The A154BB has provisions for jumper selectable addressing for both inverting and non-inverting logic. Up to 15 buffer boards can be addressed. The A154BB "UP" translates from a low voltage to a high voltage normally (i.e. TTL to CMOS): but can "DOWN" translate from a high to a low voltage (i.e. CMOS to TTL). The input thresholds of a buss system can be shifted to TTL compatibility and no sequencing is required on power systems or inputs. The A154BB operates at voltages from 3.0v to 15v and is capable of driving 16 low power TTL loads, 15 HTL loads or 9 low power SHOTTKY TTL loads. The input currect requirements are low (1 microamp or less).
When used with the A169LD/1-2 Digitizer in the BCD mode, the A154BB provides the following signals:
DATA VALUE SIGNALS:
The A154BB can of course be used with other devices for other types of data and has 25 inputs and 25 outputs available for the purpose.
CONTROL SIGNALS: The A154BB has provisions for 5 remote signals that can be used for control. One of these can be jumper selectable as addressable or active at all times (i.e.41).
ADDRESS LINES: The BB has provisions for four-bit address lines, jumper selectable for options "A" or "B". Option "A" for inverted logic Low true and Option "B" for non-inverted logic High tru
NOTE: TERMINALS 26 THRU 30 ARE NOT USED. 35AND 36 ARE SPARES. 42 IS FUTURE, 43 IS +VCC, 44 IS +VDD, AND 45 IS GND.
The A169LD/1-2 signals fall into three main groups: Data values, Status Signals, and Control Signals. The four-bit Address Lines (i.e. 1,2,4,8) are for optional use.
DATA VALUES are binary related components (B1,B2,B4,B8) of each digit (D1-LSD, D2, D3, D4, D5-MSD) in the 5 digit value. In addition, there is one line dedicated to the polarity (i.e. NEGATIVE).
STATUS SIGNALS are mode indicators of the front panel functions and information LB/KG, GROSS/NET/ OVERLOAD (-FFFF1-2). In addition, VALID is a status signal of "DATA VALID" that is active (Low Option B) then the tri-state output ports have been updated with the results of a just completed conversion in the A169LD/1-2. It is a pulsed gating signal.
CONTROL SIGNALS are active Low for input to the A169LD/1-2 and remain inactive unless used. HOLD inhibits change in output data and holds the last reading until released (i.e. HOLD Option B). LB/KG is not installed, this is for future software modifications. TARE is a toggle function as is NET/GROSS and CHECK (i.e. NET/GROSS, TARE, CHECK Option B). Some signals are not used it the A154BB such as output disable which puts the status signals and data values into tri-state mode when driven high. This forces the buss to a high impedance state, but sequential operation of conversion is not inhibited. This function and some status signals such as CENTER OF ZERO are only available through interfacing directly with the A169 or A166TB.
The A169LD/1-2 is 4-bit addressable from a connector on the rear and is not addressed when used with the A154BB (i.e. address pos. 0).
Remember Option "A" is the inverse of Option "B" and except on special order the data values are the inverse of the controls signals. Also, remember the A169LD/1-2 has an output that is switch selectable as High True or Low True and that it can be binary or BCD. For a one to one positive logic interface use Option "B", and for an inverse negative logic interface use Option "A".
NOTE: THE DATA VALUES AND STATUS SIGNALS CAN BE SWITCH SELECTED ON THE A169LD/1-2 AS HIGH TRUE OR LOW TRUE, BUT THE CONTROL SIGNALS ARE PULLED HIGH AND ARE ACTIVE LOW INPUTS (i.e. HOLD, LB/KG, TARE, NET/GROSS, AND CHECK). THESE SIGNALS ARE INPUTS TO THE A169LD/1-2 AND MUST BE CONSIDERED CAREFULLY.
A154BB BUFFER BOARD
*OPTION "A" IS USED IN INVERTED LOGIC BUSS
The A154BB is a circuit board that contains a 50 pin (2 rows of 25 pins each) connector for ribbon cable, 45 terminal blocks, and a 50 pin edge connector (2 sides of 25 pins each). The board measures 6" x 10" x 1-1/2" high and can be mounted in any position to a back pan. The terminal blocks are barrier type strips for up to four 18 AWG or two 14 AWG wires each. The 50 pin edge connector is the interface I/O and the 50 pin ribbon connector output is in parallel with the corresponding terminal block.