I created a Buffer class that maintains a 2000 character buffer. My code in terminal now writes to the buffer object for insertion in that shadow buffer, with the buffer object also writing a copy through to the regen buffer inside the 3178 terminal.
Whenever data is written to the buffer object, but not by key press actions, I run a method that builds a list of tuples defining the fields found in the buffer. This is done by scanning the buffer for attributes. These field tuples also indicate whether fields are protected, numeric and when their contents were modified by key presses after it was written by the mainframe (or my fixed code in the terminal script).
The list of fields helps in implementing the TAB, BACKTAB, HOME, ER INP and ERASE EOF keys correctly, as I can locate the unprotected fields for movement and erasure.
OPERATOR INFORMATION AREA (STATUS LINE)
The bottom line on the screen is not accessible by the application programmer or mainframe. It is used by the control unit (CU) such as the IBM 3174 to signal important information about the state of the terminal and its interaction with the mainframe.
When the terminal is considered busy or locked due to operator error, symbols appear in columns 9 to 17. I implement these to display the symbols for 'key not allowed in this cursor location', 'this location is numeric only' and 'lengthy operation underway, please wait'.
In columns 37 to 41, the state of the terminal is displayed. The first column will have a symbol to indicate that the shift key or lock is engaged. The next column contains a symbol to show that the terminal is in insert rather than regular mode. The final columns show the characters NUM when the field is numeric only.
I modified my terminal program so that it correctly displays the shift, insert and numeric state, as well as displaying the lock and busy conditions.
A COMPLEXITY TO HANDLE
I found some of my logic falling apart because these buffers are circular. That is, just after cell location 1999 (line 24, column 80) we wrap around to cell location 80 (line 1, column 1). Calculating lengths of fields and matching when the cursor is in a field fails in the last field since it has to wrap around.
Quite a bit of the added functionality worked well, but I found a list of other defects to address. I will keep going on this effort because I am still waiting for Andrew Kay to produce a version of oec that makes use of my keyboard and I am still waiting for my color 3179 terminal.
Fedex sent me the alert that the package was due to be delivered on June 27 by 9PM. In the early evening of that day, they changed the projection to June 28th (Sunday). I was heartened to see that it was marked as onboard the delivery truck on Sunday morning. However, suddenly in the early evening of Sunday, the status went to "Pending, no delivery date set".
Today, Monday the 29th, I received another message claiming it would be delivered today by 9PM and once again the box was reported as onboard the truck. And, again, in the early evening the status changed to "Pending, no delivery date set". I placed a WTF call to Fedex.
Their automated systems insisted it was on the truck and coming today. I asked for an agent to show him how it was two days in a row of sham "on the truck" followed by "Pending" but he insisted that it was going to come tonight. He offered to have me call back tomorrow if it once again didn't arrive and they would then, and only then, call their third rate Fedex Home operation that was actually supposed to delivery it, to seek answers.
It didn't arrive tonight. The service commitment date was June 27th. It has sat in the local area since that time, sometimes pretending to be onboard a truck. Tomorrow morning I firmly expect to receive another cheery promise that it will be delivered and another baseless assertion that it is onboard the truck for delivery. And I know that when I call Fedex, they will contact Fedex Hopeless and be told that . . . it is on the truck.
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