q68 has a flash-based "instant on" FPGA for example. An FPGA is just a logic device.
The logic is programmable, but it consists of gates, flipflops and wires just as an ASIC.
The design process includes placing logic on a chip and routing wires, it is definitely hardware development, not software development.

[bwinkel67]

...and as Peter alluded to, emulators are really nothing more than fancy interpreters. I've written both...not only the ZXSimulator which is a ROM emulator (i.e. that is really an interpreter that mimics the interpreter of the original ZX81) but also true processor-based emulators. They all take the same approach...a huge switch statement where you parse the arguments, set some global flags, and move on to the next instruction. It has a very human readable flow. Compare that, say to an 8-bit full adder circuit using gates, that is quite a bit different, and even though it has its own flow, is not as easily relatable to algorithmic logic of a program. I teach both and see students either take to one or the other. The good ones can take to both, but it is in stark difference to each other.

[Popopo]

So a bitstream is not software, and the SRAM where is storage is not RAM memory... ah...

The Q68 has a flash-based "instant on" FPGA for example. An FPGA is just a logic device.
The logic is programmable, but it consists of gates, flipflops and wires just as an ASIC.
The design process includes placing logic on a chip and routing wires, it is definitely hardware development, not software development.

So software is not logic and is not programmable? Working over flipflops, wires and gates? the computering world never understood that software runs over Eter.
Ohh yes... remover this SRAM from your FPGA and boot it up XD I will see a beautiful nothing happen.

Again... you can paint it as you want, but FPGA is itself a Von Neumann architecture.
I don't know about Q68, and it doesn't matter if is implemented over an FPGA, a set of logic ICs and passive components... whatever. Without a software (bitstream)... that is nothing. Not even a set of gates defined.

Annnd it is OK if you love FPGAs, I do too! but a FPGA used for replacement of a logic gotten by inverse engineering is a emulation even if you repeat the same 100000000000 times.

[Popopo]

...and as Peter alluded to, emulators are really nothing more than fancy interpreters. I've written both...not only the ZXSimulator which is a ROM emulator (i.e. that is really an interpreter that mimics the interpreter of the original ZX81) but also true processor-based emulators. They all take the same approach...a huge switch statement where you parse the arguments, set some global flags, and move on to the next instruction. It has a very human readable flow. Compare that, say to an 8-bit full adder circuit using gates, that is quite a bit different, and even though it has its own flow, is not as easily relatable to algorithmic logic of a program. I teach both and see students either take to one or the other. The good ones can take to both, but it is in stark difference to each other.

So mimic... that implies that is not the same.
If not the same ... approach of real one.
If it is a approach because it is not the same... is a emulation.
I'd also tought them.

From the LAB ... FPGAs need a configuration to run, that configurations is a software or bitstream to set it up in a way programmed (nowadays they even can be programmed using C) or by visual or xHDL or Verilog... whatever...
Same than another software running over a more general machine. That's it.
FPGA are usually faster, that's all. But faster now doesn't mean tomorrow. We could even compare a FPGA from 30 years ago with a fast general ARM computer of nowadays to see the gap.
FPGA usually... have a specific purpose (set by software or bitstream), general computers (micro or whatever) are not so specific.

PLease... why not to open another thread about this conversation? I love it, but...
We are in a lack of respect to Dr. Gusman who opened it and I don't think for our personal POV about FPGAs...
Please, let's re/move all this messages to another specific thread. Already I feel sorry and it's not polite. It is going too far. Let's enjoy our POVs in a better place.
admins, please
Please, move all our messages about FPGAs to another thread.

[Derek_Stewart]

Hi,

Looks great.

Can the cartridges work with the LCD screen and LEDs and use the QL MDV LEDs ?

[Peter]

Annnd it is OK if you love FPGAs, I do too!

Actually I'd much prefer NXP still producing up to date 68K CPUs on fixed silicon.
FPGAs are just a workaround, as they allow to implement an affordable, true 68K CPU without emulation.