March 27th, 2002
This is the first of 2 large terminal wiring boards. Each board can handle 128 individual switch inputs. The board itself is 1/2" MDF (Medium Density Fiberboard). The picture here show the terminal blocks for the "data bit" connections. The terminals are labeled "DB0" through "DB7" from top to bottom. They'll be wired into the 8 position terminal block on the EPIC switch matrix board. This is the next stage in the process. The dual row terminal block is where the matrix diode will be mounted to. The diodes are very important - they are what allows the EPIC matrix scanner to "see" all the switch positions, even if many (or all!) or in the closed position. The last terminal block, the "row" block has been installed. Each one of these are a single row, 8 position terminal block. All 8 positions have been wired together to create a "bus". Each one of these will connect to one of the 32 positions on the EPIC switch matrix board. Each one of these is described as a "Row". Each EPIC switch "module" has 16 rows and thus will support 128 switches. Here is the completed terminal board. As you can see, there are 16 sets of 3 terminal blocks. Each set of 3 is a Module Row. In this case, Module 1, Row 0 begins at the upper left corner of the board. Row numbers increase going right. Module 1, Row 8 begins at the lower left corner of the board. This is what the terminal board looks like in it's "installed" position. The board slides out for easy maintenance, which is VERY important when dealing with complex wiring bundles. Eventually the boards will glide on ball bearing drawer slides, but for this stage of construction, a simple shelf fit works fine. This space will hold both of the large terminal boards. A third, much smaller terminal board will be also located in here (somewhere). The smaller board will break out the 48 inputs that are present in the scan matrix that's accessable from the 15 pin joystick connectors on the first expansion module. Here is a close-up of how the diodes are installed. The switch wires will go from the open leg of the dual row terminal block and to the bus-wired 8 position terminal block. There will be additional wiring to link the diodes as shown in this schematic.