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Member Since 29 Sep 2005
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#3191287 Pole Position + voice + VBXE enhancement

Posted by Rybags on Wed Mar 4, 2015 10:10 PM

This is one that stalled as I was having problems - it's before Altirra became the predominant emulator, the debugger would have the problems sorted in short order.

Also I was doing it as a patch job which really is a painful way to do game enhancements.


It's one of those things on the backburner that I hope to pick up again.  At the least to just put the speech in that it should have had from the start (OK, it would have made for a 32K game but who cares?)


There's other stuff around to test VBXE.  Some included in the Release package from candle's site.

Some of the stuff I've done is in there, and downloadable here too.  From memory:

- Moon Shuttle (Basic + asm game with some VBXE enhancements)

- Quadrillion (port from C= Plus4 game, mainly uses VBXE for colour mapping, 160x bitmap with more colours)

- Spectipede (port from C= Plus4 game, uses legacy hires with VBXE colour mapping enhancements)

- Moon Cresta (port from 7800 game in progress, uses VBXE bitmap 320x mode with multiple colours)

#3190349 Cartridge base game, save file to disk without loading DOS first

Posted by Rybags on Tue Mar 3, 2015 4:22 PM

I'd just raw dump sectors - practically every other game out there does so.


Allowing a Dos to load opens up too many scenarios to have to cope with.  Having your own Dos means trying to cater for multiple different storage system types which can quickly turn to bloatware.

Other thing to consider is many people will just be using emulation devices, makes it easy to mount disks anyway.

#3190097 I thought I'd killed my 65XE. Now I'm not so sure.... help?

Posted by Rybags on Tue Mar 3, 2015 8:32 AM

It's usually the case of being more economical to just buy a replacement machine that works then keep the faulty one for parts.

#3190067 I thought I'd killed my 65XE. Now I'm not so sure.... help?

Posted by Rybags on Tue Mar 3, 2015 6:55 AM

GTIA usually has some registers in randomish state on powerup, usual is dark brown/red or green.  Not changing from that indicates the OS isn't starting up at all.


Machine randomly working - possibly you've fried the MMU but it still has signs of life.  These things are easiest diagnosed if you have another machine so can test swap components into it.

So really, might be MMU, CPU, OS Rom , PIA or maybe even Antic. Or might be something else like a passive component.

#3190020 Atari Limited 90 day warranty

Posted by Rybags on Tue Mar 3, 2015 3:15 AM

Call Warner Bros and pay some disrespects.

#3184811 !Looped Horizontal Scrolling

Posted by Rybags on Tue Feb 24, 2015 8:10 AM

For a looped horizontal scroll like you describe to work properly, you'd want to avoid the display crossing the page boundary.

As such, you'd want the LMS value low byte to stay well under a value of 255, in fact for a HScroll enabled 40 column mode you'd probably want it to not exceed about 208 - consider 48 bytes fetched in such modes in normal or wide width.


Assuming you want a smooth looping landscape, you'd want to repeat the initial screen data at the end, and if the value exceeds the threshold of ~ 208, then set it back to zero.


In doing this, you shouldn't need to worry about the Antic 4K problem, since you'd not even be crossing 256 byte boundaries.

#3184723 Controlling both Joysticks independently?

Posted by Rybags on Tue Feb 24, 2015 2:54 AM

Upper 4 bits are Port 1, lower 4 bits are Port 2.


Generally you want to AND or bitshift so that the controller in question occupies the lower 4 bits, ie read the SWCHA register then do an LSR A 4 times to get port 1, or AND #$0F to get port 2.

That gives the dual advantage of filtering out what's happening on the other port as well as allowing you to use the same program code to handle both joysticks.

#3182439 Best 5.25 floppy disk brand

Posted by Rybags on Sat Feb 21, 2015 12:54 AM

I've found Verbatim to be good all round in all the types thru 5.25, 3.5, CD, DVD.


