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A project log for DL1416SmarTerm LED Computer/Terminal

Old and new come together for an old school intelligent terminal.

Dan JulioDan Julio 10/29/2018 at 00:180 Comments

Ever since including a printer with this project, I've been interested in somehow having the system able to print out old-school banners on the printer.  My BSD-derived Mac still has the program (type "banner" in a terminal).  Over the last couple of years I have been showing the computer at various shows and exhibits and have created a demo version of the firmware that does stuff like reset itself to a known state and display inviting information after a period of inactivity.  Recently I also introduced the idea of "virtual host" programs into the firmware.  The feature is intended to make it possible to have programs run locally and interface to the built-in terminal emulator as though it was connected to some external system (without having to have an external system).  I moved the Eliza module over to the new system and then went out search for the source to banner which I found in an online repository of an ancient version of BSD unix (which I can't seem to find again as I write this).

Porting it was fairly straightforward.  As discussed in the wiki article about the program, the original program (included in the downloads section) is a pretty big hack with two hand-crafted tables of font and index information.  It expects to run as a command line program outputting directly to stdout.  I had to change it into cooperative multitasking process interfacing with the printer buffer in the main firmware (and relearning - yet again - about buffer management and flow-control...).  I ended up having it load all the lines for one character at a time and waiting for a token passed through all the buffers to be returned by the printer (via my serial_to_parallel sketch that interfaces the parallel-port printer to the computer's serial output).

The virtual hosts are now selected via the terminal's configuration menu.  Code for anyone who is interested is in github (dl1416SmartTerm_demo).