improve signals and add components interconnection information

Author: Daniel Rosner

slides/lectures/acs_cc/04/slides.md

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-src: ../../resources/signals/slides.md
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slides/lectures/fils_en/04/slides.md

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+src: ../../resources/signals/basic.md
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slides/lectures/resources/signals/ICs_same_voltage.svg

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+---
+layout: section
+---
+# Signals
+Digital Signals - Recap 
+
+---
+
+# Signals
+Analog vs Digital
+
+<div grid="~ cols-2">
+
+<div>
+
+- *analog signals* are *real* signals
+- *digital signals* are *a numerical representation* of an analog signal (software level)
+- hardware usually works with two-level digital signals (hardware level)
+
+#### Exceptions
+- in wireless and in high-speed cable communication things get more complicated
+
+> for PCB level / between integrated circuits on the same board / inside the same chip - things are a "a little simpler" - as detailed in the following
+
+</div>
+
+![AD](./a_d.png)
+
+</div>
+
+---
+
+# Why use digital in computing?
+
+<div grid="~ cols-2">
+
+<div>
+
+Signal that we *want* to generate with an output pin
+
+![Digital Step](./digital_step.svg)
+
+</div>
+
+<div>
+<v-click>
+
+Signal that what we actually generate
+
+![Analog Step](./analog_step.svg)
+</v-click>
+</div>
+
+</div>
+
+> Why we sill use it? Because after passing through an IC or a gate inside an IC - the signal si "rebuilt" and if the "digital discipline" described in the following is respected - we can preserve the information after numerous "passes". Thus, each element can behave with a large margin for error, yet the final result is correct.
+
+---
+---
+# Noise Margin
+
+<div align="center">
+
+![Noise](./noise.svg)
+
+</div>
+
+

slides/lectures/resources/signals/VCC1_smaller_VCC2.svg

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+---
+layout: section
+---
+# Digital Signals - recap & key points
+
+Recap from ED & key concepts usefull for PM
+
+
+
+---
+
+# Digital Signals - recap & key points
+
+#