|Wiring of 96 LEDs for the left side of console light display|
These are placed in 1:1 scale to an IBM 1130 display - the board you see is 4" by 10", the left side of the 1130 panel lights encompass a 5" by 10" space, adding in the right side produces the 20" x 5" black display that lights to indicate the contents or status of key parts of the machine. This board will sit inside the display panel box, with 1/2" clearance to the top and bottom, fronted by a smoked plexiglas plate that will recreate the lettering and cutout numerals that are lit by the LEDs in each position.
|Left side of light panel - contents of six registers|
The six registers, from top to bottom, are the Instruction Address, Storage Address, Storage Buffer, Arithmetic Factor, Accumulator, and Accumulator Extension Registers, each 16 bits wide.
|IBM 1130 at National Museum of Computing, Milton Keynes, England, UK|
Our light panel represents the left half of the black rectangle you can see to the right of the red 'emergency pull" switch.
|LED driver boards|
|Switch/Button input multiplexor board|
|Input debouncer board|
The 16 toggle switches, called the Console Entry Switches, are separately multiplexed by an MCP23S17 chip which is very similar to the MCP23017 but uses the SPI protocol, a four wire serial link, rather than the I2C protocol of the other chip. Debouncing is currently done in the FPGA hardware but will be handled by MC14490 chips in the next version of the board (not pictured here).
Together, these boards allow 240 input and output devices (LEDs, buttons, and switches) to be connected using only 9 wires into the FPGA.