Building the console hardware prototypes

Here is the wiring for half of the console lights panel for the 1130 replica - these are the lights that display the contents of IAR, SAR, SBR, ACC, EXT and AFR registers, bits 0 to 15.

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

 Prototype boards implementing a chain of three MAX7219 chips that will drive 192 LEDs based on data sent over a three wire serial protocol link from the recreated 1130 FPGA board. This board operates at 5V and has a level shifting 74HCT00 chip to permit it to operate with signals from the FPGA which are based on 3.3V logic levels. 

Switch/Button input multiplexor board

 The board shown above will take 32 button or switch contacts and multiplex them over a two wire I2C serial bus to the FPGA 1130 machine. The board operates at 3.3V to interface with the FPGA board, but has level shifting chips to allow 5V logic levels for inputs. It is used with the debouncer board below. The buttons, toggle switches and rotary switches of the 1130 console, except for the 16 toggle switches that are mounted on the console printer faceplate, are routed through this concentrator and into the hardware on the FPGA board. Uses an MCP23017 to multiplex signals and several 74HC4050 level shifter buffers which tolerate 5V inputs and produce legal 3.3V outputs.

Input debouncer board

This debouncer will remove any bouncing of the state of the buttons as they are operated, where contacts produce a short term blizzard of on and off conditions as the physical switch is pressed or released, but the intent is to record just the selected final condition - 1 or 0 - which the switch will settle down to deliver steadily a few milliseconds after it is operated. The debouncer eliminates those glitchy short term effects and passes through only the intended change, on to off or off to on. This board as built implements debouncers for 24 switches/buttons, more chips are added as more buttons are required. Uses MC14490 debouncer chips which operate on 5V, producing the signals that are shifted down to 3.3V signals by the buffers on the concentrator board above.

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.