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Member Since 29 Sep 2005
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#3029350 Centron 3D Official web page completed. Info + Pics

Posted by Rybags on Fri Jul 11, 2014 9:43 AM

The question I have is why/how so quick to get this Amiga video up yet the game was supposedly finished for the XL but no video of gameplay, only obviously fabricated screenshots.

#3029285 How to find out what system your floppy game is for...

Posted by Rybags on Fri Jul 11, 2014 8:22 AM

Entirely possible as well.  Also, many multi-disk games will appear to boot from the non-boot disk and get to a point and hang.

#3029267 How to find out what system your floppy game is for...

Posted by Rybags on Fri Jul 11, 2014 8:04 AM

You'd want to be holding Option until the blue startup screen to disable Basic.


Pre-XL games, it's a must do in many cases, later on a lot of the programmers were just lazy and printed it in the manual to do so rather than spending the entire 8 bytes or so of program code to do the same.

#3029231 Altirra and multiple cores

Posted by Rybags on Fri Jul 11, 2014 7:07 AM

It comes down to a case of dependancy - at each cycle the program can change a single hardware register that can affect the behaviour of most of the machine.

And a case of accuracy - no point having emulated Antic+GTIA render an entire scanline worth of pixels if the CPU goes and changes stuff midway - it effectively makes most of that work pointless because of the changed state.


There's stuff that could get farmed off to other cores - I think Avery explained some of it elsewhere - but the overall benefit of farming that work out isn't particularly great.


In theory you could have 4 threads e.g. doing CPU, Pokey, Antic, GTIA - but the thing is that each thread would have to wait on the others, never getting a cycle beyond what's going on with the others.  That means some inter-thread communication required, not to mention the fact that each thread needs to be active which in a multitasking Windows environment is no way guaranteed.  Alternatively of course, a thread that's completed it's task can go into a wait and allow the other thread/s to complete their little bit of work unit on the same core (assuming the Win scheduler executes it).

At the end of the day, a bunch of extra complication in the overall system, possibly for not too much gain.

#3029172 Centron 3D Official web page completed. Info + Pics

Posted by Rybags on Fri Jul 11, 2014 3:00 AM

Actual screenshot... I really, really doubt that.


An AGA machine could do it, but no way with OCS or ECS.  You can tell just by the shades of the car that's way more than 4 bits per channel palette depth.

Even on AGA 256 colour mode, there'd need to be some tricky palette loading and HAM8 would unlikely provide the ability to do some of those adjacent colour changes.

#3025687 What would you use a Pentium 4 computer for?

Posted by Rybags on Sun Jul 6, 2014 1:36 AM

Pentium 4 is a pretty broad description since they made them for so long and had 3 socket form-factors.


The early ones are barely worth a pinch of shit, the Athlon XP of the time generally wiped the floor with them, and RDRam motherboards aren't exactly desirable.


The Socket 478 ones are worthwhile if the P4 itself is >= 2.8 GHz speed.


The LGA775 were the last/best - if the motherboard is a later one that supports the Core2 CPU then there's an easy upgrade path.


Any half serious machine running WinXP, you really want at least 2 Gig of RAM - but if it's just to serve as an emulation/HTPC box then 1 Gig or even 512 Meg would be OK.


But the thing is, these things are so common that they're practically throwaway items.


I'd not worry too much about Hyperthreading.  They actually discontinued it for a time.  Real multicore of course is much better.

#3025624 VBXE

Posted by Rybags on Sat Jul 5, 2014 10:55 PM

Sync is composite sync which is sourced from the motherboard.  I had the same problem first up, had forgotten to put in that connection.  If the monitor has some selection ability, it'd need to be seperate composite sync, VBXE doesn't use Sync on Green, or seperate H/V Sync.

In some cases where only seperate syncs are provided, the usual is to tie the CSync output to HSync on the monitor.


If you're getting sync problems with normal video as well then that'd indicate a problem somewhere else.


Colour adjustment Pot will make absolutely no difference to RGB, VBXE video is independant except for the shared CSync.


Sound - I guess you source that from the normal monitor port?  In any case, I'd be getting the video output right before worrying about sound.

#3025302 Centron 3D Official web page completed. Info + Pics

Posted by Rybags on Sat Jul 5, 2014 9:57 AM

I feel a rude awakening might be in store... really there aren't that many people who use LCD TVs with their older computers.

#3022871 RAM Chips in some of your favorite vintage computers!

Posted by Rybags on Tue Jul 1, 2014 5:21 PM

They're also used in early XE models, later models and XEGS use 4-bit RAM ICs.


So long as access time is under about 250 ns 4164 RAM should be good for Atari.  C64 requires slightly quicker time.

By the time these ICs were in use, 150 ns or better was a common speed.


A common upgrade was to replace 64k with 256k chips and connect the additional address pin, also requires extra external logic.

#3021654 Z80 vs. 6502

Posted by Rybags on Mon Jun 30, 2014 1:13 AM

The fact of the matter though is that when they were actually relevant in the computer industry, there were much better 6502 machines than Z80 offerings.


Atari, C64, Apple IIgs - top of the pile.  NES, SNes - top of the pile in their console generations.


The best Z80 offerings were probably the Sam Coupe and MSX2.   Sam Coupe about 5 years after the 16-bit generation kicked off, so too late for the party.  MSX never really made much impact outside Japan.


There's modern day incarnations of many of the older CPUs - 6502, 68000 included.  Intel even made an embedded version of the '386 until not so long ago.

#3019321 Hard-reset button

Posted by Rybags on Thu Jun 26, 2014 8:32 PM

Really, it's probably just easier to burn or flash a custom made OS that has a coldstart key sequence.

The XL keyboard routine has a bunch of crap that's only usesful for 1200XL, get rid of that and have something like Shift + Option + Delete.

#3018332 No sound from my Atari 520 STfm... Help please :)

Posted by Rybags on Wed Jun 25, 2014 7:25 PM

Check the monitor plug, 13 pins in a small area so pretty delicate.

#3016139 Centron 3D Official web page completed. Info + Pics

Posted by Rybags on Mon Jun 23, 2014 8:33 AM

Except for the backdrop all the level screenshots look exactly the same.

#3016003 CENTRON 3D - End of level screen shot

Posted by Rybags on Sun Jun 22, 2014 11:22 PM

3D (or "2.5D") as seen in Project M and other projects is entirely possible for a game project, especially at a lower resolution.


Of course doing the projection and basic movement mechanics is the easy part - turning the whole thing into a game worth playing is the challenging part.

Given the power of the Atari and availability of less demanding lores modes, really there is a distinct lack of such games.

#3014830 CENTRON 3D - End of level screen shot

Posted by Rybags on Sat Jun 21, 2014 2:02 AM

There was actually a hardware upgrade (from Poland?) that allowed enhanced colour and worked by pumping register writes to GTIA much faster than the CPU could otherwise do.

Once VBXE came along though, it fell by the wayside.