This article was written specifically for connecting a Brother EP-22 typewriter printer or the SMITH-CORONA DEVILLE III typewriter printer with the Messenger Module to the Zebra FDD 3000 Disk Drives. However, the article should be of help to anyone in connecting a Serial printer to the TS 2068.
As the 2068 does not have a Serial Port, the first requirement is a Serial Interface that matches the type of serial printer that you have. The second requirement is an Interface Driver program.
There are two main types of serial printers. Those that require a serial interface or port specifically designed for that printer, such as the OKIMATE 20 with the Commadore Plug and Print Module or the TS 2040. In the case of the 2040, a serial port is built into the computer connector block and the driver program is in the ROM. The other main type of serialprinters are those that require a RS 232(C) serial interface or port for the computer.
The FDD 3000 disk drive package has two partial, nine pin, RS 232(C) interfaces that are referred to as the Serial Communication Ports (SCPs), CH_A & CH_B. The Timex Disk Operating System (TOS) has the serial interface Driver Programs built into it. The TOS DEMO VA.2 disk has a program to support the LPRINT and LLIST commands, designed for use with CH_A. There is also a Keyboard Echo program for use with CH_A.
There are three types of RS 232(C) serial printers, those that use hardware handshake, those that use software handshake, and those that can use either type of handshake. Where possible, it is best to use hardware handshake protocol due to differing time required to empty the printer buffer and to do a carriage return/ line feed. All three types of RS 232(C) printers require only three wires to connect the interface to the printer.
HARDWARE HANDSHAKE: Interface Printer Transmitted Data -------------Received Data Data Terminal Ready-----Data Terminal Ready Signal Ground-----------------Signal Ground SOFTWARE HANDSHAKE: Interface Printer Transmitted Data---------------Received Data Received Data---------------Transmitted Data Signal Ground-----------------Signal Ground
I have purposely left out the pin numbers as those who do not have the FDD, the EP-22, or the Messenger Module and typewriter must determine these from their RS232 interface manual and their printer manual.
The standard pin numbering for a nine pin male connector and a 25 pin male connector when viewed looking at the front of the pins is as follows:
******************************************* *************** * 1 2 3 4 5 * * 6 7 8 9 * ********* ******************************************* * 1 2 3 4 5 6 7 8 9 10 11 12 13 * * 14 15 16 17 18 19 20 21 22 23 24 25 * ***********************************
If you view the female connector from the back end ( where the wires connect) the numbering on them will be as shown.
The proper connections for the FDD 3000 interface A to either the Brother EP-22 or the Messenger Module serial input are:
Interface Printer or Module 9 pin female B25 pin Male Pin Name Pin Name 2 Tx------------------------------3 RD 5 DTR----------------------------20 DTR 7 SG------------------------------7 SG
The connectors are available at Radio Shack:
Female 9 pin #276-1538 $2.49
Hood 9 pin #276-1539 $1.99
Male 25 pin #276-1547 $1.99
Hood 25 pin #276-1549 $1.99
Any three wire cable up to 50 feet long can be used. You may wish to use a joystick extension cable available from Radio Shack, cutting off and discarding the male connector. The wire colors on the one I have are Pin 2-red, Pin 5-green, and Pin 7 is grey. To be safe you should check them.
Now that you have your cable made, plug the 9 pin connector into the A channel serial interface of the FDD 3000. As you look at the back of the unit, it is the one on the right and is labeled. Making certain that all power is off, plug the other end into the EP-22 printer or into the serial input of the Messenger Module.
Are you ready to use your printer? Not really as you must first configure the interface driver program for your printer. This is done in TOS using the FORMAT * command,so you should be sure that the disk is protected by the write protection tab. After powering up the computer and then the FDD 3000, insert the DEMO disk in the A drive. When the drive light goes off, type in the following command:
FORMAT *":CH_A"then press ENTER. You will be prompted to key the required answers for your printer. The EP-22 has only the choice of 75 or 300 Baud rate. The character bits are eight and one stop bit. No parity check. The Messenger Module has dip switches for optional settings. Using the configurations as set by the factory you would answer the questions as follows:
QUESTION EP-22 MODULE 1. Text or Bytes? T T 2. Auto line feed? N N 3. XON / XOFF? N N 4. Input with wait N N 5. Baud rate? G I 6. Parity? N E 7. Stop bits? A A 8. Bits/char? D D
After all the questions have been answered you are back in BASIC. Type in:
GO TO *":DEMO:UTIL"then press ENTER
There are three utility programs on the TOS DEMO disk that can be used by a serial typewriter printer. “TYPE” ( no extension ), a keyboard echo program. “LPRINT” ( no extension ), a BASIC loader for the machine code LPRINT and LLIST support program for the SCP CH_A, named “LPRINT.COD”CODE 23297.
Power up the typewriter. With the EP-22, use the CP mode, change from the typewriter to printer mode, and press the CONT button. You should now see in the printer display “ON LINE 300 BAUD”.
With the Messenger Module and the Smith-Corona typewriter, set the pitch desired, turn on the keyboard, hold down the CODE key and press the “P” key. The red program light should come on.
Type into the computer:
LOAD *"TYPE"Then press ENTER. When the program has loaded, the prompt “Do You Have a Printer (Y/N)? will appear on the screen. Answer with a Y and when the cursor appears press ENTER. You should now be able to use the computer keyboard and both the screen and printer will echo the key that is pressed. The ENTER key acts as a carriage return/ line feed. If the program hangs up, the typewriter was not on line, the connections are bad, or the cable is wired incorrectly.
If all goes well, break out of the program using the BREAK key. Type in:
CLOSE # *1Then press ENTER. Type in:
LOAD *"LPRINT"Then press ENTER. When the program has loaded, type in:
RUNThen press ENTER. You should now be able to use the normal LLIST or LPRINT commands.
You can now avoid reconfiguring the SCP CH_A by FORMATting new disks. The DEMO disk also has a utility program named “LOSYS” that will allow you to change the default setting on existing disks, after configuring a SCP, without losing the data on your disks.