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Differentiate between minimum and maximum mode of opeartion of 8086 microprocessor.

Mumbai University > Electronics and Telecommunication > Sem 4 > Microprocessor and peripherals

Marks: 5M

Year: Dec 2015

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Minimum mode Maximum mode
In minimum mode there can be only one processor i.e. 8086. In maximum mode there can be multiple processors with 8086, like 8087 and 8089.
$MN/ \overline{MX}$ is 1 to indicate minimum mode. $MN/ \overline{MX}$is 0 to indicate maximum mode.
ALE for the latch is given by 8086 as it is the only processor in the circuit. ALE for the latch is given by 8288 bus controller as there can be multiple processors in the circuit.
$\overline{DEN}$and $DT/ \overline{R}$ for the trans-receivers are given by 8086 itself. and$DT/ \overline{R}$ for the trans-receivers are given by 8288 bus controller.
Direct control signals $M/ \overline{IO}$, $ \overline{RD}$ and $\overline{WR}$ are given by 8086. Instead of control signals, each processor generates status signals called $\overline{S_2}$, $\overline{S_1}$ and $\overline{S_0}$.
Control signals $M/ \overline{IO}$, $ \overline{RD}$ and $\overline{WR}$ are decoded by a 3:8 decoder like 74138. Status signals $\overline{S_2}$, $\overline{S_1}$ and $\overline{S_0}$ are decoded by a bus controller like 8288 to produce control signals.
$\overline{INTA}$ is given by 8086 in response to an interrupt on INTR line. $\overline{INTA}$ is given by 8288 bus controller in response to an interrupt on INTR line.
HOLD and HLDA signals are used for bus request with a DMA controller like 8237. $\overline{RQ} / \overline{GT}$,lines are used for bus requests by other processors like 8087 or 8089.
The circuit is simpler. The circuit is more complex.
Multiprocessing cannot be performed hence performance is lower. As multiprocessing can be performed, it can give very high performance.
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