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RS232 over the joystick port


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#1 jrhodes OFFLINE  

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Posted Mon Jul 16, 2018 11:15 PM

I remember hearing that the TI's joystick port can be used as a rs232 port.

The person writing the article even transmitted a small amount of data over it, if i recall correct.

Unfortunately i can not seem to find that article right now.

Any one know the article in question and where to find it?



#2 JB OFFLINE  

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Posted Mon Jul 16, 2018 11:40 PM

http://www.mainbyte....lk/joytalk.html

#3 sparkdrummer OFFLINE  

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Posted Tue Jul 17, 2018 2:50 AM

Attached File  SSSD.dsk   90KB   8 downloads

 

Here is the source and object code for this device.


Edited by sparkdrummer, Tue Jul 17, 2018 2:50 AM.


#4 Vorticon OFFLINE  

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Posted Tue Jul 17, 2018 5:53 AM

Totally forgotten about this project. Has anyone ever built it?



#5 Shift838 OFFLINE  

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Posted Tue Jul 17, 2018 8:01 AM

Totally forgotten about this project. Has anyone ever built it?

 

I did not build it but I came by one some years ago.  Once I identified what it was I found someone that was interested in having it so I sent it to them.  He said it worked.  But it will not work with the standard terminal programs out there since it uses the joystick port. 



#6 Tursi OFFLINE  

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Posted Tue Jul 17, 2018 4:33 PM

We talk about it every couple of years. I built one and used it as my printer interface for about a year back in the day. :)
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#7 TheBF OFFLINE  

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Posted Wed Jul 18, 2018 4:40 AM

What baud rate can you get out it Tursi?

 

B



#8 RXB OFFLINE  

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Posted Wed Jul 18, 2018 10:34 AM

Joyport was much faster then the RS232 card for top performance.



#9 TheBF OFFLINE  

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Posted Wed Jul 18, 2018 7:46 PM

It  looks like the TMS9919 can get to 19,200 BPS and maybe even 38.4Kbps.

 

At that speed the CPU could barely keep up with the data while receiving a continuos stream, I should think.

 

I you added the overhead of reading bits on the 9901 with the 9900 CPU, how does it manage to do it faster?

 

I am amazed.   

 

Side question, what is the effective BPS rate of the Cassette save/load system?



#10 RXB OFFLINE  

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Posted Wed Jul 18, 2018 8:33 PM

It  looks like the TMS9919 can get to 19,200 BPS and maybe even 38.4Kbps.

 

At that speed the CPU could barely keep up with the data while receiving a continuos stream, I should think.

 

I you added the overhead of reading bits on the 9901 with the 9900 CPU, how does it manage to do it faster?

 

I am amazed.   

 

Side question, what is the effective BPS rate of the Cassette save/load system?

Hmm you put RAM on the 16 bit bus, so this smokes the RS232 performance.



#11 InsaneMultitasker OFFLINE  

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Posted Wed Jul 18, 2018 8:42 PM

Joyport was much faster then the RS232 card for top performance.

What is this statement based on?



#12 Tursi OFFLINE  

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Posted Wed Jul 18, 2018 8:53 PM

What baud rate can you get out it Tursi?


It ran through subroutine calls in MiniMemory, and basically toggled the joystick select lines. It was output-only, no hardware for data input (except it supported one or two of the printer status signals). I only ran it at 1200bps, I don't remember what it could get to (but the article is linked above ;) ).

#13 RXB OFFLINE  

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Posted Thu Jul 19, 2018 2:36 AM

Second article on PDF says (110 to 19200 baud) but I do remember someone had mods that got as high as 38400 baud and I think it was in Micropendium.



#14 mizapf OFFLINE  

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Posted Thu Jul 19, 2018 5:43 AM

Could the joystick port be turned into a I²C? I guess the power is again the main problem here.



#15 Stuart OFFLINE  

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Posted Thu Jul 19, 2018 6:12 AM

Could the joystick port be turned into a I²C? I guess the power is again the main problem here.

 

http://www.stuartcon...m#i2c_interface



#16 RXB OFFLINE  

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Posted Thu Jul 19, 2018 12:34 PM

Quote: "Cortex BASIC should also work as that includes instructions to control the CRU interface."

 

RXB has CALL IO too, that has been demoed on the Weather Station interface and other devices.






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