Terminal Emulation

I run RSTS/E V7.0-07 on an emulated PDP 11/70. This is kind of cool, but would be useless without someway to access it. Best option would be an actual terminal, but for me they are too hard or too expensive to come by.

That leaves me with some sort of terminal emulation. Terminals on the 11/70 that I used in school tended to fall into two groups, paper and video. The video terminal screens of that time were close to being square and used a monospaced font (all the letters were the same size). The ones that I used VT52 and similar used a display of 80 columns and 24 lines. More modern computers use a more rectangular screen with fonts that are not monospaced and can (and do) change size.

For terminal emulation I have a choice of Windows (7, 8.1 and 10), android, Macintosh (6.0.8) and Apple II. I’ve tried several terminal emulator programs under Windows and they all have what I consider a drawback. An 80×24 screen is slightly bigger than a 4×6 index card. I still use both Putty and Tera Term on occasion but if I want to do anything serious I would prefer another option.

I haven’t ruled out the Macintosh, but as of yet I haven’t found a terminal program I would use on a regular basis.

That brings me to the Apple II. My first Apple II was an Apple //c with a 9″ monochrome monitor. About 10 years ago I was looking at some Apple IIs on eBay and saw one where the seller had it hooked up to an LCD monitor with great results. I sent a note to the seller telling him I wasn’t interested in the Apple II so much as what monitor he was using. He was very understanding and told me it was a Dell 2001fp. I bought one of those and shared it with my PC. It takes Composite, VGA, DVI and S-Video inputs and you can change with a push of a button on the front. This is what I use on my Apple //c now. It is a 20″ monitor, which after a 9″ monitor is pretty nice and is also more square (4:3) than the current monitors.

My Apple //c is connected by a serial/null modem cable to the PC that runs my emulated PDP 11/70. I use ZLink as terminal emulation software on the Apple //c and works very well for my purposes.

I uploaded a video of using the Apple //c and Dell 2001fp Monitor as an emulated terminal to YouTube at : https://youtu.be/y0Aok67byXk

New A/B Switch

On March 18, Daniel DiPietro posted on Facebook about adding an A/B switch to his Apple //c.  That way he could leave both a mouse and a joystick connected all the time and just change the switch to use either one.    I have done such things many times in the distant past, but never thought of it for this case.  When I read about it, it made so much sense that I decided to do the same thing.

Tuesday morning I ordered an all female DB9 serial A/B switch and a DB9 Male to Male Serial Cable from two different sellers on eBay.  One said delivery by Saturday and the other by Monday, yet the both came early Friday, yesterday.  Great service from both.  One thing that surprised me was the size of the A/B switch.  In the past I used the Black Box switches and they were quite a bit larger.  This box was about the size of a 100 count package of 3×5 cards.

I plugged in the cable from the Apple //c to the A/B switch and then connected the mouse and the joystick to the A and B ports on the switch.

I tested the mouse with Dazzle Draw and the Joystick with Columns, a Tetris like game.  Both worked as planned, so I printed out labels with my label maker and put them on the switch box.

Oregon Trail

Oregon trail has been documented historically in other places, but it first came out in 1971 and you accessed it using a teletype.  It went away for a few years and came back under MECC in 1974 and you still accessed by terminal.  I was in school all during the 70’s on the east coast, so I never ran into it.  MECC had it rewritten for the Apple II and released in 1985.

I got my first Apple computer at the end of 1984, an Apple //c.  Over the years, I kept an interest in the Apple II world and still have my original Apple //c.  It doesn’t work and have replaced it with a slightly newer version but, still hope to get it repaired.

I never heard of Oregon Trail until maybe twenty years later.  I’ve since then played the Apple II version using AppleWin and realized that it is exactly the kind of game I would have spent hours playing in school.  Of course, had I played it in school, it would have been using a teletype or other terminal, since the Apple II didn’t come out until several years after I finished school.

I was recently reading a history of the game and found a basic listing of one of the earlier versions was published in the May-June 1978 issue of Creative Computing.  I tracked a copy of this issue to Archive.org and printed out the article.  My plan is to enter this game into an emulated PDP 11/70 running RSTS/E and BASIC-PLUS giving it the feel to a certain extent of the original.  You would have to log on using a terminal in order to play the game.

Terminal Emulation, Apple //c & Mac SE

In August, I decided to use my Apple //c and my Macintosh SE as terminals on my emulated PDP 11(Puff).  I wanted them to work as video terminals.

In the past, when accessing Puff, I would use a telnet program on one of my pc’s.  I went with a pretty vanilla kind of setup.  I configured all terminals as LA36, and all the telnet programs I used worked.

When setting up this latest generation of Puff, I configured it so it would use com1: and com2: as vt100 terminals.

Com1: is set up at 1200,8n1 and that is where my //c is connected using a null modem cable.  Com2:, meanwhile is setup at 9600, 8n1 and is connected with a null modem cable to my Macintosh SE.  Instead of using telnet software I use a communications program on both machines to connect to Puff.

