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The basic elements of printed code are bars and half-bars representing binary “l”’s and “0”’s respectively. These bars are printed in one of two for matting ?elds, namely, A-?eld or B-?eld. A-?eld identi ?es 5 digit ZIP code containing 32 bars and 9 digit ZIP code with 52 bars. B-?eld expands the 5 digit At-?eld to include 37 additional bars to comprise a 9-digit ZIP code. With further reference to FIG. 3, the operator selects the Mode Select 32 switch to run “Operator Paced” mode. The Main Processor and Memory 42 which is constantly looking at the Mode Select 32 inputs, through the I/O Data Bus Controller 41 now knows which program to run in memory. Also the Mode Se» lect 32 switch sets the Data Path Controller 44 to obtain Keyboard I/O Interface 43 data and sends it to EZR 28d by way of twenty signal lines. The Main Processor and Memory 42 now waits for signals from the Key board 20 as the operator keys in the ZIP code informa tion. These signals pass through the Data Path Control ler 44, Keyboard I/O Interface 43 and are latched into the I/O Data Bus Controller 41, where they are read by the Main Processor 42. The Main Processor and Mem ory 42 assembles the information and determines the equivalent POSTNET bar code. A “clutch” signal is provided to console 12 via line 11 to start the print cycle. The mail piece 16 in FIG. 1, travelling in the transport path, is sensed by the Mail Piece Detector 44 (FIG. 4) found in Print Controller/Synchronizer 40. The POSTNET bar code is printed on the mail piece as it moves past the Print Head 50 disposed in Code 5 Printer 10. Further downstream, a Bar Code Print De tector 61 situated in Print Controller/Synchronizer 40, checks the print quality to see if proper printing took place. The Main Processor and Memory 42 also trans mits the keyed information to the EZR 28d through the data path comprising I/O Data Bus Controller 41, Key board I/O Interface 43 and Data Path Controller 44. This information enables EZR to sort the mail piece to the proper bin. If the Console Code Printer 10 is not being used and the Mode Select 32 is set to “Manual" (no print), the Data Path Controller 44 allows the key board signals to be transmitted directly to EZR I/O Station 28d as in the present manner. With reference to FIG. 4, the following provides more detailed information on the Data Path Controller 44, Keyboard I/O Interface 43, U0 Data Bus Control ler 41, Main Processor and Memory 42 and Print Con troller/Synchronizer 40. The Data Path Controller 44 is used to interconnect the Console Code Printer interface 30 with Keyboard 20 and EZR 28. Reed relays 68 are provided to physi cally switch between EZR 28 and Keyboard 20 or EZR 28 and Console Code Printer Interface 30. The Key board I/O Interface 43 includes all of the interconnec tions required to convert keystrokes from Data Path Controller 44 to binary coded decimal (BCD) unit 66 and to provide debounce to ?lter out noise from the keyboard and N-key rollover protection for simulta neous keying in unit 77. It also converts BCD to Deci mal in unit 67 and interfaces to the I/O Data Bus Con troller 41 5-bit bidirectional port. The U0 Data Bus Controller 41 is a programmable interface designed for use with microcomputer systems. Its function is that of a general purpose I/O unit to interface peripheral equipment to the microprocessor system bus. The U0 Data Bus Controller 41 performs three operations: Basic I/O, Strobed Output and Bidi rectional Bus. Basic I/O provides simple input and out put operations, for example, 3-bit inputs from Mode Select 32 or 2-bit outputs to Counter 59. Strobed Output is a “handshaking” device used to interface with the Shift Register 52. Four signals namely, OBF, ACK, INT and Clo_ck Pulse (1)1 and AND gates 75 and 76 are utilized. When signals INT and OBF go low, INT al lows data to be loaded into the Shift Register 52 upon the next clock pulse ¢1; also ¢1 allows the ACK signal to go low and informs the I/O Data Bus Controller 41 that data has to be accepted. The OBF goes high due to the ACK going low. ACK goes high on the next clock pulse (b1 and in turn pulls INT high. Clock pulse ¢1 then allows data to be shifted out of the Shift Register 52. The third operation, Bidirectional Bus, allows both transmitting and receiving data on a single line such as the interface to Keyboard I/O Interface 43 or 8-bit Data Bus to Main Processor and Memory 42. The Main Processor and Memory 42 are comprised of three basic blocks, CPU 70, PROM 73 and RAM 72. Communication between blocks and I/O Data Bus Controller 41 is accomplished by an 8-bit Data Bus, 8-bit Address Bus and R/W pulse. The CPU 70, via programs stored in PROM 73, controls synchronization of data from keyboard 20 via Interrupt Signal INTI to the CPU 70 and sends more POSTNET data to Shift Register 52 via Interrupt Signal, INT2. Upon actuation of the advance key from keyboard 20, the “clutch” signal line 11 is sent by the CPU 70 to console 12, syn chronizing output data to EZR 28.