Idea: Online Interface A simulator

[evank]

I had an idea this morning, inspired by the work of @amine who is configuring some of the Lego 8-bit software to work in Archive.org online emulators.

My idea is that someone should make an online Interface A emulator (I don't possess anywhere near the technical skills to do this.)

As I imagine it, you'd go to a website (I'm happy to host it via my own site, www.brickhacks.com) and you would see a virtual Interface A. You'd also see a selection of virtual 4.5V peripherals (optical sensors, touch sensors, motors, lights). You would select which computer you want to use, and based on that decision you'd select your programming environments (Lines, LOGO, BASIC, assembly, and so on.) Then you could connect peripherals to the desired Interface A ports and program it as you like. You'd also be able to activate the sensors, so that your program responds accordingly.

The system should be fully usable just by going to the appropriate website, and ideally made with open-source techology. I don't want anyone to have to download, install anything, compile, or whatever.

Is there anyone with the interest, skills, and time to build this?

I'm cross-posting this idea to the Interface A group on Facebook.

[ludov]

I love retro computing and have made some simple emulators for work in the past, but this seems a big undertaking. I admit not knowing anything about interface A, so quick a primer would help in assessing the feasibility of such a project. 
In any case, how do you envision “closing the loop”, making sensors react to things moved by motors?

[Toastie]

35 minutes ago, ludov said:

In any case, how do you envision “closing the loop”, making sensors react to things moved by motors?

That is what I also have been thinking about - with no links between actuator and sensor, I would not know to. However, for straight forward programming, having the 6 virtual output LEDs on a virtual 9750 box come on and off may be sufficient? For the 2 inputs, either pressing an assigned key would toggle them from open to closed, or some predefined pulses at rates <200 Hz (9750 inputs can hardly handle higher on/off frequencies, as their hardware is the limiting reason). Here is my virtual 9750 box (second picture, the first is a TCLogo screenshot) - it is a QBasic program running in DOSBox-X in “simulation” mode. I can switch to serial and parallel I/O, but then the hardware must be attached:

It is a follow-up post in a long thread illustrating 9750 operation with modern computers. The entire thread is meant to be a reference for programming 9750.

Best
Thorsten 

   

[amine]

https://lgauge.com/technic/LEGOInterfaceA/9750(1093).htm

 

Can we embed that code into the web browser ?

Edited January 5 by amine

[Toastie]

I have no clue - it sounds doable, at least regarding the interface layout and internal logic (LEDs on of and such).

However, this software reads and writes to real ports on a real PC. That could also be changed to TCP/IP sockets (I am wildly guessing). 

But where I am totally lost is how to let an existing (DOS etc.) emulator to emit TCP/IP data? Wouldn't that require recompiling the emulator with changes made to its source code? Or are the emulators, that can be configured that way? I looked into the DOSBox-X config file, but did not find anything.

But: Others certainly know more!!! Just trying to keep this topic above water.

Best
Thorsten   

[amine]

21 hours ago, Toastie said:

I have no clue - it sounds doable, at least regarding the interface layout and internal logic (LEDs on of and such).

However, this software reads and writes to real ports on a real PC. That could also be changed to TCP/IP sockets (I am wildly guessing). 

But where I am totally lost is how to let an existing (DOS etc.) emulator to emit TCP/IP data? Wouldn't that require recompiling the emulator with changes made to its source code? Or are the emulators, that can be configured that way? I looked into the DOSBox-X config file, but did not find anything.

But: Others certainly know more!!! Just trying to keep this topic above water.

Best
Thorsten   

And with a qbasic program ?

 

[Toastie]

On 1/7/2026 at 8:14 PM, amine said:

And with a qbasic program ?

Same thing, I'm afraid ...

However, as posted in the Control Lab thread, these two emulators are running in a browser and have DOSBox-X as their base, that is what I understood. DOSBox-X is much more accurate than DOSBOX, regarding hardware simulation/access. I am using DOSBox-X for years now. It is also currently under active development.

Maybe this could be a first move in the direction of @evank's proposal? It would then still access real hardware on the machine running the browser, but when that is doable, possibly the other side, the virtual 9750 is doable as well?

Again, I have no clue how to do that, nor have I used the browser emulators.

Best
Thorsten