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Member Since 21 Aug 2008
OFFLINE Last Active Today, 9:36 AM

Posts I've Made

In Topic: Thanks and Cheers to A8 coders & creators

Sun Apr 15, 2018 10:17 PM


In Topic: Vanguard - diagonal movement?

Wed Apr 4, 2018 11:51 PM

A shabby attempt:


Attached File  vg-hack.xex   21.01KB   21 downloads


There seems to be a lot of the code that assumes only four directions. So I simulated diagonal movement by issuing up/down and left/right in alternating frame pairs. Unfortunately, this makes the diagonal movement seem sluggish.


The code for dealing with the 5200 joystick appears to have been left mostly intact. The conversion layer just inserts fake 5200 joystick values based on XL/XE PORTA values. I'm afraid I got confused trying to trace through all of this.

In Topic: Could PoKey do this

Thu Mar 29, 2018 12:19 PM


There's a thread here, but I couldn't find it on the first couple looks.

I know he was demonstrating a comparison between PWM and PCM.

I have the PCM file of exactly the same song, and the quality is lower.


I did find this thread about PCM audio experiments. Maybe the file is

in the thread and I just didn't see it (didn't spend much time looking).


PCM Audio Experiments


I made the Desireless - Voyage Voyage examples using phaeron's techniques as reverse engineered from his 60FPS demos. Original thread here. Some more examples using Bon Jovi here. Both rely on instantaneous XEX segment loads as found in emulators. They have gaps for loading on real hardware. I didn't know about the PCM Audio Experiments thread. Thanks for the pointer!


Unfortunately the PWM technique loses precision the higher the frequency. At 15Khz it has around 6.5 bits. So at 45Khz it would only have around 2 bits of precision assuming you could properly time everything. At that point it would be better to go back to volume-only mode which has 4 bits of precision.


Unrolled LDA/STAs could do about 13 AUDC updates per scanline which translates to about 195KHz. At that frequency you could apply some dithering to the 4-bit samples to increase the precision. If my math is right that would get you to about 6 bits of precision at 48Khz.

In Topic: Altirra 3.00 released

Sat Mar 24, 2018 10:29 PM

When I choose View -> Filter Mode -> Bicubic the screen goes completely black. I'm using 3.10-test14 on Windows 10. Anybody else having this problem? Altirra 3.00 works OK for me.

In Topic: THE!CART... New 128MB FLASH Cartridge

Thu Mar 8, 2018 8:42 PM

There's a space at the end of that URL that prevents it from going to the right page. Here is a working URL: link.



Please check out the video and the description here http://www.wudsn.com/index.php/productions-atari800/tools/thecart 

Best Regards, Peter.