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alex_79

Member Since 7 Sep 2006
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#4173572 Stella getting into details - Help wanted!

Posted by alex_79 on Sun Dec 9, 2018 3:09 PM

I got slightly different results than before for the two "Dig Dug" carts, but I also tried the old test rom again and got these new patterns as well!

I think it's just due to e.g. different temperature of the console and/or carts, while the address wraparound apparently makes no difference.

IMG_0239.JPG IMG_0240.JPG

 

The other carts behave the same as they did before.

Attached File  testSC_1_F_inv_RIOT.bin   4KB   20 downloads
 




#4172722 Stella getting into details - Help wanted!

Posted by alex_79 on Sat Dec 8, 2018 8:19 AM

I did some tests with real superchip carts and the results are NOT what I would have expected.

I hacked the test rom posted by Thomas so that it now runs from the RIOT ram and the test only starts after the console RESET switch is pressed. This allows to remove the cart containing the test rom (the Harmony in my case) and plug in the actual cartridge to test while the console is powered (WARNING! HOT SWAPPING CARTS CAN POTENTIALLY DAMAGE THE CONSOLE OR THE CARTS THEMSELVES. DO IT AT YOUR OWN RISK!)

I tested 9 different superchip carts and in all cases the value read from the write port doesn't seem to be affected by the last value on the data bus.

These are the results for two different "Dig Dug" cartridges. The pattern is almost stationary, with the exception of a few pixels flickering. I let it run a few minutes and didn't notice any change in behaviour.
IMG_0234.JPG IMG_0235.JPG

Super Football:
$FF everywhere, stationary
IMG_0237.JPG

Secret Quest:
$FF almost everywhere, initially stationary, then the black pixels start to flicker and finally it becomes all $FF (after 2-3 minutes)
IMG_0236.JPG

Dark Chambers:
All $FF

Desert Falcon, Crystal Castles, Stargate, Millipede:

All $00 (black screen)
IMG_0238.JPG

 

 

Here is the hacked testrom:

It will display a series of coloured horizontal lines. You can then unplug the cart with the testrom, and plug the one that needs to be tested. If the horizontal lines are still there, the console didn't crash and you can press RESET to start the actual test. (It seems that plugging in the cart sligthly slanted, so that the right part of the edge connector, where the ground pis are, makes contact first, helps reducing the chance of crashing. As I said,  if you want to try this, you do it at your own risk!)
testSC_ram.png testSC_ram_1.png
Attached File  testSC_RIOT.bin   4KB   26 downloads

Finally, here are a few dumps of the Stargate cart:


reading from 1000-10ff: eveything gets zeroed like with the test rom. The result is always the same after each power-cycle.

1000-10ff

0000:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0010:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0020:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0030:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0040:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0050:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0060:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0070:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0080:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0090:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00A0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00B0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00C0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00D0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00E0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00F0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 

Same as before, but using mirrors 5000-50ff. The result doesn't change, the last value on the bus doesn't cause a different behaviour. The result is the same after each power-cycle.
 

0000:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0010:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0020:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0030:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0040:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0050:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0060:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0070:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0080:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0090:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00A0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00B0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00C0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00D0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00E0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00F0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 

only dumping the read port (1080-10ff) results in random values. These are different each time the console is power-cycled.

1080-10ff 

0000:  86 D0 F0 E6 87 A5 87 C9 F8 D0 E8 A9 F0 85 87 A5 
0010:  82 C9 03 10 04 E6 82 D0 DA A2 F9 D0 02 86 9B BD 
0020:  E7 1F AD 00 F0 85 80 20 E8 00 E6 8B D0 EB E6 8C 
0030:  A5 8C C9 F8 D0 E3 A9 F0 85 8C A5 82 10 04 E6 82 
0040:  D0 D7 AD 20 02 AD 00 F0 85 80 20 E8 00 E6 85 D0 
0050:  F1 E6 86 D0 ED A9 F0 85 86 A5 82 C9 40 10 06 A9 
0060:  40 85 82 D0 DD C9 FF AD FF FF AD FF FF 85 80 20 
0070:  E8 00 A5 87 C9 FF D0 06 A5 88 C9 FF F0 09 E6 87 

finally I dumped skipping the first half of the write port, from 1040 to 10ff. The last 64 bytes of ram gets always zeroed, the first half is random and changing at each power-cycle
 

1040-10ff 


0000:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0010:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0020:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0030:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0040:  26 FD D0 E3 30 8D FA DD 91 A3 CC 75 D9 6A 71 EA 
0050:  1F 7C 93 C9 CA 0F 1C C2 1D A8 4B 71 10 1F 84 ED 
0060:  7A E0 F3 51 11 61 9A 4A F1 92 F0 D1 72 80 D9 5C 
0070:  63 2F 39 AD 3B 75 0E 6A 7B AF 0A 66 94 6F 17 7F 
0080:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0090:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00A0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00B0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 

All tests and dumps are made using a non modified PAL 2600jr. All carts are PAL.

