by Zacharias @ http://inexactitu.de . February 15, 2011 . 1:02PM
1. The ready queue is essentially a linked list of the Process Control Blocks of all processes that have all required resources, except the CPU.
True
Don’t confuse this with the I/O queue.
2. I/O bound programs have a higher frequency of occurrence of large duration CPU bursts.
False
Why are they called I/O bound? Because they don’t need a lot of CPU (otherwise they’d be called CPU-bound)
3. The medium-term scheduler helps reduce the degree of multi-programming by removing partially executed processes from memory.
True
Three types- long term, medium, and short-term. The short term does most of the work, including choosing the next process to execute (by making the virtual CPU a real-life one).
The long term scheduler is in charge what processes can get some memory, thus being able to run.
Call the medium-term dude a “swapper” – there are two kinds of memory issues:
a. swapping – moving an entire program into/out of main memory. Due to low-priority or waiting for slow resources.
b. paging – this means the entire program/process isn’t moved – this is moving a part of it. There are two types of files: one is a “Swapped” file, and another is a page file. Swap files have partially-executed processes. The next time we run a process we don’t want just the partially-executed part. The OS manages the page files.
4. Hardware is a critical feature for preparing the CPU to begin the execution of interrupt servicing; because the state of the interrupted program could be destroyed by the interrupted service routine.
True.
Hardware needs to store at least where the prior process was. We need at least two pieces if info: the PSW and the program counter. The PSW can’t be stored by software.
5. Because of the overhead of context switching, programs that use concurrent processes will always take longer to execute than the same program with a single process.
False.
It takes longer to exec a context switch than not. IF a process blocks for I/O, another process gets to run. A program with multiple processes can perform other operations during I/O – i.e. while another process does I/O another process can do computational work. This allows less total time on the CPU overall, even with the overhead of context switching (especially if the two processes on one program share a lot of context).
6. To achieve high throughput, a multiprogramming OS assigns higher priority to CPU-bound programs.
False.
A compute-bound process will be a worse citizen if they never need to block for I/O. This means more leaving.
7. In general, CPU utilization increases as the degree of multiprogramming decreases.
False.
Programs naturally share the CPU if they’re waiting for I/O. The more multiprogramming, the less time the CPU is idle waiting for resources (i.e. disk access).
8. If we implement the consumer-producer problem with an unbounded bugger, we could expect that producter operations can always complete.
True
The unboundedness has no effect on the consumer.
9. Instructions like a ‘compare’ in assembly language, produce a side effect that saves the value of the arithmetic result in the PSW for use at a later time.
False.
Kind of tricky – Not the value. It does say if >0, overflow, etc, but not the value itself (look in the accumulator).
10. If a user program was able to access the processor status word for read and write, it would be able to ensure that it could keep control of the CPU forever.
True.
The CPU could always be “above” interrupts by default – if a user program is in charge of this it could exist in a state of highest priority.
by Zacharias @ http://inexactitu.de . October 23, 2010 . 5:12PM
I’d save a lot of money if our friends at Square-Enix would stop re-releasing games over and over.
by Zacharias @ http://inexactitu.de . August 21, 2009 . 4:32PM
0800-1300: Sleeping
1320-1500: Coffee (Foldger’s French Roast)
1500-1700: Wawa Iced Tea
1700-1720: Chocolate Milk
1720-1900: Propel (Berry)
1900-2100: Pepsi
2100-0100: Whiskey & Pepsi
0100-0400: Whiskey
0400-0800: Sleeping
by Zacharias @ http://inexactitu.de . August 2, 2009 . 9:38PM
Really, I don’t have a lot to say that isn’t common knowledge: Sprint’s brand is seriously tarnished, customers are leaving in droves, and there’s a lack of “groundbreaking devices” that “change the wireless game.” Sigh, I’ve been hearing it from Sprint’s own customers in quite a few forms for more than a year now.
