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atrax27407

Beta TI RS232 DSR available

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I currently have a beta version of the TI RS232 available. This version auto detects the clock speed (instead of using the value in the console ROMs) from 2.5 Mhz to 6.0 Mhz. It then branches to the appropriate baud rate table. It also adds additional high-speed baud rates. The available baud rates are: 110, 300, 600, 1200, 2400, 4800, 9600, 19.2K, and 38.4K BPS. I can supply the EPROM for $7 shipped.

 

Warning: This mod requires the replacement of the standard DSR on the board. If you are not adept at desoldering chips, I would not recommend trying this project. For best results, remove the standard DSR and solder a socket in its place before inserting the chip. If you are interested, please send me a PM.

Edited by atrax27407
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57 minutes ago, atrax27407 said:

I currently have a beta version of the TI RS232 available. This version auto detects the clock speed (instead of using the value in the console ROMs) from 2.5 Mhz to 6.0 Mhz. It then branches to the appropriate baud rate table. It also adds additional high-speed baud rates. The available baud rates are: 110, 300, 600, 1200, 2400, 4800, 9600, 19.2K, and 38.4K BPS. I can supply the EPROM for $7 shipped.

 

Warning: This mod requires the replacement of the standard DSR on the board. If you are not adept at desoldering chips, I would not recommend trying this project. For best results, remove the standard DSR and solder a socket in its place before inserting the chip. If you are interested, please send me a PM.

That is awesome. Would you share how you auto-detect the clock speed?

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OK - Here is the binary for those who want it. For those of you who are unable to burn their own EPROM, contact me by PM and I can burn you a copy and ship it for $7. 

ti_rs232hs.bin

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Neat mod for the RS-232, but I'm kind of curious, how many people out there have actually modified their systems clock speed?  Due to unforeseen incompatibilities, that is one mod I've never considered doing.

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Can you give some details on how you tackled this project?

Did you start from source (is the RS232 source available?) or did you do a disassembly and started from there?

 

Either way, great work!

 

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Thierry Nouspikel has both the RS232 source code and his patch on his website (the itself patch can be a bit difficult to find). The patch is basically in two sections - one part with the interrupt handling code and the other with the clock/baudrate code. I divided the patch, assembled the clock/baud rate portion and separately the entire patch together (I now had three files - RS232, clock/baudrate, and complete patch). I used the RAG Linker to create two files - one with just the clock/baudrate mod and RS232 code and the other with the whole patch and the RS232 code. Then, I removed the first 6 bytes of the both linked files with a hex editor (to remove information created by the Linker) so the file had the correct >AA01 recognition byte as the first byte. I then searched the file for the hex string containing the code for <DEL> and replaced it with the code for the true backspace and replaced it. The end result were the .bin files as I posted previously. Not difficult but just a bit tedious. 

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4 hours ago, atrax27407 said:

The patch is basically in two sections - one part with the interrupt handling code and the other with the clock/baudrate code. The end result were the .bin files as I posted previously. Not difficult but just a bit tedious.

Thanks for explaining why there's two files ... and more importantly, thank you for your tireless work🥳

Is this compatible with Fred's Kall HDX mod for the cards I've modified or is this for an unmodified PHP1220?

 

Doug

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On 8/3/2019 at 11:10 AM, atrax27407 said:

Unmodified - it is a direct DSR drop-in.

kinda, you still have to yank the rom and put in a socket

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The first one has the auto-clock speed detect and increased baud rates, The second also includes user-defined interrupt handling as well as a true backspace instead of <DEL>.

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