 

EDIT:

Updated the testrom. The one I originally attached wasn't the latest version.

 




#4172294 Stella getting into details - Help wanted!

Posted by alex_79 on Fri Dec 7, 2018 11:54 AM

Same results with the Harmony here. I think Stellerator is correct: you're reading from a write-only address, so nothing is driving the bus and you (tipically) get the last value that was on it, that is the address MSB.
Probably the harmony slightly drives bit 6 high and that's why it is always set with the test rom. Some eproms might affect the bus as well.

 




#4159798 Aardvark for Atari VCS/2600

Posted by alex_79 on Sun Nov 18, 2018 6:45 AM

I played a few rounds. Judging from the scores posted so far I need to practice a lot!

Aardvark (Demo).png

Found no bug so far, apart for the already mentioned HS one. I really like the game. Beautiful graphics, interesting gameplay and precise controls.

 

P.S. I'd like to play this on real hardware too, any chance for a PAL(60) version?




#4138656 VCS/2600 Game Rarity by Number of Known Copies

Posted by alex_79 on Sun Oct 21, 2018 2:47 AM

The Magicard was aimed to computer and electronic hobbyists who also happened to own an Atari 2600, it wasn't a product for the general video game console market.
In fact it was advertised in magazines like "Popular Electronics" or "Byte"

 

Poptronics-1981-08-p64.jpg Poptronics-1981-08-p65.jpg

 

Byte_1981-05.jpg

 

People buying this were interested in its functionality and in the included manual, not the packaging.  They were building electronics projects published in magazines and buying kits (The MagiCard requires to build an additional circuit for the cassette interface to load and save programs and provides schematics and theory of operation for such interface in the manual).

The presence of a case and label was totally irrelevant, and a fancy artwork wouldn't have had the effect of making it look more "professional", but exactly the opposite. It wasn't a toy, and shouldn't have looked like one.




The Magicard allowed to inexpensively turn a 2600 console into an hobby computer similar to some of the single-board computers like the KIM-1, at least  in their basic configurations (BTW, a professional product. No case or label, just a bare board and docs).

 

Moreover, its manual was an invaluable source of information for everyone who wanted to write commercial 2600 games.
Check this post by Dan Oliver, for example

[...]
At that time I know companies were willing to buy stolen 2600 programming manuals for hundreds of thousands of dollars. But then Magicard comes out for $50 with what turned out to be a complete 2600 programming manual. I think every company that started making 2600 games at the time bought one copy of Magicard.
[...]

 

 

And this unclassified Ad from "Byte" magazine 04-1983:

Byte-1983-04.jpg



Video Life is a much more niche product than MagiCard (which already is a niche product!). It is something that would mostly interests mathematicians, and it was more interesting to program it on a computer (A reduced version could be coded on the Magicard, and it was in fact one of the example programs on the manual) than having it on a cartridge without the ability to modify the code.
I find reasonable and expected that its sales were just a (very) small fraction compared to Magicard.
MagiCard and VideoLife used the exact same pcb and parts. Just the code programmed in the eprom differs between the two. I see Video Life was a way to help selling the existing MagiCard parts, and it made sense producing it only because it didn't required investments for new hardware.


 

 




#4135344 Atari 2600 Heavy 6er issue

Posted by alex_79 on Tue Oct 16, 2018 11:52 PM

Joystick directions are connected to the RIOT (6532), not the TIA.




#4119198 First Homebrew Game

Posted by alex_79 on Sun Sep 23, 2018 10:29 AM

Since you have a supercharger, there's a simple way to find out if your TV supports PAL60: load a NTSC game in the supercharger and see if your TV can display it.

Since your Atari is PAL, the result will be a PAL60 Signal. The colors will be wrong, because the palette in PAL and NTSC 2600 consoles are different, but homebrew games labeled as "PAL60" have the colors adjusted to match PAL palette. (In fact, that's the only difference with the NTSC version)




#4118050 ROM/RAM Cartridge emulator - Interton VC4000

Posted by alex_79 on Fri Sep 21, 2018 9:56 AM

An eprom emulator can do the job. You just connect it in place of the eprom on the game board and you can upload from the pc without the hassle of multiple eprom erasing/programming cycles.
There are some old eprom programmers that also have that function, and with some patience you can find them quite cheaply (in the 50$-100$ range).

 

I have a promicron 2000 and successfully used its "eprom simulator" function to test games on several consoles for which I don't have flashcarts, including my Interton VC4000.
I only have an "invaders" cartridge and it doesn't have all the pins on the edge connector, so I'm currently limited to 2k games with no extra ram until I find a better donor cart or I get a PCB done (or I etch my own).
 




