Failed Optical Stick- http://www.emuunlim.com/doteaters/play2sta5.htm
Berzerk/Frenzy Multi-PCB (available July 2013)- Youtube
Berzerk Silk-Screen Marquees:
Why is there a slow and fast version of Berzerk?
- per Grant T- RC28 Slow Bullets is not a prototype, it was the first version of the game that was available to arcades. When Stern saw the success of RC28 Berzerk they wanted to make it into a cocktail as well which the code didn’t have built into ability to flip the screen for cocktail mode. Also Stern got feedback from ops saying the game difficulty jumped too quickly because at 5,000 points Otto suddenly doubles in speed and you can not out run him. With those two pieces of information Stern got Alan McNeil to make the difficulty in the game not jump as fast and also got him to program the screen flop in the code instead of using a logic gate IC because it would save Stern several thousands of dollars in building cost. In order to be able to do both the screen flop and make the game ramp up the difficulty not as sudden Alan removed Otto’s doubling speed and made the robots have more colors. Also to be able to do this, he had to save as much ROM (Read Only Memory) hence why in RC28 Slow Bullets it says Corporation where as in RC31 Fast Bullets it just has the (C) instead, because it used that much less space.
Technical-So why does the speech do a pop ? (per JROK Feb 2013)
- Listen to the soundbytes in this song to notice the pop sound- Youtube
- Most of the info for how the S14001A is implemented can be found in the patents, 4384170 is very useful and the audio output can be found in fig.11d and 11e.
- The start point for the delta modulator adder ( 184H ) is ‘0111’ that’s output to the R2R DAC (186), so the “zero” point is 1/2 voltage. That’s true of the TTL implementation and the S14001A LSI. Jonathan Gevaryahu’s comprehensive write up on the S14001a also makes note of this.
- Moving onto the Berzerk speech board. Then there’s a digital volume control on the stern speech board, IC C6, and what happens, taking the ‘coins detected’ as an example, the game turns the audio volume to ‘4’ (midpoint), the speech chip is already putting out the 1/2 point in the audio voltage output so you get the ‘pop’ as when it turns on as the voltage jumps immediately to 1/2 maximum, a sharp spike in the audio out which is the ‘pop’. Then after playing the speech sets the volume to ‘0’, so suddenly you’re getting the reverse situation, the voltage is going from mid-point to 0.
- You’ll see two sharps spikes in the audio. This could be fixed two ways, first it could be software with ramping up the audio volume, over a few frames 1 step at a time, so you don’t get a hard voltage spike, then ramp down when you’re turning it off, or with some more aggressive analog filtering on the audio output, like an anti-turn-on-pop filter.
- I actually fixed this issue in the JROK FPGA implementation so it doesn’t pop. Saying that I could put it in as an option, “Annoying Audio ‘POP’: On/Off”
Click the image below and look closely!
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