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About mozzwald

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    Peoria, IL
  1. The fix is up. https://github.com/mozzwald/Zimodem/tree/atari
  2. I found the problem. DTR code was causing the connection to break during disk activity. Removing that seems to be working. I sent and received a small txt file with xmodem. I will clean up the code and push changes to github tomorrow.
  3. The problem is that when connected to a bbs, any SIO activity causes the connection to die and the modem is put back in AT command mode. There is a noticeable delay when the system tries to read from floppy. Then, I assume the connection is lost and the system reads from the disk just fine. In AT command mode, SIO activity is working fine.
  4. I don't have access to the files area so I installed mystic bbs on a linux box at home. I am unable to send or receive files. When connected to a server, the disk access causes the connection to be dropped and the modem is put back in command mode. Looks like more work to be done in Zimodem code 🥴
  5. Just a few more notes about the setup... You can flash the nodemcu with the usb port as normal. When Zimodem starts up, it switches the TX & RX lines from the default GPIO 1 & 3 to GPIO 15 & 13. This prevents the bootloader messages from being spewed out to the atari at powerup. This also means, you will not see anything on a serial terminal on the computer when connected with the usb port (also the command & motor lines would need to be pulled low for transmission to occur). The 1k resistor on GPIO 15 is required to prevent the nodemcu bootloader from trying to boot from SD card at powerup. The pull down on Atari side Motor Control was needed as the level shifter wasn't pulled down enough to register a low reading. Can anyone recommend a bbs that has files available for download with Xmodem? I want to see if it will work with bobterm.
  6. Definitely not using i2c on the nodemcu. Not really sure what was causing the problem. I got garbage on both the atari and pc when testing with a usb to uart adapter. Also tried 2 different boards to make sure it wasn't a bad one.
  7. I tried a similar level shifter and it didn't work (TXS0108) so I got the fet based one instead.
  8. I've been fiddling around with my nodemcu (esp8266) board, Zimodem firmware and the atari and have been successful with using the modem while allowing the atari to still use the sio bus with minimal parts. I have a simple fet based level shifter (wiring diagram below, amazon part) that adds the motor control and command lines to nodemcu inputs. When either line is asserted, the Zimodem firmware allows other devices to communicate on the bus and ignores the transmission. The modified firmware adds a new Flow Control type (FCT_AMTRCTL) which must be enabled for it to work. If you wish to flash the firmware to a previously used zimodem/esp board you should format the SPIFFS before flashing so that the new flow control will be selected by default, otherwise you will have issues with it not communicating as it will be set for some other flow control scheme (this issue bit me a couple times during testing). The modified Zimodem (v3.5) firmware is in my github (atari branch) at https://github.com/mozzwald/Zimodem/tree/atari
  9. http://www.maxkeyboard.com/ansi-layout-custom-color-cherry-mx-keycap-set.html I *think* it can be done with the ANSI 87 Key Layout (6.50x Spacebar and Top Printed Keys) but I haven't completely verified it yet. Depending on available extra keys, might need to use the 104 layout. Yes, I had that idea also and should be possible to 3d print something. Can add some screw holes to the keyboard pcb for attachment of the bezel
  10. I've been looking into making a new keyboard for the 400 and picked up some sample switches and keys for experimentation. Regular cherry keys are quite tall but the low profile kailh brand keys are a bit shorter. To use the Kailh switches with Cherry keycaps you need an adapter which I 3D printed. Cherry keycaps are 18mm square and are meant to be on 19.05mm centers which does not allow the original 400 layout to be used. I came up with this layout. Any recommendations are welcome. The keycap samples I got are from MaxKeyboard. They seem a bit thin but I think they would be alright to use. It looks like you can get a complete set of custom printed keycaps for less than $50. This would allow for custom legends on the keycaps. I had one key printed as a sample and it looks good. The brown, orange and yellow keys don't match the original 400 colors but I think would look alright. I also made this 3D printed chicklet style key that fits the Kaihl switches. It's only 16mm square and I think would be possible to get the original A400 layout. Problem is making the legends on the keys. I had the idea to make an indent on the top of the keycap and have custom cut stickers with the legend to put in them. Then perhaps clear coat it for protection. This path seems like the most work and I'm not really sure how the sticker idea would hold up over time. But, this is probably the only way to keep the original layout (other than having expensive custom injection molded ones made).
  11. These low profile Cherry MX keys might be an option for a new replacement keyboard: https://www.cherrymx.de/en/mx-low-profile/mx-low-profile-red.html Not sure if keycaps are available for them specifically. Edit: Just found these (different brand) keys and keycaps: https://novelkeys.xyz/products/kailh-low-profile-switches https://novelkeys.xyz/collections/keycaps/products/kailh-low-profile-keycaps-with-legends
  12. Could you connect the motor line to the esp and modify the modem firmware (on esp) to buffer data when the Atari SIO is busy (motor line asserted)?
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