#4117975 Starpath Supercharger CD/WAV Files

Posted by alex_79 on Fri Sep 21, 2018 8:17 AM

No need to get the CD. The roms for all the original games are available (for example on Atarimania). You can convert them to wav using the "makewav" utility, or play them directly (without generating a file) out of the soundcard with "Playbin".

Attached File  makewav4.2.zip   55.6KB   25 downloads

Attached File  Playbin23.zip   39.22KB   27 downloads

The "makewav" archive contains sources that you can use to build a linux executable. Playbin is windows only, but works fine in Linux using wine.

I suggest to use an adapter when connecting the Supercharger to stereo equipment like a CD player or the PC soundcard, as the mono plug shorts the right channel to ground and not all devices might be designed to safely handle that.

I built mine using a short cable, an in-line female mono socket and a male stereo plug. Only the left channel and ground are connected between the two; the right channel of the plug is left disconnected.


 




#4115778 Fake/Repaired Promotional only Vader 2600?

Posted by alex_79 on Tue Sep 18, 2018 2:32 AM

The bezel with orange border is probably from a "Woody" console (or it has been painted), as in Vader models it was all black.
 




#4113875 Arkyology - New prototype discovered - Finished Game!

Posted by alex_79 on Sat Sep 15, 2018 4:10 AM

The "ship bounce" was happening because the INTIM timer value used was just barely straddling a 76-cycle interval between displays...was this intended?  Does it happen with the proto?  Or is it just an issue with Stella?

Is this happening during gameplay or only after transition from one screen to the other? I haven't yet managed to play this game, but I will gladly try this out in Stella and on real Hardware + CRT to see if there's any difference
 
Speaking of which... what about a PAL(60) conversion? Poor Noah seems to suffer severe seasickness on my PAL TV: he turned green!
 Arky-Mod(fix_v2).png
(This should also please the "purists": Noah was from Mesopotamia, so he had a PAL TV! icon_razz.gif)


#4113865 [Very odd scanlines problem!] Strange B&W effect in game

Posted by alex_79 on Sat Sep 15, 2018 3:45 AM

The framerate is not stable if you set the left difficulty switch to "A" position by pressing F5 (default in Stella is both difficulty set to "B").

 

Many PAL TVs will display in B/W if there's an odd number of scanlines and that's what you're seeing on your TV (it's the same on my CRT) .

 

Stella emulates this effect: go to "Options" > "Developer Settings", then select the "Video" tab and enable "PAL color-loss". Since this is an effect that only applies to PAL TVs, you must also tell Stella to run the game in PAL60 mode: you can cycle through the various modes with CTRL+F while playing the rom, or you can set it by selecting "Options" > "Game Properites" and change the "Format" in the "Display" TAB.

Once you do all these three steps (enable PAL color loss, set left difficulty to A and set Format to PAL60), you'll see the game in Stella behave like on your TV.
 




#4113531 CD4050 A/V mod on PAL atari 2600

Posted by alex_79 on Fri Sep 14, 2018 3:15 PM

Yeah, I had Stargate when I was little, and I really enjoyed the game, but I was gifted it as a cartridge only and I never knew anything about the controls from the second controller.

I had the manual, but it was in english only and I couldn't understand a word of it at the time (I'm only slightly better now...). I discovered the extra functions by chance, when my cousin pressed the button of the second joystick while I was playing...
 

I like how the controller port mod came out, as it's quite well hidden, but if you see it, it doesn't look out of place like a wart simply added on.

I agree, it looks like it has always been there. Good job!icon_thumbsup.gif




#4113509 CD4050 A/V mod on PAL atari 2600

Posted by alex_79 on Fri Sep 14, 2018 2:49 PM

The original jack briefly shorts the power supply to ground each time you insert or remove the plug, so that's another good reason to replace it.

 

Another mod I added which you can't see is a front 9 pin joystick connector hidden under the the lip of the console, a bit like how the 5200 and 7800 had theirs, but this port is connected to just the direction, action buttons and ground of the left controller. The other 3 pins I intend to connect to the action button, up and down of the second joystick port, so when I make my arcade stick, I can plug it in to this front port and have 4 action buttons for Stargate (Defender II), and the frontal port still be compatible with the standard Atari joystick at the same time, and still have the back ports for things like paddles.
 

Very clever! Stargate is one of the games I had as a kid, but actually I never used the second joystick: I only had two proline joysticks at the time and you can't easily press the button or move the stick on those unless you keep them in your hand...




#4113367 CD4050 A/V mod on PAL atari 2600

Posted by alex_79 on Fri Sep 14, 2018 11:21 AM

I appreciate the appreciation, thanks!icon_smile.gif

And thanks for posting pics of your mod. That's really well put together, I wish I could do such a nice and clean job! (there's a reason why I didn't posted pictures of my finished mod...icon_mrgreen.gif )
I like the use of the mini-din connector for all the audio and video signals (especially on the jr, where space is very limited). And, it seems that you also replaced the 3.5mm audio jack with a barrel connector for power. That's a good idea!