Computer technology: what is a hypervisor?

For me, understanding computer technology requires constant self-tutoring. The tutor defines the term hypervisor.

In my Feb 15 post I explain the idea of a virtual machine. The virtual machine exists atop a hypervisor.

hypervisor (noun):

a program that allows one or more virtual machines (VMs) to function from a single hardware entity. It may host a distinct instance of the same operating system to each VM, or perhaps even different operating systems to different VMs.

The hypervisor exists as a layer above the hardware but below the VMs. The users of the VMs needn’t be aware of the hypervisor.


Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Windows: file permissions: what does Bypass Traverse Checking mean?

Researching file permissions can mean self-tutoring. The tutor relays the idea of Bypass Traverse Checking.

Bypass Traverse Checking (file permission)

This permission allows a user to access a specific file that is not protected, but which resides in a folder the user does not have clearance to examine.

Under the Bypass Traverse Checking permission, the user can navigate to that specific file by its full path designation, without the operating system checking the user’s clearance regarding the containing folder. However, without the necessary clearance, the user cannot simply enter the folder.


Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computer science, technology: what is a virtual machine (VM)?

More technology self-tutoring: the tutor explains the idea of a virtual machine.

virtual machine (abbreviation: VM):

An entity that is accessible via keyboard and screen, like a desktop, and may function, to the user, like a standalone computer. However, the virtual machine resides in a server or computer that may host many others as well.

In a simple case, each employee might use her/his own separate VM at work, but in fact all of the VMs might reside on a single server. (In reality there would likely be at least two servers for back-up purposes.) Yet, each employee experiences their own PC.

On the client side, the actual deployment of the virtual machines might be accomplished via network connectivity and login credentials.


Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Comp sci: asynchronous vs synchronous communication

Tutoring comp sci, you might explain asynchronous communication vs synchronous. The tutor describes them.

Asynchronous communication refers to modes in which the correspondents need not be engaged simultaneously. Email, text messaging, and comment boards facilitate asynchronous communication. In such contexts, the receivers respond at their convenience.

Synchronous communication requires the correspondents to be simultaneously engaged, waiting for incoming messages, reading them as soon as they arrive and responding directly. The motivation for waiting and responding immediately is to continue the stream of communication. A phone call or face-to-face conversation is synchronous communication.


Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Windows 7: the blue screen with white bird near green branch

Trying to repair a computer this weekend has involved self-tutoring. The tutor mentions the beloved “blue screen with white bird near green branch.”

If you don’t know the screen mentioned in the title, you might be lucky. I’ve encountered it after the repair option from F8 during boot. However, it may not appear immediately after selecting the repair option. Rather, the user may have to wait well over half an hour before it appears.

Likewise, the blue screen with the white bird (near the green branch) may persist another 45 minutes – or longer – with no apparent action. However, it eventually can give way to the Startup Repair window. That process can persist for hours, then possibly offer choices, one of which may be System Restore.

That’s how I remember it, anyway.

With either of those screens (blue screen with white bird or Startup Repair), it’s best the user doesn’t hold their breath.


Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computers: why flash drives aren’t vulnerable to magnets (supposedly)

Tutoring, you see flash drives carried around with anything stored on them. The tutor shares some findings about them in relation to magnetism.

I recall holding a flash drive with a magnetic lid, and wondering how it could be so.

Apparently, flash drives hold information using electric charges, rather than magnetism. Two websites tell me that, for that reason, flash drives are not changeable by magnetism – at least, not under normal conditions.

Magnetism and electricity are related. Specifically, a changing magnetic field (for instance, as the magnet moves nearby) can cause voltage in a loop of wire. Therefore, I wouldn’t experiment with a flash drive near a magnet if the data was important.


Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

English, computer science: disk vs disc

Tutoring English, different versions of familiar words are interesting. The tutor shares a find.

In the context of computers, I recall reading disk. “Is it disc?” I would often wonder. Today the matter surfaced, so I looked it up. I got two points of view:


Disk is particularly used in the context of computers, such as hard disk drive (hdd). Disc can be used that way as well, but is the proper way to refer to disc brakes, flying disc, disc jockey, etc.


Disk and disc are interchangeable. Disk jockey is valid.


Collins Essential Canadian English Dictionary and Thesaurus. Glasgow: HarperCollins Publishers, 2006.

Merriam-Webster Dictionary. Springfield: Merriam-Webster, 2004.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Dedicated video memory (Adapter RAM): how to see it with OpenGL Extensions Viewer (realtech)

The tutor tells one way to find how much dedicated video memory your system has. This article describes his experience with Windows 7.

In my February 19 post I discuss the difference between adapter RAM (aka dedicated RAM, vRAM, discrete RAM) vs total video memory. I mention therein that, in my (limited) experience, it seems that adapter RAM can be more meaningful in deciding a system’s capability towards a given graphics application.

My son wanted to use Blender at home, so I had to install it. Looking at its requirements, it needs, among other things, compatibility with OpenGL 2.1 and 512MB RAM.

I watched this video about installing Blender; it pointed me to the program OpenGL Extensions Viewer by realtech. (I believe you can find it here.)

After downloading and installing OpenGL Extensions Viewer, it seems to open automatically. If not, then keying OpenGL in the search box will reveal a choice with a pink icon that says GLview; it’s the one to pick. Then, go to Summary: you’ll see Adapter RAM listed:)


Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computer systems: graphics memory: adapter RAM vs total memory

The tutor shares ideas about adapter RAM (aka dedicated RAM, vRAM, discrete RAM) vs total.

Apparently, adapter RAM is physically dedicated to graphics.

In the context of graphics memory, total memory refers to system RAM available for processing graphics. (From my limited observation, it may not include adapter RAM. Rather, it’s the chunk of the computer’s RAM allocated to graphics presentation.)

I don’t have much experience with video RAM, but from what I’ve seen, adapter RAM appears the more meaningful number when considering if a system meets a program’s requirements.


eHow tech

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.