Monday, July 13, 2020

First connection between Hercules (370 MVS 3.8 emulator) and the 3178 terminal using 3174 replacement

STARTING HERCULES WITH MVS 3.8J WAITING FOR THE CONSOLE

Volker's turnkey MVS 3.8J system with Hercules was the basis for my test today. I modified the configuration file to remove the other 3270 terminals, leaving only the main console at x010 which I would connect with on port 3270. 

CONNECTING WITH THE 3174 SUBSTITUTE AND TN3270

I fired up the oec code pointing it at localhost and port 3270 where it established a session connection. I saw the confirmatory text on my physical 3178 terminal. Further, I could move the cursor around with the arrow keys. However, the NewLine key was not working properly. Not sure if this is an issue since I had more serious challenges ahead.

IPL ATTEMPT ON MVS

This configuration of MVS has the sysres volume on drive x148 thus I did an IPL from it to begin the process of bringing up MVS. Very soon after it began, when the boot time code began to write to the console, I received an index out of range error in the oec code which crashed. 

This appears as if it were trying to write beyond the end of the buffer which in my case is a 24 line by 80 character terminal thus 1920 characters. I need to instrument the code a bit more in order to discover exactly what is happening and why. 

There is a decent chance that this is caused by some misconfiguration of the Hercules/MVS environment leading to the IPL code writing bad data streams to oec. I need to play with the system a bit using ordinary tn3270 client software on my laptop in order to ensure that my setup is correct. 


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