Tuesday, June 28, 2022

Prepared Console/Keyboard test diagnostic to be ready as I restore the 1053

USING IBM 1130 SIMULATOR TO LOAD THE DIAGNOSTIC AND CREATE DUMP FILE

The diagnostic program that tests the keyboard and 1053 Console Printer (typewriter) must run under the control of the Diagnostic Monitor program. That monitor supports loading and running multiple of the device tests either sequentially or in parallel. In turn, the monitor must be loaded into core by the Relocatable Loader program.

I therefore stacked the binary decks into the virtual 1442 card reader - Relocatable Loader, Diagnostic Monitor, Keyboard/Printer Diagnostic and a blank card at the end. Booting this with CES switch 15 set on causes the code to stop prior to beginning execution of any diagnostic routines (in this case the keyboard and printer code). 

With the card deck loaded via Program Load button, it was ready for me to ask it to begin by reading the Console/Keyboard switch. I then created a text dump file from the simulator with the contents of the 8K words of core on the machine. That file is the input to my Memory Load Tool on the physical 1130 system, allowing me to start up the diagnostic from this point on the actual machine. 

UNABLE TO FULLY TEST DIAGNOSTIC ON SIMULATOR - MISSING CAPABILITY

The IBM 1130 has a switch on the operator panel to the right of the keyboard which has two positions - Console and Keyboard. This switch setting is recorded by bit 3 of the Device Status Word for the keyboard and console printer device, but otherwise has no impact on the system. 

The intent was to have software read this switch setting and based on that, either request typed commands or read the state of the 16 Console Entry Switches (CES) on the front face of the 1053 Console Printer. The CES switches can be read regardless of the position of this switch, making the switch an advisory input to a program guiding where that software checks for data.

The excellent IBM 1130 Simulator, written by Brian Knittel atop the Simh simulator framework, is quite comprehensive except in this regard. It does not implement that console/keyboard switch and instead reports the state of the switch as 'keyboard' when the device status is interrogated. 

This causes a problem due to the design of the console printer/keyboard diagnostic program. That program looks at the switch to determine whether we will jump directly to the keyboard test or perform the typewriter test first. The default position reported by the simulator causes the diagnostic to jump directly to the keyboard routine.

This routine will echo keypresses as typed characters on the console printer - endlessly until the switch is flipped to the 'console' position. Since I can't flip the switch with the simulator, we will never end the echo loop. 

The physical 1130 has a working switch and thus I will be able to have it on the 'console' setting to run all the tests I want. 

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