Introduction: Djaybee

[djaybee]

Hi everyone!

I guess it's time for an introduction. I'm Jean-Baptiste, also known as JBQ, and, when I write demos, my nickname is Djaybee from the Megabusters. I grew up in France, spent about half of my life in the USA, and recently moved back to Europe; I now live in Greece.

The first computer to land on my desk was an Amstrad CPC 464 with a DDI-1, which I got in June of 1984 as a loaner from a local computer club that would open a few months later, that had received their machines early, and that let me borrow one machine all summer. I had no games for it, only the BASIC manual, so my only option to use it was to learn programming.

Eventually my parents bought a CPC 6128 in late 1985 (I got to borrow a TI 99/4A in the meantime). I still programmed a bit, but as a pre-teen I guess I spent more time playing than programming.

Then came an Atari ST, where I learned assembly (inclduing releasing a few demos), and we added an STe and even a Falcon030 to the family. I studied a bunch of computer science and software engineering in university, got a BeBox along the way, got a job as a software engineer, and from that point I was programming so much at work that I stopped having personal projects.

Over the next 20 years, my job evolved such that I wouldn't do any programming any more at work (though I still work closely with people who do), and I started to get back into programming as a hobby. Today, I mostly use Chromebooks, an XBox for games, and my coding happens on a desktop PC running Linux.

This year being the 40th anniversary of my programming debut, I am trying to code something to mark the occasion. Since my debut was on the CPC and since it's also the CPC's 40th anniversary, I figured that I would try to write a small demo for the CPC. In the process of learning about the CPC, I've gained a lot of respect for Amstrad's engineers, and for the people who wrote commercial software for the CPC. I am discovering that the CPC's greatest asset (its rich graphics modes) is also its weakness (those graphics are heavy to move around). I don't have anything to show yet, as I'm currently facing the harsh reality that my plans might be too ambitious and might need to be scaled down. I'm not giving up yet, though, and I still hope to have something running at some point.

[Anthony Flack]

Welcome!

The CPC's greatest asset may be the CRTC, depending on how you use it. It's one of the only tools you have to deal with those heavy graphics without pushing it all through the Z80.

[rexbeng]

Hey, welcome. I gather we count you as part of the Greek scene, then? 

[cwpab]

got a BeBox along the way

Pics or it didn't happen

[djaybee]

Welcome!

The CPC's greatest asset may be the CRTC, depending on how you use it. It's one of the only tools you have to deal with those heavy graphics without pushing it all through the Z80.

Haha, well, there aren't many tools available, so it's either that or doing everything in code. What I like is that there's quite a good gap already between what Amstrad did and what can be done with conventional programming, and then there's an even larger gap when you start to race the beam.

I can imagine Motorola's engineers asking "you did WHAT with our 80x50 text-mode chip?"

[djaybee]

Hey, welcome. I gather we count you as part of the Greek scene, then? 

I guess so indeed

[Anthony Flack]

Basically hijacking the CRTC with the CPU, which went against the intended purpose of the CRTC to be fair.

But it's too bad those Motorola engineers didn't think to let us read the internal scanline counter. Or that the gate array couldn't help us out a bit more there. The interrupt every 52 scanlines is both tremendously useful and annoyingly limited.

But that is the fun of it.

[Anthony Flack]

I remember when Sorcery came out, the Mode 0/Mode 1 split was much admired at the time. 

[cwpab]

What I like is that there's quite a good gap already between what Amstrad did and what can be done with conventional programming, and then there's an even larger gap when you start to race the beam

I just learned about the expression "racing the beam", thanks.

[skylas]

Hi everyone!

I guess it's time for an introduction. I'm Jean-Baptiste, also known as JBQ, and, when I write demos, my nickname is Djaybee from the Megabusters. I grew up in France, spent about half of my life in the USA, and recently moved back to Europe; I now live in Greece.

