fredag 16 september 2016

MAME: Esselte 100 and serial support

The Esselte 100 has a rudimentary serial port that is available on the multi faceted I/O port labeled "Printer" where also the different measurement experiments are attached. In order to use the serial port in the emulator it has to be started with an emulated null modem cable attached to something.

In this example we will run it against a Telnet terminal. In order to get out of the emulated world and into the real world we attach it to a bit banger device which in turn needs to be attached to a socket server. These parts will translate the emulation time serial communication into a data stream through the socket server to the telnet terminal.


The null modem has built in support for the bitbanger and does the translation between stream data and the selected baudrate. This is how you set up MAME to work this way:

First you can check what devices is supported by a certain driver. The driver for Esselte 100 is called e100 and the option to use is called -listdevices:


The interesting information here is "RS232 Port" because it is a slot device which we can explore further with the -listslots option:


Here we can see that the RS232 port device called 'rs232' supports null modem. From not so well known sources we also know that the null modem support a bitbanger device which in turn accepts a socket address as argument like this:


This will start MAME as we want it to, The connection between the PIA pins and the rs232 device is defined in the emulation driver for the Esselte 100 and not something we can change from the command line. Once MAME is started you can open Putty.exe or you favorite Telnet terminal and connect it to the socket server using 127.0.0.1 (or the IP address of the machine running MAME if you are using a Telnet terminal on another machine) and port 4321 ( can be change to any port ).

Skip through the alerts at the beginning af the MAME session and at his point you will see two windows, one with Esselte 100 and one with the Telnet terminal:


The Esselte 100 starts in 7 bit, 1 start bit, 2 stop bits and 300 baud so we need to set up the null modem to talk to us at this speed through the internal menu system of MAME. This is enabled by pressing Scroll Lock and then TAB. Enter the "Machine Configuration" menu and change the settings accordingly:

Press TAB to exit the menu and select the Esselte 100 window. In order to use the serial port easy there is a terminal mode built in which takes the baud rate as argument:


Press some keys and there should be text in your Telnet terminal, the emulation has escaped into the real world!! :)

Not much more works at this point but this is a generic method how to connect emulated system with each other or to the outside world, enjoy!

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