User:Legalize/Video Outlines

Existing Gaps

Identified gaps in existing video content:

• There isn't any discussion of how technology and terminology of serial communications evolved from manual telegraphs to telegraph machinery to teletype machinery to serial communication between digital devices.
• While there are some teardown videos of terminals, there isn't any discussion of the architecture of a terminal and how it parallels the architecture of a microcomputer. A number of terminals are designed around a main bus motherboard with options and elements of the terminal as cards plugged into the motherboard (Tek 401x, HP 264x, VT1xx to a certain extent, etc.)
• Terminals can exhibit some interesting digital circuit design ideas. The B100 is basically a giant microcoded state machine design built out of discrete logic and a PROM for the microcode. This is a general design technique that is still applicable today, even if you would plop it all inside an FPGA instead of discrete logic chips. There is also a Basic Four terminal that is implemented with discrete logic, but I can't recall if it is done as a microcoded state machine as well.
• There isn't anything out there demonstrating the composite video overlay/underlay hacks with the VT100 advanced video option.
• There isn't anything out there showcasing the evolution/variation in keyboards among terminals before everything became defacto IBM 101 key keyboards. (Although there are keyboard keyswitch fetishist videos out there, it's really switch porn, they don't explain anything about what makes the switches different.)
• While there are lots of teletype porn videos out there, again hardly any of them explain how anything works. Watching something operate is more interesting if someone is explaining to you what you are seeing and how it works together. Otherwise it's just 2 minutes of "wow, that is a loud machine that types".
• There is nothing explaining interactive vs. block mode terminals and how they define forms with fields, etc. (A little bit of this appears in the defcon style hack tn3270 videos, though.)
• The only videos that explain the basics of serial communication (start, data, parity, stop bits, framing, signal levels, etc) seem to be done by these indian/asian guys teaching electronics courses on youtube. They have horrible presentation style and a thick accent. (If their presentation style was OK/good, I wouldn't mind the accent.) The end result is as if you are attending a shitty rural community college getting substandard education.
• There is nothing that explains control codes and dumb terminals vs. smart terminals. Mixed in with that you'd want to add a discussion of padding needed to give terminals time to process and how it relates to TERMCAP etc.

Video Outlines

Serial Communication

1. Telegraph communication
2. Telegraph equipment
3. Mark/Space
4. Teletype equipment
5. Current loop
6. Baudot code
7. Serial communications links between computers
   1. Synchronous
      1. SDLC
      2. HDLC
      3. X.25
   2. Asynchronous
      1. RS-232
      2. RS-422
      3. RS-423
      4. RS-449
      5. RS-485
8. Modems
9. Serial ports
10. Framing
    1. Characters
       1. Start bits
       2. Data bits
       3. Parity bits
       4. Stop bits
    2. Packets
       1. Ethernet
       2. X.25
11. Interactive mode
12. Block mode

Architecture of a Video Terminal

1. CPU
   1. Discrete logic control circuit
   2. Microprocessor
2. Keyboard
   1. Printing keys
      1. ASCII printing characters
      2. Extended national language characters
   2. Control keys
   3. Function keys
   4. Numeric keypad
   5. Editing keys
   6. Evolution of modifiers (alt, shift, control, meta)
3. Communication ports
4. Video scanout
5. Video display
6. Peripherals
   1. Integral printer
   2. Local storage
   3. Joystick
   4. Dials