Uploaded 11_3_2019

Wheelwriter/Documents/Datasheet.txt

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+
+MicroCore Labs - IBM Wheelwriter Printer Option
+-------------------------------------------------
+
+
+Description:
+------------
+ This is an FPGA project which allows RS232 access to an IBM Wheelwriter Typewriter. 
+ 
+ Using a terminal running at 9600 baud  (9600,n,8,1), the user can directly send characters to the typewriter. 
+ They can also cut and paste long documents into the terminal, which will be printed by the typewriter.
+ The FPGA uses XON/XOFF for flow control as well as a 1,000 character deep FIFO so that no characters are lost.
+ 
+ It has been tested on an IBM Wheelwriter 5, however other IBM typewriters such as the Wheelwriter 3 and 6 may also work.
+ The only connection needed to the typewriter is via two pins within the access panel at the top rear of the typewriter.
+ 
+ While any FPGA can be used, this project uses the Lattice XO2 Breakout Board which contains a USB interface that provides 
+ power and a RS232 serial port.  To use the USB serial port, the user will need to populate the two resistors R14 and R15 
+ which connect the RS232 TX and RX lines between the FPGA and the FTDI USB IC.
+ 
+ Alternatively, a second set of RS232 TX and RX pins are available which can be connected to any 3.3V compatible serial port.
+ This was provided to allow to user to connect any type of serial port, including vintage computers. Just make sure the TTL signalling
+ out of the converter is 3.3V to the FPGA.  Both serial connections can be connected at the same time, however only one can be used at a time.
+ In both cases, the baud rate is fixed to 9600 baud only.
+ 
+ 
+Architecture:
+-------------
+1) RS232 RX controller - fixed to 9600 baud
+2) RX character FIFO - 1,000 characters deep - flags used to signal RS232 transmit of XON/XOFF
+3) RS232 TX controller - fixed to 9600 baud - Used to send XON/XOFF flow control characters
+4) Main Controller - Pulls new characters from the RX_FIFO and sends the appropriate command sequence to the IBM TX_FIFO
+5) IBM Bus Controller - Pulls commands from the FIFO and sends them serially over the IBM_BUS
+6) Bus Snooper - Used to convert IBM serial data into parallel data to be observed on a logic analyzer. Not used for the design, just for debug
+
+
+Notes:
+-------
+- The IBM_BUS uses 5 volt logic, so a 5V to 3.3V bidirectional level shifter must be used. I used a Xilinx EPLD board, 
+  but any technology will work that provideds this functionality.
+- Both serial ports on the FPGA have light internal pullups to keep them from changing when not connected.
+
+
+Pinout
+-------
+- The pinout for the FPGA is described in the mclwr1.lpf file
+- The IBM Wheelwriter pins of interest are: 4=GND and 5=IBM_BUS.   Pin#1 is on the left when looking at the typewriter from the front.
+
+
+
+ 
+