IKBD on Atari 520st (18 pin connector)

News, questions and bugs reports about CosmosEx by Jookie. Now we have a Raspberry Pi in our machines!

Moderators: Jookie, Moderator Team

StEeLz
Retro freak
Retro freak
Posts: 11
Joined: Wed Jan 20, 2016 3:57 am

IKBD on Atari 520st (18 pin connector)

Postby StEeLz » Wed Apr 20, 2016 9:22 pm

Hi everyone!

I have everything up and running on my Atari 520st (early model, external Floppy).
I know the disclaimers said it wouldn't work because the early TOS 1.00 and the buggy filesystem handling BUT it works like a charm, even better if you are loading SELTOS and loading a TOS 1.04 or 2.06 on RAM (resident).

However, the only issue I found was with the keyboard connector, the ST has an 18 pin connector as the Joystick signals are routed to the keyboard chip as well.

I was wondering if any of you ever tried to mod/adapt the IKBD sandwich-type connector on the 520st.

I've attached a picture of the 520st motherboard connector :
MotherBoard.jpg


As well as some pinout information found on the excellent "BitBook" resource by Karl N. H. Meyland :
BitBook.PNG


Any idea, let me know! If none, I'll try a few things and keep you posted!

Baptiste
You do not have the required permissions to view the files attached to this post.

User avatar
Jookie
Hardware Guru
Hardware Guru
Posts: 1245
Joined: Wed Feb 04, 2004 6:54 pm
Location: Kosice, Slovakia
Contact:

Re: IKBD on Atari 520st (18 pin connector)

Postby Jookie » Thu Apr 21, 2016 9:56 am

StEeLz wrote:However, the only issue I found was with the keyboard connector, the ST has an 18 pin connector as the Joystick signals are routed to the keyboard chip as well.

I was wondering if any of you ever tried to mod/adapt the IKBD sandwich-type connector on the 520st.


Hello, I will take a look at that, I will let you know.

Jookie

User avatar
Bama
Captain Atari
Captain Atari
Posts: 169
Joined: Sat Feb 28, 2015 1:25 pm

Re: IKBD on Atari 520st (18 pin connector)

Postby Bama » Thu Apr 21, 2016 11:25 pm

Hi Baptiste,

Please check my answer with someone with more expertise before connecting things. I had to create an IKBD connection for my STacy because it does NOT have a compatible keyboard connector either. I'm guessing you may need to do something similar.

When I look at the 520ST and the MegaST schematics the Keyboard jumper (J12 on the 520 and J4 on the Mega) both are 18 pins and the descriptions appears similar.

The Cosmos Ex requires four lines:
1) keyboard transmit original ( keyb tx orig )
2) keyboard transmit from cosmos ( keyb tx )
3) keyboard receive ( keyb rx )
4) ground ( GND )

So the IKBD injector for the CE "injects the data from the CE by re-routing the "keyboard transmit original" from the ST and sends it to the CE, then "keyboard transmit cosmos" returns the signal to the ST.

I am trying to think of the the most non-permanent changes you can make and still "inject" the CE signal.

1) On my STacy, I removed the IKBD IC (6301 - which is also on the 1040ST and might be universal) from its socket, pin 11 bent outward and soldered to wire and then IC was re-socketed) = keyb tx orig (TX signal going from keyboard, which is sent to CE for processing). My hope is you have the same IC socketed on the underside of you keyboard.

2) Pin 15 of Header Socket labelled J12 is keyb tx (TX signal going from CE to ST, which contains original keyboard data + injected data) is where I believe you need to return the signal to your 520ST.

3) Pin 14 of Header Socket labelled J12 is keyb rx (RX signal going from ST back to keyboard and to CE)

4) Pin 1 of Header Socket labelled J12 is GND.

I have attached the cropped schematic from the 520ST highlighting the pins on J12. And a picture of my STacy IC 6301 with the soldered wire to pin 11.

Please check with an expert. I am a novice!!!! I hope this helps though.
You do not have the required permissions to view the files attached to this post.
:-)
BAMA


Social Media

     

Return to “CosmosEx”

Who is online

Users browsing this forum: No registered users and 1 guest