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MegaCD development kit video on Computerphile

#1 User is offline BigEvilCorporation 

Posted 03 December 2016 - 03:43 PM

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Hi all!

I did a video with Computerphile showing a MegaCD devkit and a demonstration of it working. I thought it might appeal to some people here :)/>



Also please do take a look at my game on Kickstarter if you like the thing!

#2 User is offline Overlord 

Posted 03 December 2016 - 05:31 PM

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I fixed your video embed.

Great watch, by the way! Though annoying that you kept calling it Genesis when it bloody says Mega Drive on the unit itself =P

#3 User is offline BigEvilCorporation 

Posted 04 December 2016 - 07:11 AM

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View PostOverlord, on 03 December 2016 - 05:31 PM, said:

I fixed your video embed.

Great watch, by the way! Though annoying that you kept calling it Genesis when it bloody says Mega Drive on the unit itself =P


I swap between the two, that channel has quite a large American audience. They RIPPED into me for my pronunciation of SCSI though :(

#4 User is offline MarkeyJester 

Posted 04 December 2016 - 12:20 PM

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That hardware looks beautiful!!

As a fellow 68k and Mega Drive programmer, the one thing I'm not too comfortable with, is the fact that the vector table and the registers need to be setup in a certain way to operate the debugger. Now, regarding the register setup, once the initialisation is done, are the registers now 100% free? ...or are a few of the registers (say address registers) needed throughout the game to allow the debugger to function? I wrote a game for the Mega Drive (with some Mega CD support) called the Chaos Layer some years ago, but, I needed every register I could get my hands on to keep it as optimal as possible, especially with some of the effects I was planning to do. If I were to obtain this, would setting up the debugger for my game require a lot of rewriting of code?

One more question, does this include (or do you intend to include) a debugger for the Z80 sub-CPU in the Mega Drive itself?

Either way, this looks incredibly useful, and what I do appreciate is the fact that you have a proper hard case shell, to accommodate the new components inside. It doesn't look like some dev-kit made in someone's garage, it looks like a solid piece of equipement, cool stuffs~

#5 User is offline BigEvilCorporation 

Posted 04 December 2016 - 04:17 PM

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View PostMarkeyJester, on 04 December 2016 - 12:20 PM, said:

That hardware looks beautiful!!

As a fellow 68k and Mega Drive programmer, the one thing I'm not too comfortable with, is the fact that the vector table and the registers need to be setup in a certain way to operate the debugger. Now, regarding the register setup, once the initialisation is done, are the registers now 100% free? ...or are a few of the registers (say address registers) needed throughout the game to allow the debugger to function? I wrote a game for the Mega Drive (with some Mega CD support) called the Chaos Layer some years ago, but, I needed every register I could get my hands on to keep it as optimal as possible, especially with some of the effects I was planning to do. If I were to obtain this, would setting up the debugger for my game require a lot of rewriting of code?

One more question, does this include (or do you intend to include) a debugger for the Z80 sub-CPU in the Mega Drive itself?

Either way, this looks incredibly useful, and what I do appreciate is the fact that you have a proper hard case shell, to accommodate the new components inside. It doesn't look like some dev-kit made in someone's garage, it looks like a solid piece of equipement, cool stuffs~


All the registers are free for use once the devkit setup is done. The only meaningful change is to inject the address of the SNASM handler into the TRACE interrupt, the rest are just niceties (passing control of all exception handlers to the debugger, etc). I can't speak for the MegaCD side though, I don't have it fully working yet, but I would assume it would be designed not to restrict the coders.

There is Z80 debugging functionality but I don't have the license for the Z80 debugger (the little battery looking thing on the SNASM2 card) - it won't even start up without one.

I didn't make the kit - it's an official one by Cross Products (a dev hardware company) made in 1992 - based off the SNASM2 tools.

#6 User is offline MarkeyJester 

Posted 04 December 2016 - 05:31 PM

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Ah right, thanks for the clarity on that, appreciated much~

#7 User is offline biggestsonicfan 

Posted 16 January 2017 - 10:09 AM

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Sega devkits outside of Saturn and Dreamcast have always been a mystery to me. I've always wanted to inspect arcade hardware dev kits, but I doubt I will ever see a working older one. Thanks for the share!

I am thinking of learning assembly as I pick up computer languages rather fast (better than actual spoken languages, actually), however I want to program for the Intel i960 (Model2 homebrew anyone?), but I am worried the same instruction sets may have different meanings in the i960 and am limited to the mercy of the official Intel documentation. Any advice?

#8 User is offline MarkeyJester 

Posted 19 January 2017 - 07:12 AM

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My advice would be not to worry about that, just learn the language first, minor differences such as different ccr flags being set/cleared/changed you'll pick up as time goes on, what's important is to understand the basics. I wouldn't let the small things get you off course or off balance.

But, that's just my advice, I've only handled a handful of CPUs myself, 68k, z80, x86, and haven't come across major differences between revisions of the same CPU. You "should" be fine.

#9 User is offline Natsumi 

Posted 19 January 2017 - 01:33 PM

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I am curious about how is developing games in inferior PC hardware compared to nowadays specs, how long does assembly take, and how much tool automation you can afford to do without making the assembly process way too slow?

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