Resistor–transistor logic

<p>Resistor–transistor logic (RTL), sometimes also known as transistor–resistor logic (TRL), is a class of <a href="/facts/Digital_circuit/vWgfC29C">digital circuits</a> built using <a href="/facts/Resistor/JrsGReM6">resistors</a> as the input network and <a href="/facts/Bipolar_junction_transistor/9BMcGv5Q">bipolar junction transistors</a> (BJTs) as switching devices. RTL is the earliest class of transistorized digital logic circuit; it was succeeded by <a href="/facts/Diode%25E2%2580%2593transistor_logic/DmLg6WBK">diode–transistor logic</a> (DTL) and <a href="/facts/Transistor%25E2%2580%2593transistor_logic/z4bvHotl">transistor–transistor logic</a> (TTL). 
</p><p>RTL circuits were first constructed with <a href="/facts/Discrete_component/F3NBVv4Q">discrete components</a>, but in 1961 it became the first digital <a href="/facts/Logic_family/QlEgIecX">logic family</a> to be produced as a <a href="/facts/Monolithic_integrated_circuit/fjn6vg7C">monolithic integrated circuit</a>. RTL integrated circuits were used in the <a href="/facts/Apollo_Guidance_Computer/xGxHlrXY">Apollo Guidance Computer</a>, whose design began in 1961 and which first flew in 1966.
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Resistor–transistor logic open-in-new

Resistor–transistor logic