Atari EPG jr reverse engineer

[tin]

Aye, that's all it does

[curtjr4]

It's great to see that you are working on modes C and P Like Arix said, I know you will be able to do it I have faith in you lol.

[AriX]

I'm not massively clear on the data format as yet...but here are some things I do know.

First bit is
55 AA (some training)
41 (come code that means start I think)
2A (a * which means all EPGS perform this command - all or part of the serial number can go here for individual addressing of each or groups of EPG boxes)
00 (a zero)
94 (a checksum - note if you change the serial number the checksum needs to be worked out again).

Hi tin,

Just a question - how does the serial number checksum work? What number should it start with in order to calculate the correct checksum? I'm working on the data feed server and I'd love to be able to address boxes individually. I'm thinking we should reassign the serial numbers to ones that make sense to us, since we can't figure out exactly how the UVSG select code assignment worked.

[tin]

Checksum starts set to $BE, and then each letter of the serial number you use is XORed on top of each other. Terminate the serial number with a 00 (also included in the checksum. In the example with the *, the checksum is $BE xor $2A xor $00 = checksum

At least that's what I think it is. If not, then please let me know I'll take another look at the code.

[curtjr4]

Hmm. So how would I put that into the monitor? I guess I just dont get it I guess when I looked back at previous pages lol.

So, did you get somewhere with modes C and P? Or are those still a mystery?

[AriX]

Hmm. So how would I put that into the monitor? I guess I just dont get it I guess when I looked back at previous pages lol.

So, did you get somewhere with modes C and P? Or are those still a mystery?

Huh? How do you put what in the monitor? What he was last posting about? You don't need to worry about that for now, it's just for the data feed server I'm writing.

And I assume when tin gets somewhere with listings, he will tell us... It's very complicated, so just hang tight and I'm sure he'll figure it out soon

[Bolt96]

Yeah. All this is just amazing. Thank you AriX, tin, swest77, and everyone else who has helped with this awesome project. It seems like we're making great progress!

[tin]

P and C will indeed be a while, sorry

[AriX]

So today I finally got around to messing with the source code of Atari800 and I got it to accept serial input without using the monitor (not through the actual SIO interface, but by writing to 3800 and 00c8). I will write some code to make it work as a client to the UVSG Satellite server I'm working on and release it

[tin]

Sounds very cool