Saturday, November 16, 2013

Apple IIc as a dumb text terminal.

Using you old computer hardware with modern equipment.

If you happen to have Apple II (IIc) computer and you think it is just taking space, do not put it in the trash, sell or donate just yet. The thing is, you own it because perhaps you purchased it long time ago, or got it as a gift and at some time liked it. It gave you hours of fun and helped to introduce you into the computing world. Whatever the reason, it may make your heart heavy to let it go. Well, you can still use it! Consider this - Apple IIc has a good serial port hardware driver and can be easily interfaced with modern equipment that is also equipped with a serial or USB ports (with USB to serial converter). All that is needed on the Apple side is a terminal emulation software and a serial null-modem cable adaptor that converts the Apple's mini-din to the DB-9 connector seen on modern PC computers. All the information I needed in order to turn my Apple IIc into the serial dumb terminal I found here:


and here:


First I prepared 3 blank floppy disks for Modem MGR software. I used AppleWorks software which I happen to have purchased with my Apple IIc. To transfer the Modem MGR images to Apple, you need ADT Pro client on the Apple side and a server on the PC side. Both are available on the internet as well as detailed instructions how to install and configure them, so I will not duplicate it here. Just check out the web site:


After the transfer of Modem MGR software, I had 3 disks: Installation, Utilities and Work. First I inserted and booted the Installation disk on my Apple and follow the instructions. I configured the software to work in 80-column mode (menu option 2) video driver, non-smart modem (menu option 10) and saved the configuration back to the work disk.
Next I connected the Apple's serial port to my DSL (Damn Small Linux) server. The server runs a script:

#!/bin/bash

while true
do
/sbin/getty -L 9600 ttyS1 vt100
done

The connection via standard serial cable and the mini-din to DB-9 adapter requires no null-modem connector, since the mini-din to DB-9 adapter cable is already a NULL modem. However I used the null modem serial cable and wondered for some time why this did not work. Then I had to add extra null-modem adapter.

Once computers were connected, I booted Modem MGR work disk on the Apple. It displays a bunch of options that can be accessed by pressing ESC key followed by the letter. At any time, I can press ESC and Shift-? to re-display the list of available options.

The first step is to setup the modem baud rate, which in my case is 9600. Next, the data format - number of bits, the parity and the number of stop bits: 8-N-1. The last step is to enter the Modem MGR into the terminal emulation mode, which is achieved by pressing ESC and ':' (colon) and then pressing V for loading the VT220 terminal emulation mode. Then I pressed enter and voila! - the login prompt appeared. Even though on the server side 'getty' runs in vt100 mode, I experienced no issues. This of course is easily adjusted on the server side.


Pictures:

Image 1: Transferring Modem MGR images to Apple 2c diskettes - client side.

Image 2: Transferring disk images - server side.


Image 3: A working text terminal emulator on Apple IIc.

Image 4: The output from 'top' command - it ran well and there were no emulation issues.
It was a fun little project. Now whenever I want to  have retro computing experience I can connect to my DSL server with Apple IIc and run Z-machine emulator to play one of the Infocom's text adventures.

Thank you for reading.

Marek Karcz, 11/16/2013