computer science

OpenPIC and MPIC

OpenPIC and MPIC is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand OpenPIC and MPIC rather than just read about it. In short: In order to compete with Intel's Advanced Programmable Interrupt Controller (APIC), which had enabled the first Intel 486-based multiprocessor systems, in early 1995 AMD and Cyrix proposed as somewhat similar-in-purpose OpenPIC architecture supporting up to 32 processors. The OpenPIC architecture had at least declarative support from IBM and Compaq around 1995.

Key takeaways

OpenPIC and MPIC belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect OpenPIC and MPIC to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of OpenPIC and MPIC from memory before moving on to harder problems.

Reference excerpt

In order to compete with Intel's Advanced Programmable Interrupt Controller (APIC), which had enabled the first Intel 486-based multiprocessor systems, in early 1995 AMD and Cyrix proposed as somewhat similar-in-purpose OpenPIC architecture supporting up to 32 processors. The OpenPIC architecture had at least declarative support from IBM and Compaq around 1995. No x86 motherboard was released with OpenPIC however. After the OpenPIC's failure in the x86 market, AMD licensed the Intel APIC Architecture for its AMD Athlon and later processors. IBM however developed their Multiprocessor Interrupt Controller (MPIC) based on the OpenPIC register specification. In the reference IBM design, the processors share the MPIC over a DCR bus, with their access to the bus controlled by a DCR Arbiter. MPIC supports up to four processors and up to 128 interrupt sources. Through various implementations, the MPIC was included in PowerPC reference designs and some retail computers. IBM used a MPIC based on OpenPIC 1.0 in their RS/6000 F50 and one based on OpenPIC 1.2 in their RS/6000 S70. Both of these systems also used a dual 8259 on their PCI-ISA bridges. An IBM MPIC was also used in the RS/6000 7046 Model B50. The Apple Hydra Mac I/O (MIO) chip (from the 1990s classic Mac OS era) implemented a MPIC alongside a SCSI controller, ADB controller, GeoPort controller, and timers. The Apple implementation of "Open PIC" (as the Apple documentation of this era spells it) in their first MIO chip for the Common Hardware Reference Platform was based on version 1.2 of the register specification and supported up to two processors and up to 20 interrupt sources. A MPIC was also incorporated in the newer K2 I/O controller used in the Power Mac G5s. Freescale also uses a MPIC ("compatible with the Open PIC") on all its PowerQUICC and QorIQ processors. The Linux Kernel-based Virtual Machine (KVM) supports a virtualized MPIC with up to 256 interrupts, based on the Freescale variants.

See also Programmable Interrupt Controller (PIC)

References

External links AppleMPIC open source code Archived 2013-05-07 at the Wayback Machine

Worked examples

Example 1 — a first encounter with OpenPIC and MPIC

Start with the simplest possible case. Write down what OpenPIC and MPIC claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to OpenPIC and MPIC before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about OpenPIC and MPIC ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of OpenPIC and MPIC

In research: OpenPIC and MPIC appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses OpenPIC and MPIC in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: OpenPIC and MPIC is common in secondary-school and first-year university syllabi. It links to neighbouring topics AMD platforms, Freescale Semiconductor, IBM computer hardware, so understanding it makes those chapters shorter.
In everyday life: Look for OpenPIC and MPIC outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study OpenPIC and MPIC in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OpenPIC and MPIC means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain OpenPIC and MPIC out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OpenPIC and MPIC in simple terms?

Why does OpenPIC and MPIC matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study OpenPIC and MPIC?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on OpenPIC and MPIC.