New Atari 5200 Prototypes

[Tempest]

Thanks to the generosity of John Hardie @cx2k I'm happy to release several new Atari 5200 prototypes.  All of these roms are slightly earlier versions, but I haven't been able to determine exactly what's different about most of them.  Many of them are dated only a few days earlier so the differences are most likely very small (cope optimizations, obscure bug fixes, etc.).  If anyone can tell what's different about these protos please let me know!

 

Choplifter 1-13-84 - Seems to be very close to the known 1-4-84 proto.  The only real differences I saw were the copyright on the splash screen says 1983 and there is no demo.  I also found out that the unknown Choplifter prototype I had that I assumed was the final is actually slightly different.  I'll attach it here as well.

 

Gremlins 5-15-84 - Dated only two days before the final (5-17-84), but has some different bytes here and there

 

Millipede 1-4-84 - An early version of Milllipede, but has some byte differences from the documented 1-5-84 version (http://www.atariprotos.com/5200/software/millipede/1584.htm)

 

Stargate 1-13-84 - This is an interesting proto. It's very close to the known 'final version' (1-5-84), but despite being dated over a week later it seems to actually be an earlier proto.  It has some differences on the options screen and is missing the copyright and demo. (http://www.atariprotos.com/5200/software/stargate/11384.htm)

 

I'm also attaching some of my prototypes which I believe have already been released, but are very close in date to the new protos.  Maybe they'll help people find some differences?

 

Gremlins 5-15-84.bin Millipede 1-4-84.bin Choplifter 1-13-84.bin Choplifter (Unknown).bin Stargate 1-13-84.bin Stargate 1-5-84.bin Choplifter 1-4-84.bin

[Kr0tki]

Some of your ROM images are overdumps. I've stripped the ROMs from unnecessary data and I'm attaching them below.

• Stargate 1-13-84 is a two-chip 16KB cartridge.
• Millipede 1-4-84 is a one-chip 16KB cartridge.
• Choplifter 1-4-84 is a two-chip 16KB cartridge.
• Choplifter 1-13-84 is a one-chip 16KB cartridge.

 

Some differences I've noticed:

• Comparing Choplifter 1-4-84 and Choplifter 1-13-84, most of the binary differences amount to switching from two-chip to one-chip cartridge during development. Basically, all ROM accesses to the $6000-$9FFF area needed to be changed to point to $8000-$BFFF instead. Other than that, there are only two other differences between the two:
  • When pressing Reset, 1-4-84 goes to the BIOS splash screen, while 1-13-84 goes to the title screen like the final version.
  • The CHOPLIFTER! title on the splash screen is off-center in 1-4-84, in 1-13-84 it is centered like in the final version. (Update your screenshot on the 1-13-84 page, please!)
  • And, as you noticed, there is leftover source code garbage in 1-13-84.
• Comparing the "unknown" Choplifter prototype and the final version, there are two differences I have noticed:
  • In the proto there is a little glitch on the top white bar above the points display - part of its left side is miscoloured. (Again, please fix your screenshots.)
  • The demo mode in the "unknown" contains a custom attract mode that cycles background colours (wait a minute or so), presumably for screen-saving. The final version does not implement any custom attract mode and just uses the standard one as implemented in the BIOS, which kicks in after about 9 minutes. Note that the "unknown" prototype does not disable the standard attract mode, so after 9 minutes it kicks in and starts colour-cycling the top frame of the screen independently.
  • The prototype (and the two earlier prototypes too) does not work with the two-port 5200 BIOS. They fixed compatibility in the final version.
• On Stargate 1-13-84, the game's title shows up for me on the splash screen, both in Altirra and in Atari800, same as the 1-5-84 prototype. Are you sure there wasn't some kind of a mixup?

Choplifter! (1984-01-04)(Atari)(proto).bin Choplifter! (1984-01-13)(Atari)(proto).bin Millipede (1984-01-04)(Atari)(proto).bin Stargate (1984-01-13)(Atari)(proto).bin

Edited May 8, 2023 by Kr0tki

[Tempest]

Thanks for fixing those dumps for me.  Makes it easier to run a binary compare on them.

 

I'll look at those Choplifter protos

 

For Stargate what I meant is that the copyright message doesn't appear on the bottom of the main title screen (the one with all the options).  The splash screen with the copyright message is still there (although it says 1983 instead of 1984).  But now that I look at the 1-5 proto I'm not seeing it on the main screen either.  I swear it was there!  Maybe I was looking at the 800 rom which does have it?  BTW I have no idea where this 800 rom came from!  Is it the same as the 5200 1-5 rom?

Stargate.rom

[Tempest]

@Kr0tki I updated my Choplifter pages.  Thank you for finding out all those changes, I never would have been able to find those on my own.  Let me know if you find anything else!

