Responsi Kuliah Sistem Digital R1 dan R2

Hasil evaluasi tugas rumah (home work) #2 dan kuis #1 menunjukkan:

  1. ada yang belum mengerti simbol gerbang logika dan operasi fungsinya (AND,OR, NOT, NOR dan NAND);
  2. banyak yang belum mengerti implementasi rangkaian logika dari ekspresi fungsi logika;
  3. banyak yang belum mengerti konversi dari gerbang AND-OR ke NAND-NAND dan OR-AND ke NOR-NOR;
  4. ada yang belum mengerti konsep dasar sistem digital;

Kuantitasnya tidak saya sebutkan, hanya kualitatif ada dan banyak. Banyak sebab mengapa bisa begitu. Bisa dari saya  atau dari mahasiswa sendiri.

Saya ingin membuka wacana diadakannya responsi untuk kuliah ini. Responsi selama 1 jam di luar kuliah regular. Responsi ini hanya membahas soal dan solusi dari suatu rancangan sistem digital. Saya beranggapan mungkin ini tahun pertama mahasiswa belajar tentang sistem komputer/digital, dan kebetulan materinya juga fundamental dan “baru”, sehingga perlu latihan lebih banyak.

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Assumptions Used in Digital Abstraction

In order to analyze and design digital circuits, a number of assumptions are made that underlie digital abstraction. It’s assumed that a circuit behaves in a ideal manner, allowing a designer to think in terms of 1s and 0s, without being concerned about the circuit’s electrical behavior and physical implementation.

There are five assumptions occasionally being made:

  1. All signals take on appropriate low and high voltages (their logic levels) representing discrete values 0 and 1. It imposes the physical circuit must not violate voltage level specifications in terms of component’s voltage threshold: VoH, VoL, ViH, ViL and noise margin;
  2. The current loads on circuit components are reasonable. An idealized component should be able to source or sink as much current at the output as its load requires without affecting the logic levels. It imposes the physical circuit must meet the static loading constraints in terms of component’s static load currents: IoH, IoL, IiH and IiL;
  3. All signals change between logic levels instantaneously. Due to component’s capacitive loading, the physical circuit must meet the propagation delay constraints when logic changes in terms of tpd;
  4. Wires are perfect conductors that propagate signals with no delay which means a change in the value of a signal at the output of a component is seen instantaneously at the input of other connected components. It imposes the circuit must guarantee its signal integrity due to parasitic load in wires;
  5. In a sequential circuit, a flip-flop stores the value of its data input at the moment the clock input changes (either edge-triggered or level-triggered) and the stored value is reflected on the output instantaneously. It imposes the circuit must meet timing constraint.

Activating Revision Control in Lyx

Lyx supports document revision control for collaborative document editing. It uses rcs, a gnu revision control system, for that purpose. You and your colleges then can register, checkout, merge and commit into your shared documents.

In Ubuntu Lucid, It was not installed by default when you installed Lyx package. So, you have to install rcs package using apt to enable Lyx revision control.

$> sudo aptitude install rcs

That’s it. You now can use revision control feature for your document. It is found at Lyx File menu.

First, register your document and than checkout it for editing.