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Good morning! Welcome back to the ValorosoIT channel, the channel dedicated to vintage computers. I'm at Varese Retrocomputing 2024 and, for the first time on the @ValorosoIT channel, we have Lorenzo Bolla, who made an invention for the Commodore 64, the Commodore SX-64 and, in the future, also for the Spectrum.
Do you want to talk to us a little about what you've accomplished?
Yes, it is a small cartridge, an object that aims to replace numerous objects that already exist on the market, but wants to concentrate everything in a single solution.
Ah, that sounds like a very interesting solution!
It is something that comes from the passion that unites us all here. That's right, we all share a passion for vintage electronics and computers. With this cartridge it is possible to emulate different hardware architectures. So I can go from simple Commodore cartridge emulation and load individual games.
Yes, the single game. So being a cartridge we are talking about CRT files, right?
In this case it loads the CRT files and launches them directly on the computer.
Okay, and this is the first feature.
Ah, it's already loaded. It's a quick, immediate thing: I change and the second one immediately loads.
Ah, super fast!
Super fast. So this one emulates a cartridge that attaches to the expansion port of the Commodore 64. Also SX-64, which you see on the screen. The SX-64 as a computer, in reality, is compatible with the Commodore 64, exactly a Commodore 64 in portable version.
Eh, transportable, translocable, I would say. In removable version.
The cartridge can also emulate floppy. Okay.
So in here I can go and turn on floppy mode and here I have all the emulations to be able to load the floppy drive.
So this now connects where? To the IEC port on the computer?
Yes, it is attached to the IEC port on the computer. It takes power from the expansion port, but then behind it it connects to the IEC port, which on the SX-64 is... here.
This is the video output connected to the second monitor.
Oh, and this is the parallel, serial port, the user port, which is used for modem emulation.
Ok, because exactly, your interface also acts as a modem.
Yes, let's see for a second then. Let's go back to the front. The two monitors do the same thing, right?
Same thing. This is just to see a little bigger, but it's how we worked at the time too. In portable mode you used its small monitor, but you also had to have very good eyesight. Then you connected a larger monitor.
Oh yes, external monitor. The SX-64 is truly a beautiful computer. I have one in my collection, but it doesn't have a keyboard. In fact, I'm taking advantage of it: for those of you who are watching this video, if you have a keyboard that you want to sell me, come forward at humane prices, if possible.
This is another application of the same cartridge, which is actually working in stand-alone mode.
Okay. And this one here is connected to this monitor.
This is connected to this monitor and, at this moment, the Pac-Man arcade game is being emulated in hardware.
Oh. So this one that's going around right now is the original Pac-Man of the bar table, right. But here it is emulated in FPGA?
There is programmable logic up here.
Exact. Let's talk a little about how this cartridge is built.
This cartridge has a large FPGA inside, programmable logic, within which it is possible to emulate practically everything, anything. It's just a matter of imagination.
The project is open source, so the wiring diagrams are available. I will also post some templates soon. Anyone who wants to contribute to expanding the range of software and hardware possibilities is free to do so.
He is very free to do so. We put the website in the description.
Ok, so check the description, because I will put the website where the diagrams will be inside, right?
Electrical diagrams and, soon, also a basic template from which to start, to make it easier for those who have never picked it up and are having to write software for the first time.
Instead, as far as functionality is concerned, when using it connected to the computer, I see that there are a number of possibilities.
Yes, yes, yes. So, the cartridge itself has 2 MB of RAM, 2 MB of flash to be able to load all the various cartridges in it. The FPGA acts as the glue and makes everything work. You can also have audio inputs/outputs, designed to go to the ZX Spectrum's cassette interface.
Oh, okay. Because, rightly so, this interface is versatile and can go on many different computers.
Exactly. At the moment he travels with the Commodore 64, because it has its own connector. Soon I will make a small interface that will convert this bus, so with the double connector, it will convert it into the ZX Spectrum bus, so it will then also be possible to load the Spectrum ROMs and put the interface.
This is the starting point, and little by little we will develop.
Well, but you've already developed a lot of the software, because you already have the cartridge reader.
Yes, there is the cartridge reader, there is the floppy emulator, there is the standard serial for those who have to work with modems and BBSs, therefore the standard Commodore one, the fast 9600 serial and the external serial, which goes up to 38,400. These are all already emulated at the moment.
Ok.
I'm working on the REU part, which is the memory extension interface. And then, if there is anyone who wants to contribute...
That's right, it would help you, because doing all these things actually takes a lot of time.
Oh yes, I have little free time, so…
But going back to stand-alone mode: is there a chip from here to VGA?
No, there are simply wires.
Ah, that is, inside…
Oh well, rightly so, with an FPGA, as you point out, you can emulate all the VGA signals.
VGA signals are emulated. The wires that would normally be connected to the Commodore 64 bus have been reassigned as useful functions to go to the VGA output, and from there I go to the monitor.
Show!
At this moment I have loaded the application to use the integrated modem. The Z-Modem modem emulation is done in Wi-Fi, and with that I am connecting to the RetroCampus BBS. We have Francesco Sblendorio's BBS here.
So, so at the moment the interface is acting as a drive, right?
It is acting as the drive, with which CCGMS is loaded, which is the program used to navigate inside the BBS, and in addition it is also acting as a modem.
It's acting as a modem and I have the application running. At this point we can also browse my site, because I am linked to the RetroCampus BBS. I, Valoroso.it, and this is the list of the latest articles, including the one on Varese Retrocomputing 2024.
And here is the largest monitor, in fact.
Thank you very much, Lorenzo, it was a pleasure! Please, subscribe to the channel, activate the notification bell and also watch the other videos relating to the interviews of Varese Retrocomputing 2024. Hello. HI!