February 2006

Virtual Machine

The majority of readers will think that IBM entry into personal computing was with the IBM PC in 1981, but my first introduction to IBM’s promotion of personal computing was a few years earlier. I remember attending an IBM personal computing presentation with anticipation, but finding out it was about their VM/CMS capability on their System/370 mainframe. VM stands for virtual machine. CMS is Conversational Monitor System. VM/CMS essentially gave each user their own personal computing environment even though it was on a dumb IBM 3270 terminal in a timesharing mode. I also used IBM’s TSO (Timesharing Option) at the time.

The concept of a 
Virtual Machine has been around for over 40 years. I was reminded about this while reviewing an upgrade to our VMwareVirtual Machine environment at work this week. Another variation that I use today is Microsoft’s Virtual PC where I can run Windows 98 and Windows XP under Mac OSX on my iMac G5. I also run Windows remote to a system at work through a Citrix ICA client and VPN.

wednesday, 22 february 2006 18:00

Analog Computer

Today, it is very rare to use or even see an analog computer in real life. But back in 1968, this was the type of computer that I first used while a Mechanical Engineering student at Michigan Technological University. I don’t remember what class it was for or the problem that I solved on it. I don’t remember what the exact model was either, but it was similar to a Donner Scientific 3100 shown at the Analog Computer Museum web site. I remember using a Problem Board on which we setup our solution and then plugged that into a bigger system.

Today’s digital computers are sequential devices, operating on data one step at a time. It represents data internally in a representation called binary. Thus a single transistor in a digital computer can only store two states, on and off, and requires many transistors to store a number to any degree of precision. Digital computers are programmed through instructions which switch transistors on and off at the lowest level.

An analog computer operates differently than the digital computer. It offers continuous solutions to the problems on which they are operating. All components of an analog computer are part of a complete circuit that operates in parallel. The system is setup with electrical components that simulate portions of a real system. A mechanical spring-mass system may be represented by resistors, capacitors and inductors. When a switch is thrown, the system starts operation and results are measured as voltages and currents.

Note that there were actually mechanical analog computers many centuries earlier. An automobile speedometer is a mechanical analog computer that measures the rotations per minute of the drive shaft and translates that measurement into a display of miles or kilometers per hour.
saturday, 18 february 2006 18:00

Summary of Computers Used

tuesday, 14 february 2006 18:00
What I hope to add to this blog in the future is a little info about computers that I have used in the past. The following is just a list of what I can remember now though I will update the list if I remember more. They are in chronological order: Wolverine adding machine Post slide rule Analog computer IBM System 360 - card reader GE Timeshare TeleType - paper tape DEC PDP 8/e HP 35, 45, 25 calculators IBM System 370 General Automation SPC16 Computervision Control Data 6600, 7600 Apple IIe TI99/4 home computer Commodore 64 IBM TSO/CMS VAX 780 Apollo Control Data 830 IBM PC - DOS DEC Rainbow PC - CP/M Apple Lisa Mac XL Mac 512, Plus, SE, SE30, IIci Compaq PC - Win3.1 iMac HP Unix workstation Toshiba laptop - Win98 Compaq, Dell - Windows 2000 Sun workstation - Solaris Power Mac G4, G5 - OSX Virtual PC - Windows XP eMac, iBook iMac G5

iMac G5 VESA Stand

iMac G5 VESA Stand
saturday, 11 february 2006 18:00

Seeing that I started this blog with a picture of my "first" computer, I figured I would go next to my latest and then fill in with others that I have worked with over the years.

Shown here is my 20” iMac G5 containing a 2.0 GHz PowerPC G5 processor, 1.5 GB of DDR SRAM memory and 250 GB internal hard drive. It has built-in Airport and Bluetooth wireless capability so the only cable that it needs to run is the power cord. I have it connected up to a AC-powered DYNEX hub containing 3 USB and 3 Firewire ports which is then connected to a number of other peripherals. I have a 250 GB LaCie Firewire hard drive that is my backup, completely mirroring my internal drive. I also have a Maxtor 200 GB USB hard drive that is used for backup of other computers as well as video data.

My keyboard and laser mouse are wireless from Logitech with the wireless transmitter connected to the USB portion of the hub. This means that I have no wires to contend with when using them on my old LazyBoy recliner. The laser mouse works great on the arm of the chair without any need for a mouse pad.

Also connected to the hub is a Canon flatbed scanner for capturing paper docs and an EyeTV 200 converter, which allows me to watch and record cable TV on the iMac. I occasionally connect an iPod mini, a Canon PowerShot A85 digital camera, a Canon ZR-10 video camera and a Blackberry 7250.

Undoubtedly, you noticed the special setup on my homemade computer stand. This is actually my second-generation stand; the first was used to mount a 17” LCD display connected to a PowerMac G4. In this case, the 20” display contains the complete computer. (See the Apple store for the original desktop stand that I removed.)

The iMac had a VESA standard mounting option that I have bolted to a 2” steel pipe stand. The rest is regular PVC plumbing pipe, the main members of 2” pipe and supporting members 1 1/2”. The original stand was made all of 1 1/2” pipe, but deflected too much with the 25 lb weight of the iMac. The vertical portion of the pipe has a steel insert that I happened to have in my collection. This allows the arm to swivel. The last piece is the base made out of 2x6s and plywood with a corner hole and PVC wedges to hold the vertical pipe secure. The weight of the wood and the LazyBoy are enough to make this setup very steady.

I also have a portable PVC stand that I can use on a desktop and another portable floor-based design under construction. I have deflection problems with the portable floor-based system and need to try larger pipe on the lower portion.

This iMac has a little history before me. I bought it from Scott Sheppard, Editor-In-Chief – OSXFAQ, back in August. Scott had some excess inventory from his office that he posted on his email list. I jumped on the opportunity and saved $200 for a new system, sealed in the original box. Check out Scott’s web site, Tip-of-the-Day and email list at http://www.osxfaq.com