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Member Since 29 Sep 2005
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#3512304 New Demo release - MemoPad 480i

Posted by Rybags on Tue May 17, 2016 5:37 AM

I'll have a dig around, been a while since I created anything with it.


Not sure if there's any one source documenting the method.  What it comes down to is some cycle-precise stuff over 3 scanlines or so, and the before/after part of looking after the display.


And, no, don't want to keep it secret.  Would be so good if 480i support came to programs like RastaConverter and G2F, that would help make it more widespread to say nothing of helping to put C64 into it's (2nd) place.

#3511018 Atari 1090XL Schematics?

Posted by Rybags on Sun May 15, 2016 8:49 AM

There's various pictures around.  A few good ones I found here http://blog.3b2.sk/i...ion-System.aspx

shows plastic retainers at front and PC-style removable slats at the rear.

#3509934 Stretch Missile across the full width of screen

Posted by Rybags on Fri May 13, 2016 10:57 AM

From what I can gather you can only shut it off by changing size to a value other than 2 or when the object is triggered for redisplay when the HPOS comparitor matches.


Earlier explanation of mine a bit out.

Kernal loop starts.

Just after WSync, missiles 0/2 are positioned at HPOS=0C.  Colours - Missile 0 is black, Missile 2 is red.

SIZEM set to 33 then 22 which makes the 2 missiles persistent.  Due to M0 priority over M2, the display is black.

The kernal then sets each missile to the trigger position which will empty the shift register and stop display of each.  Missile 0 (black) ends where the triangle starts.  Missile 2 (red) is the triangle.  The position change for missile 2 empties it's shift register at the end of the triangle.

Then repeat for each scanline.


Explanation of PM persistence bug on pages 100-101 of the 2016-03 Altirra HW reference manual.

#3509705 Rob Hubbard Atari Music on c64

Posted by Rybags on Fri May 13, 2016 1:08 AM

I would think it's just running the Atari code which in turn writes to Pokey shadow registers.

Then a translate routine to approximate on SID.

Chances are they're using stuff that was ripped to begin with, ie someone hacked the music from the original Atari games then put into standalone executables.


What could be tricky though... since SID has the ADSR you can't always have a note start straight up on a voice.  Possibly there's a bit of AI going on to work out if the previous sound needs to be gated into release before putting the new one in.



OK, there's a thread on Lemon64 about it - I've asked the questions over there http://www.lemon64.c...ic.php?p=733915

#3509681 Rob Hubbard Atari Music on c64

Posted by Rybags on Thu May 12, 2016 11:40 PM

I think all those were on C64 anyway.  I don't know what system he did first though, but I heard of him on C64 well before Atari.  He was one of the biggest names in their music scene in the day.

#3509674 Best 5.25 floppy disk brand

Posted by Rybags on Thu May 12, 2016 11:15 PM

I haven't checked mine for a few years.


Possibly the majority brand of my collection is Memorex.  I found them to be pretty reliable.  I think I had one 10 pack of Fuji which I actually found to be of good quality.

Verbatim I found to be OK too but don't have too many.


Funny thing is in the modern day, I found Verbatim to be the best of the generic DVD-R.  TDK I stuck with for a while but dumped them after I bought 2 lots which were just pathetic.  Kodak I have bought as well and found to be good especially since they went under and went cheap on stock clearances.

Though the thing with DVDs is there's only a few fab plants and most branded ones are outsourced and suppliers will often change.

#3509620 Rob Hubbard Atari Music on c64

Posted by Rybags on Thu May 12, 2016 9:05 PM

Hmmm... most of those songs are somewhat prominent in the use of just pure tones.


The poly sounds, really the choice is among using sawtooth, different pulse wave, possibly noise for some very high or low freqs.  In theory you could use timer IRQs and emulate low pitched poly perfectly at some CPU cost, though generally Atari uses mid-high range poly stuff for music.

As it is, SID will cover most of the useful frequencies which most Pokey tunes using 16-bit or 16 KHz mode for music.


But on the other hand... I should think they'd have trouble with stuff relying constantly on 4 voices (or are they using 2 SIDS?)

They would have trouble with anything that's heavy on Pokey filter usage (SID filtering is completely different).

They would have trouble with anything that's heavily reliant on poly type notes rather than pure tones.

#3508181 Atari 1090XL Schematics?

Posted by Rybags on Tue May 10, 2016 10:52 PM

Yep, ISA would be fairly simple.  Problem is though they're getting rare to the point where you couldn't really do a public project where a given card is expected to be used, maybe early Soundblaster but can't think of any others.

#3506607 Atari 1090XL Schematics?

Posted by Rybags on Sun May 8, 2016 7:52 PM

ed - misread title, thought it said 1064.


ed2 - Supposedly Curt has schematics, no idea if he's publicised them http://atariage.com/...l/#entry1315527


Found elsewhere on AtariAge, technical notes with some handy info but no schematics.

Attached File  1090XL Technical Notes.pdf   110.71KB   152 downloads

#3506239 How do I navigate Sparta Dos subdirectories in Assembler?

Posted by Rybags on Sun May 8, 2016 7:02 AM

XIO is a standard CIO call e.g. XIO <cmd>,#<iocb>,<aux1>,<aux2>,<fspec>

Usually "Special" command is assumed when using this in Basic.  The difference between special commands and the normal range of GET/PUT types is that the IOCB doesn't need to be already opened for the special commands to work.


From assembly POV:

Store byte <cmd> into ICCOM

<iocb> as usual passed in X register (multiplied by 16)

<aux1/2> auxilliary byte #1 and #2 values into ICAX1/2

<fspec> device/file specification, as per procedure if issuing an OPEN command.  Filespec is only needed if the IOCB isn't already opened to the required device.

#3504300 Is this a replica OSS cart?

Posted by Rybags on Thu May 5, 2016 7:35 AM

Reported, I request others do the same.

This guy is obviously (title = Atari OSS Mac/65 with DDT Cart - VERY RARE) trying to pass this item off as if it's a rare retro find.


People like this with no rights to the software and spending 20 bucks and trying to triple their investment for next to zero work... need to be stopped.

#3503687 Manic Miner released!

Posted by Rybags on Wed May 4, 2016 4:52 AM

IMO it's not the sort of game you should have such cheats going on.  Finishing with god mode is no accomplishment whatsoever.


The way to get through would be to use save states at each level end.  It's still cheating but at least you can say you actually finished each level without altering the program.

#3502484 WIP Frake of Bemer

Posted by Rybags on Mon May 2, 2016 12:42 AM

Similar game to Millipedes http://www.atarimani...edes_13847.html


I created the concept of this game.  Mixture of normal, poison, bonus mushrooms.  The object is to grab all the bonus objects to end the level, the good objects make you grow longer  but while doing that the poison ones which cause you to shorten become more numerous and block your progress.

#3500908 Atari OS and Hardware Manuals - Get them here

Posted by Rybags on Fri Apr 29, 2016 9:31 AM

It might be the Field Service Manual (not sure as I've only got a PDF which is a partial scan).


Maybe just show pics of a few of the contents pages.


In the field service manual, example pages:  1-8 MPU pin assignment diagram

1-9 Antic pin assignments

2-3 400 motherboard silkscreen

#3500890 Atari 800 : unknown cart

Posted by Rybags on Fri Apr 29, 2016 9:10 AM

HM6116 are 2K SRam chips.  AM2966 is an octal dynamic memory driver IC.


What the card is for, no idea.  Weird that a memory slot would have something with only 4K occupying it.

Maybe it's some sort of printer buffer.  Or maybe some sort of interface that allows high speed data transfer to another computer using the 4K as a buffer.