The first computer to land on my desk was an Amstrad CPC 464 with a DDI-1, which I got in June of 1984 as a loaner from a local computer club that would open a few months later, that had received their machines early, and that let me borrow one machine all summer. I had no games for it, only the BASIC manual, so my only option to use it was to learn programming.

Eventually my parents bought a CPC 6128 in late 1985 (I got to borrow a TI 99/4A in the meantime). I still programmed a bit, but as a pre-teen I guess I spent more time playing than programming.

Then came an Atari ST, where I learned assembly (inclduing releasing a few demos), and we added an STe and even a Falcon030 to the family. I studied a bunch of computer science and software engineering in university, got a BeBox along the way, got a job as a software engineer, and from that point I was programming so much at work that I stopped having personal projects.

Over the next 20 years, my job evolved such that I wouldn't do any programming any more at work (though I still work closely with people who do), and I started to get back into programming as a hobby. Today, I mostly use Chromebooks, an XBox for games, and my coding happens on a desktop PC running Linux.

This year being the 40th anniversary of my programming debut, I am trying to code something to mark the occasion. Since my debut was on the CPC and since it's also the CPC's 40th anniversary, I figured that I would try to write a small demo for the CPC. In the process of learning about the CPC, I've gained a lot of respect for Amstrad's engineers, and for the people who wrote commercial software for the CPC. I am discovering that the CPC's greatest asset (its rich graphics modes) is also its weakness (those graphics are heavy to move around). I don't have anything to show yet, as I'm currently facing the harsh reality that my plans might be too ambitious and might need to be scaled down. I'm not giving up yet, though, and I still hope to have something running at some point.

Welcome!!!

[djaybee]

got a BeBox along the way

Pics or it didn't happen

I found my BeBox.

[Gryzor]

Welcome, and thanks for sharing your story! 

Whereabouts in Greece are you located? 

Also that's a very cool BeBox....

[djaybee]

Welcome, and thanks for sharing your story!

Whereabouts in Greece are you located?

Also that's a very cool BeBox....

I'm in Preveza, so I'm a few hours from Athens, close enough that it's easy but far enough that it has to be planned a tiny bit.

As for the BeBox, it's even more fun with a H0BBIT BeBox motherboard.

[Gryzor]

Welcome, and thanks for sharing your story!

Whereabouts in Greece are you located?

Also that's a very cool BeBox....

I'm in Preveza, so I'm a few hours from Athens, close enough that it's easy but far enough that it has to be planned a tiny bit.

As for the BeBox, it's even more fun with a H0BBIT BeBox motherboard.

Damn that's a rare beauty! 

If you ever do come to Athens do drop me a pm if you wanna grab a coffee😊

[djaybee]

I just learned about the expression "racing the beam", thanks.

The Atari 2600 is a great machine on which to learn how to race the beam, since that's the only option. Even for a very simple game like Combat (bundled at launch), you need to be counting lines, and you need a little bit of cycle-accurate code to position the sprites and to display the scores. Luckily, the hardware has a few features that help.

Racing the beam isn't too bad on the CPC, with the caveat that the interrupts that you can synchronize with are quite coarse. The palette is easy to change, albeit slow, as is the display mode, and the CRTC lets itself get re-programmed mid-frame for some very interesting effects.

I've raced the beam a lot on the Atari ST, where synchronizing is both easier and harder than on the CPC (depending on what you want to do). Racing the beam is a must-have for overscan or for hardware scrolling that the CPC gets for free from the CRTC, so it's a lot more common there, but at the same time, interrupts are flexible enough and fast enough that you don't need to race the beam for mid-frame palette changes. The Spectrum 512 graphics format relies on racing the beam to change most of the palette 3 times per line (if I remember correctly).

It can be done on the NES as well, where I have a vague memory that it's annoying and limited, it is a must-have for split-screen scrolling such as in Super Mario Bros, but doing a single split doesn't require that much effort. On the other hand, split-screen scrolling is almost the only thing you can do, since the NES is super picky about only allowing access to the graphics chip (PPU) during vblank.