Tuesday, July 15, 2014

Achievement Unlocked

Very few games for the Tandy Color Computer (CoCo) 1 and 2 had any sort of in-game music.  I presume that the case is the same for the Dragon, since the game libraries for the Dragon and the CoCo were essentially the same.  Many had some sound effects or even a tune or two, but CoCo games generally halted the game action while sounds were played.  Not too long ago, I was only aware of a couple of CoCo games that had continuous in-game music.  Now I know of one more -- Fahrfall!

Hard Time

The CoCo did not have any sound hardware beyond a couple of ways to driver the speaker directly from the CPU.  Where other machines had POKEY or SID or some variant of the AY-3-8910 to do the heavy lifting for audio, the 6809 was the CoCo's sound chip!  This provides some flexibility, but it does make producing audio a burden for the programmer...

I had feared that having in-game music would require a lot of hand-crafted code modifications to perfectly time audio updates according to cycle counts in the instruction stream.  Fortunately, there is enough time left in each frame to produce a reasonable (YMMV) audio stream.  The time spent running the code produces a low-frequency hum in the audio, making the overall sound seem a bit like the speaker is behind a fan.  The tone probably horrifies a lot of audiophiles, but I think it is a clear win versus no sound at all!  I hope others agree...

Another Beta

I was a bit apprehensive about releasing another beta.  It is no secret by now that I would like to do a cartridge release of Fahrfall, and I am a bit afraid that I might cannibalize my market by releasing a nearly complete version to the world for free.  Still, I want everyone to enjoy the new Fahrfall and more testing never hurts!

Real fans will still want the cartridge.  Besides, a few less cartridges sold will mean a few less cartridge cases for me to make!  Anyway...I may still squeeze in a feature or two before a cartridge gets released... ;-)



Today marks the middle of July, so we are half way through the Summer Challenge.  So far I have made good progress on my code development, but done very little documentation on the "arts and crafts" part of the project.  I definitely have some stuff to show there, and I think this seems like a good time to pivot in that direction.

So, get ready to learn a bit about casting plastic, sanding, drilling, applying stickers, etc...and as always, stay tuned!

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