Hitchhiker’s guide

Anyone that grew up a geek in the late 70’s to early 80’s (ahem) will get the references in this video:

For those of you that are unfamiliar:

The Hitchhiker’s Guide to the Galaxy is a comedy science fiction series created by Douglas Adams. Originally a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, including stage shows, novels, comic book adaptations, a 1981 TV series, a 1984 computer game, and 2005 feature film.

I was most familiar with the video game, which came out about the same time I bought my first computer, the beloved Apple IIc. That might have been in 1986 or so.

Anyway… It is nice to see a new generation of enthusiasts among the current Engineering students.

So long, and thanks for all the fish.

Category 7 Cable

As data transfer technology progresses, so do cable types.  Category 6 UTP copper cable is commonly used today in ethernet installations where 1000BaseT (or gigabit ethernet) systems are required. Cat 6 cable has a certified bandwidth of 250 MHz (500 MHz for Cat6a). Category 6 cable is a newer version of Category 5 and 5e cable wherein the wire pairs are bonded together and there is a separator to keep each pair of wires the same distance apart and in the same relationship to each other.  The four twisted pairs in Cat 6 cable are also twisted within the overall cable jacket.

Category 7 cable is much different from its predecessors.  It has an overall shield and individual pairs are shielded:

Category 7, STP ethernet cable
Category 7, STP ethernet cable

Shields on individual pairs are required to reduce cross talk (FEXT, NEXT). It also requires special shielded connectors called GG45 plugs and jacks.  Pinouts and color codes are the same as gigabit ethernet (Category 5e and 6) however, Category 7 (ISO 11801 Class F) jacks and plugs also have to contacts on the corners of the connector or jack.  This allows better shielding.  A small switch in the jack senses when a category 7 type connector is inserted and switches to the corner contacts, thus keeping jacks and patch panels backwards compatible with Category 5/6 cables.

Category 7 GG45 connectors, jack and plug
Category 7 GG45 connectors, jack and plug

Category 7 cable is rated for 600 MHz bandwidth (1000 MHz for 7a) which translates to 10 GB ethernet.  This was previously the domain of fiber cable.  Copper cable has some advantages over fiber; lower propagation delays, requires less complicated equipment, copper is less expensive than fiber and more durable.  It is nice to have the flexibility to use copper cable on 10 GB ethernet for runs of 100 meters or less.  Longer runs still require fiber.

Category 7 and 7a cable looks remarkably similar to the older Belden multipair “computer cable” pressed into service as audio trunk cable seen so often in older studio installations.

Radio Shack catalog archive

This is a trip down memory lane.  Someone has taken the time to preserve and document Radio Shack, its founding, history and all of the catalogs printed from 1939 to 2005. The website archive is Radio Shack Catalogs.

I remember reading these very catalogs cover to cover, when they came out in the mid 1970’s.  At that time, this stuff looked expensive and in relative dollar terms compared to today, it was.  We had one of these computers in our “Math Lab” in 9th grade:

Radio Shack catalog, TRS-80
Radio Shack catalog, TRS-80

In fact, when I found one of these computers stashed away in the corner of a transmitter site, I had a flash back of Mr. B scowling as yet another student made a mistake plotting x/y coordinates on the backboard.

Tandy TRS-80 Model 4D computer
Tandy TRS-80 Model 4D computer

Ahhh, memories.  Enjoy!