Last week, I put in my notice, deciding to be a professional student and freelance developer. It’ll be nice to focus on promoting and developing my personal brand in lieu of defending a damaged one.
In the meantime, I’d like to encourage those who continue to work for Sprint. The vast majority of care, retail, and support staff are definitely customer-centric and well motivated – I think that in the longer-term, Sprint will become more of a contender with folks like that working towards that goal.
by Zacharias @ http://inexactitu.de . April 4, 2009 . 9:07PM
The first PC I’d ever used was a Franklin “Clone” that was 99% IBM-compatible. That bastard 1%. After smashing in the then-$50 standard keyboard playing the classic Rogue, my parents surprised me for my 9th birthday with a computer they picked up at a yard sale, one of my very own.
My dad managed to beat the game, with a lot of luck and Merit lights. I’ve yet to accomplish this same goal, even though I’ve wasted like hundreds of manhours in process.
The year, 1992. The computer, an IBM XT 5130.
This model, an IBM 5160, is a little bit newer than the 5130 I had. The “half-height” 5 3/4″ (aka 5.75 to me) drives are very similar in size to the optical drives we still use in ATX-style cases. I hope to actually plug one of these bad boys in (a 5.75 drive), assuming I can find a drive controller card. It’s a .003 Ghz beast running MS-DOS 2.11 (good thing I kept the book!)
The monitors included with many “complete” IBM systems of this era are either monochrome, or at best, CGA (four colors). The two-knob (brightness and contrast), one button (power) setup is simplicity itself. Besides that, there’s not a lot to say about them, except that I’m seriously considering an I(B)Mac.
The XT series computers had some killer peripherals, as well. Most famously are the “clicky” model M series of keyboards IBM developed that gave the feel of their electric typewriters, providing a large metal platform with cork feet for stability. To this day, enthusiasts are buying these keyboards (and the 38 adapters for XT to AT to PS/2 to USB). The mechanical motion makes many membrane-based keyboards (including the quite clicky Blackberry 8350i keyboard I’m using now) feel squishy and unsuitable by comparison.
The yard sale luck held out, when mere months later, I bought a IBM Portable PC for $7. I saved 99.4% on retail! The in-built monitor was monochrome, but if you wanted the four-color action in CGA, you had to plug in an external monitor.
Recalling the feeling of hauling my IBM portable PC (at 40lbs) to school to play around in BASIC (and a little Rogue, natch), I guess I can’t really bitch about a 15″ Macbook Pro weighing around six pounds.
Model: model 68
Introduced: February 1984
Price: US $4225.
Weight: 30 pounds
CPU: Intel 8088 @ 4.77MHz
RAM: 256K, 640K max
Display: 9-inch amber display
CGA graphics, 80 X 25 text
Storage: Two 360KB 5.25-inch disk drives
Ports: 1 parallel, 1 serial, CGA video
OS: IBM PC-DOS Version 2.10 (disk)
Call me nostalgic, but I’ve been thinking long and hard about purchasing one of these old XT computers to relive some early DOS glory. Also, I have a killer rack concept that was inspired by the whole “ikea hacker” movement. (Pending measurement and girlfriend approval. The idea is basically a wardrobe “shell” to be fitted with the necessary shelving and power to be a 4-5 sqft computer museum.
by Zacharias @ http://inexactitu.de . December 25, 2007 . 2:45PM
Thanks so much for reading. (from me and my parents cat)
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by Zacharias @ http://inexactitu.de . October 28, 2007 . 7:29PM
The evidence:
- Woot! is the cheapest retailer on the planet, regardless of whatever it sells.
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by Zacharias @ http://inexactitu.de . October 24, 2007 . 8:51PM
Mac Switcher Advice #1: Do not format your external, internal or flash drives NTFS. Even if you never buy a mac, i may steal it. And I’m fuggin tired of reformatting and moving everything all around the 4 computers, 3 external, and 6 internal hard drives. (more…)
