- has mechanical interposer that forbids more than one key to be depressed at once
- keys latch down and are released by a solenoid, thus the keyboard is 'unlocked' by XIO
- all lamps work, so I should be able to interface the photocells that read the various key codes
|Keyboard mechanism I will adapt as 1130 keyboard|
I did some rough work to validate the voltage for the lamps and solenoid - lamps seem to work
well at 12V, distributed in series across the ten bulbs that illuminate the 10 photocells. The solenoid works cleanly at 24V, which is reasonable in concert with the 12V lighting circuit (which would be center tapped from a power supply producing +12V and -12V to yield 24 across the solenoid).
|Lamps visible at bottom, interrupted by keys to encode character|
|Key levers that latch down and interrupt selected light beams|
|Keyboard as it is now|
|Actual keyboard on an IBM 1130 for reference|
|Planned changes to keyboard|
|How printer width might distort the replica|
|What a real 1130 looks like, for comparison|
|Concept of coloring to minimize distortion from larger printer cover|
I have already removed the end keycaps that are superfluous and relocated one blue keycap over to its new position as the Int Req key.
|Superfluous keys removed on keyboard mechanism|
|'Aux Dup' key shows blue original color and recolored top|
If I had to change any key to stop it from participating in the mechanical locking (latching down until restored), I would only have to snip off the end of the keylever, as you can see in the closeup where the 'Alpha' key is so modified permitting it to be activated even when the remaining keys are latched.
|Lever directly under centered blue key 'Alpha' has tab cut off so it wont latch|
Certain of the keys are converted into separate signals for the 1130 adapter, among them are Erase Fld, EOF, Int Req, Space, Backspace, Numeric and KB Rest. Essentially, the blue colored keys get this special treatment, although backspace is an exception, colored grey but strobing its own signal rather than a data pattern. The others will activate values on a set of data lines (12, 11, 0, 1 - 9) except for the numeric, which simply toggles a state to determine the mapping of key to the data line values. Since the IBM keyboard is a leveraged part from an 029 keypunch, it emits hollerith code (e.g. A is 12 + 1 signals, S is 0 + 2 signal, digit 4 is 4 signal). The keyboard I am converting produces a modified version of hollerith, but the translation is straightforward for most keys.