Most of my 5.25 are probably Memorex and can't recall having any trouble or chucking any out, though I've had Memorex DVDs that have been shockers with more than 2 in 50 failing straight up.  Though DVDs have only few fab plants and a given brand might have multiple media IDs that carry the same sticker.

Also have some 5.25 Fuji which have stood up well.


Really, the low densities used for Atari SD and ED barely pushed most media which is probably why it's got a near 100% retention rate if kept in good conditions for >30 years.  It's once you put 720K and beyond onto a 5.25 floppy that the failure rate goes way up.

Similar with 3.5" - the lower 720-880K used by early PC, Mac, ST, Amiga stand up reasonably well but the 1.44 Meg HD ones would often fail in a matter of months.

#3171068 RP9 File Format

Posted by Rybags on Thu Feb 5, 2015 11:09 AM

I'd prefer an approach similar to how MAME does it.


Keep assets like Roms, Samples, Screenshots, Manuals, Artworks seperate.  Make it up to the user whether or not they want the extras included within their overall emulation library.

As nice as it would be to have an emulator setup where you had the manual, screenshots, box art within easy reach, it has the potential to become massive bloatware where an Atari collection might take 20 Gig instead of 2.


A database file would be preferable IMO - for each game have cataloged the common name for launchable ATR, XEX versions.  Allow the user to be able to asssociate other files to a given game (e.g. for self-modified versions).

#3167007 Whats difference between commodore 64, amiga, tandy

Posted by Rybags on Sat Jan 31, 2015 10:36 AM

C64 has only 8 function keys (although represented on 4 actual keys).

Amiga has 10 function keys.

Tandy 1000 has 12 function keys.


Aside from those things, they're practically identical.

#3166626 Project Veronica

Posted by Rybags on Fri Jan 30, 2015 8:21 PM

The logical way to do sound would be to pre-process.  e.g. for SID emulation, just calculate the resultant sample values for each upcoming scanline with the '816 and have them ready for the 6502 to read via Timer IRQs in the next frame.  At 15 MHz, such processing should allow relative HiFi vs existing methods at probably 20% or less CPU expenditure of the '816.

That leaves the remaining cycles for the '816 to do rendering, calculating, other stuff.

#3165301 Another very early WIP

Posted by Rybags on Thu Jan 29, 2015 4:15 AM

Nice assortment.


For button assignment, you need hyperspace as a non-fuss straight up thing, smart bomb also but slightly less urgent.


I'd go with RT's idea except straight up for hyperspace, held down for smart bomb.

Of course, best would be to allow the user to configure to their own needs.

#3164420 BASIC Ten-Liners Contest 2015

Posted by Rybags on Wed Jan 28, 2015 3:53 AM

Probably a good idea to publicise it at Lemon64.com as well - it's probably the biggest C64 forum.


I'll try and get in again, hopefully with more entries, and take advantage of TBXL this time.

C64 would be really interesting given the 80 char/line limit and somewhat simpler Basic.  But I suspect we could implement similar tricks to A8 to cram more into each line.

#3159294 Reds1F14 and Kratters31 are no more

Posted by Rybags on Thu Jan 22, 2015 2:04 AM

The shit-bagging that went on over Centron3D was 100% deserved.


He carried on as if he was the only person in the world developing for Atari, he treated people here as if they were just dipshit collectors with little technical knowledge.

He made claims about his graphical mode and I and others uncovered the truth and revealed it not to be the marvel some thought it to be.

Bottom line - we called him on his bullshit and he just went psychotic about it.  The Atari scene is better off without him.

#3157867 I wonder why no one posted this already... NEAR

Posted by Rybags on Tue Jan 20, 2015 6:10 AM

Some real nice parallax effects there, Cananbalt is half done for us in that first part, and the grafitti tunnel at the end is pretty amazing.  Like the rotating cubes also.


One annoyance though, and something we all need to learn from - since we have modern TVs and emuation that shows more overscan than the old days, a couple of NOPs are a good idea if time allows after WSYNC when doing the colour effects to avoid the next colour appearing on the current scanline.