This is very much like using a dialup connection, so the first program I tried on the //c was ZLink.  I got it to work by matching the 1200, 8n1 parameters.  Using the Open Apple T command to change emulation to VT100.  The only program I knew of that worked differently on a display terminal was VT50PY, so I ran that.  It worked as I remembered, displaying a running a systat.

For software on the Mac side, I ran Mac Terminal, again VT50PY runs well on it.

At the high school we had two VT52 terminals and later received two more display terminals that were, I believe, VT100 compatible.  I don’t remember much about them, except they were amber screened and made with a crisp metal edged case.

Inspired, partly by David Moisan’s 2012 Retrochallange project Hac-Man, I was thinking I would recreate an old game or two.  I wanted to work on a game that used the VT100 ‘s cursor control abilities.  In high school I worked on a game I called GALAXY which was loosely based on the star trek games of that time.  It was written to be played on a display terminal only, as it required the ability to use cursor control to keep a grid on the screen and update it during play.

I did some research and found several sites with VT100 codes, but was missing the key to how to use them.  Johnny Billquist and Dennis Boone from comp.os.rsts came back with the key answer to cursor control.  Printing an escape character with the high bit set chr$(27+128) followed by the open square bracket, the row, a semicolon, the column (fixed column from colon, 18-sep-16) and the letter H positions the cursor.

PRINT CHR$(155);”[“;NUM1$(ROW%);”;”;NUM1$(COL%);”H”;

The semicolon at the end is important as it keeps the cursor there.

I wrote a simple program to position the cursor at each corner of the screen and print something.  It didn’t work on either the //c or the Mac.

David Moisan said said in his blog (https://davidcmoisan.wordpress.com/2012/07/05/hac-man-retrochallenge/) he used tera term, an open source windows program, in VT100 emulation and it worked.  I ran my copy and used telnet to connect to Puff.  When I ran my test program, it worked as I wanted it to.

That being the case, maybe the programs I was running on the //c and Mac weren’t as VT100 compatible as needed.  I tried ZLink on the Mac SE and when I connected, ran my test program and it worked.  On the Apple //c, I found ProTerm worked with my test program.  VT50PY would not run properly under either ProTerm on the //c or ZLink on the Mac, which made sense since it was written for the VT50 series of terminals.

UPDATE:  After testing both ProTerm and ZLink on the Apple //c, I found neither handles the graphics characters well.  Zlink just displays regular characters and ProTerm does not do corners or intersections with line drawing. (02-SEP-16)


Emulating the PDP 11

Years ago, I stumbled across an article about emulating the PDP 11 computer.  After doing a little more research I found a package of programs called SimH, which allowed you to emulate a number of computers.  Amongst these was an emulator program for the PDP 11 system.

RSTS/E stands for Resource Sharing, Time Sharing, Extended and systems that ran it quite often had dial up connections.  Our high school had several.  The emulators I have found let you set up dial up connections using telnet.

I set up a simulation of the PDP 11/70 that I used in high school.  I could not find a version of RSTS/E that was close to V06 that I used in high school so I installed one of the later version of RSTS/E, 9.2, I believe, and patched it with the y2K patch to fix dates.  I ran that for years to play with occasionally.

I later found a version that was much closer, V7.0.07.  This I installed and patched with a Y2K patch.  Again I ran this version for years.

Since 2003 or 2004, I’ve been running these simulations, and one thing has been missing, the ability to print seamlessly, just like a real 11/70.

In this time, I have looked at another emulator, Ersatz 11, from time to time.  It is a commercial emulator for businesses who need to retain their software, but replace their hardware.  They allow hobbyist use for smaller configurations, and that works for me.

Last fall, I bought a Rosewill PCI communications card for my PC.  It has two serial ports and one parallel port.  I bought it to replace a usb serial adapter that I used to move files back and forth between my PC and either my Apple //c or my Macintosh SE.

Recently, I was reading through the documentation of Ersatz and realized, that printing was something it does.  I decided to try it out.  I started setting it up and added a little something extra.

I set it up to assign both serial ports as terminals.  My apple //c is set up as KB1: and my Mac SE as KB2: using terminal emulation software on both machines.  I also setup to assign lp0: to the windows printer using OSPRINT:.

Last Update: 15-Aug-17 Fixed spelling error and added a comma.

We Begin Again…

We begin again, or I do anyway.  I started this blog once before and lost it after a number of posts.  With no backup, it was just gone.

Here, I will write about my experiences with vintage computers.  Specifically, I have five vintage Apple Computers; a //e, a //c, two Mac Pluses and a Mac SE.  I’ve worked and used others, and will write about them as time goes by.

My first Apple computer was an Apple //c.  Following that, I was given an Apple //e and bought a Mac Plus and a Mac SE.

Last Update: 26-Aug-15