The Apollo Slave display converts numerical BCD data supplied by equipment such as programmable controllers, into seven segment LED display information. The Slave display is available in 3, 4, 5 and 6-digit versions, in either a 5 VDC or 10 to 28 VDC (3 and 5-digit versions have a "-" sign). The unit has three DIP switch selectable decimal points for displaying in 10ths, 100ths and 1000ths. Other DIP switches allow selection of 0 or 1 true logic and pull-down or pull-up resistors for both the data and strobe inputs. The unit can display the numbers 0-9 by sending the corresponding BCD information. Individual digits can be blanked by sending a Binary code greater than 9. For the 3 and 5-digit versions, the minus sign is activated by applying the selected logic true level to the terminal marked "(-) sign" then strobing the terminal marked "(-) STR". Four optional accessory boards provide terminal blocks for easy wire hookup and DIP sockets to cascade the BCD lines to other units. Models ATB1 (3 and 4-digit) and ATB3 (5 and 6-digit) contain all terminal block positions and are used when hooking up one Slave display or as the first in a series of cascaded displays. Models ATB2 (3 and 4-digit) and ATB4 (5 and 6-digit) do not have the terminal blocks for the 16 and 24 BCD data inputs. These boards are available for use in cascaded systems where the ACA1 DIP plug cable assembly is used to connect the data inputs.