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electronic:ttl:start [2021/04/09 06:23] – tonyelectronic:ttl:start [2026/09/26 20:58] (current) – tony
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 Early microcomputers used CRT displays driven by TTL level control signals. There was monochrome TTL, monochrome Hercules TTL (different sync frequencies, with bit mapped graphics), and CGA/EGA compatible TTL. Early microcomputers used CRT displays driven by TTL level control signals. There was monochrome TTL, monochrome Hercules TTL (different sync frequencies, with bit mapped graphics), and CGA/EGA compatible TTL.
  
-======TTL from VGA port======+===== TTL from VGA Port =====
 Driving TTL from VGA from a RaspberryPi 3 (( [[https://www.reddit.com/r/retrobattlestations/comments/5jslch/raspberry_pi_running_ibm5151_monitor_via_hdmivga/]])): Driving TTL from VGA from a RaspberryPi 3 (( [[https://www.reddit.com/r/retrobattlestations/comments/5jslch/raspberry_pi_running_ibm5151_monitor_via_hdmivga/]])):
  
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 Wiring diagram: Wiring diagram:
  
-HD15 6 -> DE9 1 +|HD15|6|->|DE9|1| 
-HD15 2 -> DE9 7 +|HD15|2|->|DE9|7| 
-HD15 13 -> DE9 8 +|HD15|13|->|DE9|8| 
-HD15 14 -> DE9 9+|HD15|14|->|DE9|9|
  
 Video settings from /boot/config.txt: Video settings from /boot/config.txt:
  
-# hercules/ibm5155 crt +|# hercules/ibm5155 crt| 
-hdmi_ignore_edid=0xa5000080  +|hdmi_ignore_edid=0xa5000080| 
-hdmi_group=2 +|hdmi_group=2| 
-hdmi_mode=87 +|hdmi_mode=87| 
-hdmi_timings=720 1 16 130 16 350 0 16 16 16 0 0 0 50 0 16257000 0+|hdmi_timings=720 1 16 130 16 350 0 16 16 16 0 0 0 50 0 16257000 0|
 ---- ----
 Others say: Others say:
 http://old.pinouts.ru/Video/MDA_pinout.shtml combine RGB signals on the VGA connector together with, say, 330 ohm resistors. Connect H-sync on VGA to H-sync on MDA, same for V-sync, and connect the ground and the MDA intensity line to ground. http://old.pinouts.ru/Video/MDA_pinout.shtml combine RGB signals on the VGA connector together with, say, 330 ohm resistors. Connect H-sync on VGA to H-sync on MDA, same for V-sync, and connect the ground and the MDA intensity line to ground.
  
-VGA outputs are supposed to be .7v (probably higher on some implementations without a proper 75 ohm load though) and MDA is TTL logic level, where >2.4V is considered a high, <.8 is considered a low, and in between is undefined....+VGA outputs are supposed to be 0.7v (probably higher on some implementations without a proper 75 ohm load though) and MDA is TTL logic level, where >2.4V is considered a high, <.8 is considered a low, and in between is undefined....
  
 ===== Hardware description ===== ===== Hardware description =====
 +\\
  
 ====== References and Additional Resources ====== ====== References and Additional Resources ======

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electronic/ttl/start.1617949434.txt.gz · Last modified: 2021/04/09 06:23 by tony
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