I had added a simple capability to the System Source 1130 system, just as I had designed it for mine and for The National Museum of Computing in the UK. It has a bank of relays wired to the console entry switches and several of the console pushbuttons. This allows the user to rapidly load any content into core memory without the time consuming effort of manually flipping switches and pushing buttons.
In order to load a word into memory at some location, one first sets up the load address by flipping the 16 console entry switches to the desired address. The Mode rotary switch is set to Load and the Load IAR button is pushed. This sets the Storage Address Register to the intended address.
The user then sets the 16 console entry switches to the first data word to be entered, then pushes the Start button to load it into storage. The memory address is automatically incremented to the next sequential address, so that one can load subsequent data words by 'only' switching sixteen console entry switches and then pushing Start, for each one.
Loading a very long program into memory is tedious and error prone using the physical switches and buttons. This modification installs an Arduino that drives relay boards to electronically set the console entry switches and to electronically push Load IAR or Start. The Arduino is connected via USB to a serial terminal, usually a laptop, where an ASCII file can be transmitted line by line. The file format uses characters like @ to designate setting the memory address otherwise the characters are the hex value to set in the console entry switches.
Thus a very long set of words to put in memory is typed into a file as sets of four hex digits with optional prefix characters. That file is opened by the serial terminal program which looks for the prompt character coming from the Arduino before sending each line to be loaded into the 1130.
The implementation required adding sixteen wires to the console entry switches, which are on the inside of the front panel of the 1053 console typewriter. The normal cable from that panel runs down into the 1130 logic gates but has some spare length to allow the panel to be moved from its fixed spot. This is because the panel is attached to the front of the console typewriter itself, so then whenever the typewriter must be removed for service, cumbersome disassembly is needed.
The typewriter is lifted off its normal location but is limited by the length of the console entry switch cable. The typewriter is turned on its side and screws are removed to detach the front panel with the switches. This allows the typewriter to mover over a bit further, but the typewriter is cabled into the 1130 with three SMS cards attached deep in the bowels. Two are the signals for the typewriter and one is the power for the device. These must be detached after unsrewing and swinging things around underneath, then snaked up to finally be able to move the typewriter to some remote workbench for service.
When I added the Arduino based loader, I added my own wires to the back of the console entry switch panel. These were wired directly to relay boards screwed down between the keyboard and the typewriter front panel, under the tabletop. Thus, the front panel was further restricted, not just by the standard cable down to the logic gates but also by my new wires which were shorter. This made the cumbersome juggling even harder.
I therefore inserted a set of connectors so that my wires come out of the panel to a connector, then the wires from the relay boards run to the other connector. This allows separation of the wires so that the only anchor on movement of the front panel is the length of the standard IBM cable down to the logic gates.
No comments:
Post a Comment