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TheMontezuma's Photo


Member Since 23 May 2011
OFFLINE Last Active Today, 1:48 AM

Posts I've Made

In Topic: SIO2BT

Sun Oct 14, 2018 3:49 PM

I have some updates about the SIO2BT app.


The new version 3.00 of the app was just released:

- it has improvements related to the file selection (a filter to narrow down the number of displayed matching files, useful when dealing with huge number of files)

- it does not have a Bluetooth MAC address database anymore and allows connections to any BT SPP devices (like HC-06) with names starting with "SIO2BT" or "ATARI"

- the app source code is released under GPL license: https://github.com/TheMontezuma/SIO2BT

- the apk file is also uploaded to the Github: https://github.com/T...3.00/Sio2Bt.apk


I would like to thank you guys again for your support over the last years.

Four years ago SIO2BT was submitted to the ABBUC contest and won the first price :)

And now I decided to release the source code and to remove MAC address database protection.


To be honest my decision was accelerated by a new Google security policy.

Starting 1 Nov 2018, there will be no updates allowed to the apps targeting older smartphones.

This means, the version 3.00 will probably be the last version available via Google Play.


I tested it on various Android devices:

- LG with Android 2.3

- Huawei with Android 4.0

- Nexus 5 with Android 6.0.1

- Pixel XL with Android 9

and I hope it will continue to work properly on your Android phones/tablets.


I also recommend a great Android port of the AspeQt (with Bluetooth support) from Greblus:



and the PC RespeQt software:



Have fun!



Although you can use now any BT transceiver with the SIO2BT app, I still have a limited number of devices in the 3D printed cases.

In Topic: Atari Rev B PAL Rom file

Thu Aug 9, 2018 2:37 AM

Thank you bery much for a comprehensive explanation :)

The reason I asked is I wondered if it is better to leave the checksum bytes as they are when patching the OS B NTSC or to calculate new checksums.

I understand that it does not matter that much. Having valid checksums may even have negative impact if there is any software relying on the wrong checksum values.


Are you aware of any software (other than SALT) checking OS checksums and refusing to work if the OS was not identified (I mean any Atari OS, not particularly B NTSC) ?

In Topic: Atari Rev B PAL Rom file

Wed Aug 8, 2018 2:20 AM

Things get complicated however, when a OS B is present.


SALT checks the values at $fff8 and $fff9. If they equal $f3 and $e6 (as in OS B NTSC), then it assumes that the checksum equals $5a02 and then calculates a sum of all bytes from $f000-$ffff, including the bytes at $fff8 and $fff9.
For the Low ROM it's similar: If SALT finds $00 at both $e40f and $e41f (as in OS B NTSC), then it sets the checksum to $ec9f and then calculates a sum of all bytes from $e000-$efff.


This is interesting :-o


What is the reason for the strange checksum values in the original OS B NTSC?

Did Atari produced ROMs with wrongly calculated checksums and they decided to sell the computers equipped with these ROMs?

If I'm not mistaken, the checksums for OS B NTSC (if calculated like for the OS A) should be:


Low ROM checksum = $EC9F (and not $0000)

High ROM checksum = $5829 (and not $E6F3)


Is there no selftest / selfcheck in the OS B NTSC?

Does a SALT diag cartridge handle that mistake and properly detects the OS B NTSC?

In Topic: 45+ Years to Sunnyvale, California: a pilgrim's journey...

Tue Jun 26, 2018 6:07 AM

And one more:


Attached File  1265 Borregas Ave.jpg   128.71KB   15 downloads


1265 Borregas Ave


It is sad to see this nice office building staying empty.

If you look closer, you will see one of many new Google's fancy glass offices (in the background).

It seems that 30 years old buildlings do not match modern standards any more and are too small for the giants...

In Topic: 45+ Years to Sunnyvale, California: a pilgrim's journey...

Mon Jun 25, 2018 7:11 PM

Dreams come sometimes true :)


Attached File  1196 Borregas Ave.jpg   255.71KB   19 downloads


1196 Borregas Ave today