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DIGITAL PDP8/I Continued
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I actually use my own real VT220 to communicate with my PiDP-8 emulator

As mentioned in a previous post, this family of devices was used in many of the in-house test systems for the central incoming test group also located in our building as well as some of the newer PDP-11 series devices.

It has a very small instruction set and a word size of 12 bits. First devices where delivered with 4K words that could be extended to 32K words using an extension board in the integrated circuit models.

These devices supported ASR33 ‘typewriters’ that also supported paper tape for entering and saving code. There were also TU56 tape (184K) drives which essentially worked more like random access disk drives than what we traditionally think of as tape drives. There was also disturbingly large disk drives with seriously small storage space (less than 3Mb). Later in the series, there was also an 8″ floppy called the RX01, which I personally encountered on the WT78 Word Processor while doing my college homework (with permission… after hours at the office). A slightly larger storage capacity 8″ RX02 arrived the same year.

Configuring a PDP-8 in SIMH

The environment I’m using is based on Oscar Vermeulen’s Pidp8 (a Raspberry Pi Zero with with switches and led’s emulating a PDP-8 front panel). Oscar assembled a custom release of SIMH 4.0 including a GPIO handler to drive the LEDS and read the front panel switches for a full retro-experience.

There is a website that stores many PDP-8 device images that can be used with the SIMH/PDP8 emulator. They are found here, pdp8 online

Examples:

$wget http://www.pdp8online.com/ftp/images/misc_floppy/os8_v3d_bin_1.rx01
$wget http://www.pdp8online.com/ftp/images/misc_floppy/os8_v3d_bin_2.rx01


Using the PiDP-8/I front panel

If it’s not clear, when the top of the switches on the panel are pressed IN, the switch is in a “0” state, and when the bottom of the switch is pressed in it represents a “1” state.

Node.js with Mongodb build

Post install cleanup


sudo apt-get update
sudo apt-get remove --purge wolfram-engine
sudo apt-get remove --purge minecraft-pi python-minecraftpi
sudo apt-get remove --purge penguinspuzzle
sudo apt-get remove --purge scratch nuscratch sonic-pi


Remote Access with VNC

sudo apt-get install tightvncserver

Setup password…

vncserver -geometry 1024x728 -depth 24 -dpi 120

Kill the server in preparation for boot automation…

vncserver -kill :1

Setup the autostart init.d based file in `/etc/init.d`

sudo nano /etc/init.d/vncserver

File contents:

#!/bin/sh
### BEGIN INIT INFO
# Provides: VNC
# Required-Start: $local_fs
# Required-Stop:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start or stop the VNC server
### END INIT INFO

PATH=/sbin:/usr/sbin:/bin:/usr/bin

eval cd ~pi

case “$1” in
start)
su pi -c “/usr/bin/vncserver :1 -geometry 1024×728 -depth 24”
echo “Started VNC server.”
;;
stop)
su pi -c “/usr/bin/vncserver -kill :1”
echo “Stopped VNC server.”
;;
*)
echo “Usage: vncserver [start|stop]” >&2
exit 3
;;
esac

exit 0

The following commands will set up the new file so it will operate correctly…

sudo chown root:root /etc/init.d/vncserver
sudo chmod 755 /etc/init.d/vncserver
sudo update-rc.d vncserver defaults

Now we need to add cut/paste support…

sudo apt-get install autocutsel


and add it to the VNC startup file in the PI user account…

sudo nano .vnc/xstartup

so it looks like this:


#!/bin/sh
autocutsel -s CLIPBOARD -fork
autocutsel -s PRIMARY -fork
xrdb $HOME/.Xresources
xsetroot -solid grey

#x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#x-window-manager &
# Fix to make GNOME work
export XKL_XMODMAP_DISABLE=1
/etc/X11/Xsession

Installing Nodejs dependencies:

build-essential and git

sudo apt-get install build-essential git

Node.js

wget http://node-arm.herokuapp.com/node_latest_armhf.deb sudo dpkg -i node_latest_armhf.deb

MongoDB

git clone https://github.com/svvitale/mongo4pi.git cd mongo4pi sudo ./install.sh