 

BTW here's a few Berzerk prototypes I've never been able to find the major changes in.  The 6/1 proto (152-06) even has two extra levels!  Oh and a Miner 2049er proto that tests differently but I'm 99% sure is the final...

 

 

Berzerk 152-06.bin Berzerk 212-08.bin Berzerk (8-3-83).bin

Miner Proto.bin

[Tempest]

Looked at the Millipede 1-4 rom and other than a few bytes here and there there is one section that has a small change that looks larger due to the code being slightly shifted.  I'm guessing whatever change was made isn't going to be easy to spot without examining the code.

 

@Kr0tki Is the Gremlins rom an overdump as well?

[Kr0tki]

I have disassembled the aforementioned section that's different between Millipede 1-4-84 and 1-5-84, and it is some code that sets up some RAM areas during cartridge initialization. I don't know the actual function of it. In 1-5-84 the order of instructions in this section has been modified, but no new functionality was added. I guess it was done do fix some bug, but I don't understand the details.

 

I don't know about the other single-byte differences between these two versions.

 

Gremlins is indeed an overdump, too - the cartridge contains one 8 KB ROM and one 16 KB ROM in a 32 KB PCB, so a proper ROM image without unnecessary data should contain only 24 KB of data. But emulators do not yet support 24 KB ROM images, so I decided to just leave it as it is, with the 8 KB padding at the beginning. So if you want to compare different versions of Gremlins, just ignore the differences in the first 8 KB.

 

There are other instances of this issue, both on the 5200 and the 8-bits - there exist cartridges that contain 2 KB+4 KB ROMs, 4 KB+8 KB ROMs, 8 KB+4 KB ROMs (technically a different case), or 4 KB+16 KB ROMs, there is even this SALT E00.01 cartridge that apparently contained two 2 KB ROMs but in a layout that effectively used the whole 16 KB address space of the cartridge. All these combinations of ROMs are not supported by emulators, so the ROM images that are shared online typically contain some padding blocks of empty or duplicate data added, to increase the image size to 8 or 16 KB.

Edited May 12, 2023 by Kr0tki

[Kr0tki]

On 5/8/2023 at 6:47 PM, Tempest said:

Oh and a Miner 2049er proto that tests differently but I'm 99% sure is the final...

It is 100% identical to the final version - once we consider that the final version ROM available here at AtariAge is an overdump and should be cut in half.

[Tempest]

4 hours ago, Kr0tki said:

Gremlins is indeed an overdump, too - the cartridge contains one 8 KB ROM and one 16 KB ROM in a 32 KB PCB, so a proper ROM image without unnecessary data should contain only 24 KB of data. But emulators do not yet support 24 KB ROM images, so I decided to just leave it as it is, with the 8 KB padding at the beginning. So if you want to compare different versions of Gremlins, just ignore the differences in the first 8 KB.

If that's true then the 5-15 Gremlins must be fairly different because it tests differently than the other one I have.  Here's the kicker though, I have no idea if the other one I have is the final or just 'close to' the final.  For whatever reason I can't get these Gremlins protos to properly compare.

Gremlins (5-15-84).bin Gremlins (fixed).bin

[Kr0tki]

First thing first, the Gremlins ROM hosted here at AtariAge is a bad dump with incorrect graphics during gameplay, as visible on the bottom screenshot here: there are incorrect blue pixels in the text PLAYER TWO and above the mogwai head in the bottom right corner of the screen. The correct ROM of Gremlins is available at Atarimania.

 

With that out of the way: The three available versions (your two protos and the version at Atarimania, assuming it is final) differ in binary comparison, but I don't know the actual differences in game. The only difference I have noticed is that the "Gremlins (fixed).bin" version uses a slightly brighter colour palette at the title screen and during gameplay. Considering that there is this "fade in" effect when a new level starts, this difference is probably a result of the fade-in loop doing one more step in the "fixed" proto than in the two other versions.

[Tempest]

2 hours ago, Kr0tki said:

First thing first, the Gremlins ROM hosted here at AtariAge is a bad dump with incorrect graphics during gameplay, as visible on the bottom screenshot here: there are incorrect blue pixels in the text PLAYER TWO and above the mogwai head in the bottom right corner of the screen. The correct ROM of Gremlins is available at Atarimania.

Huh, would you look at that.  I never noticed that before.

 

The Gremlins(fixed) is an old Gremlins proto I picked up years ago that I assumed was the final (I believe the final version dates to 5-17).  The 5-15 one is a new one that John Hardie @cx2k found.  If my undated one has a brighter palette on the title screen (boy is that subtle) than the 5-15 and the final 5-17 version I guess my undated one is older than the 5-15.  Just a guess anyway.

 

Good eye to see that difference in color.  Even side by side it's hard to see.