|
Good Evening! Before we enter the museum, I must remind you that food and drink are not allowed in the exhibit rooms, nor is smoking of any kind permitted. The computer's environment must be exactly maintained. Otherwise, the machine will jam-- and destroy two drawers of cards before we can stop it! As we move through the rooms, let me caution you to please remain with your group. Follow me now to our first stop... the card reader exhibit... |
|
Please keep
your children on this side of the velvet rope during our tour. Thank
you! The device you see here provided the system with simultaneous
punched-card input and output. The read section had a
rated
reading speed of 800 cards per minute, although
actual
reading
speed was governed by the stored program. The read feed was equipped
with a device for large capacity loading, called a
file feed.
With the file feed device, the read feed could be loaded with as many as 3,000 cards, which was a drawer and a half in a standard Steelcase card file. This usually gave the operator time enough to run outside and grab a smoke. The 1402 was connected to the 1401 mainframe by several cables the size of your arm. Now if you'll follow me through the door on your right, our next stop will be the line printer exhibit. Some of you might want to use the earplugs you were given at the beginning of the tour. |
|
|
|
LOUD, HUH? HERE, I'LL STOP IT A MINUTE... that's better! The 1403 Printer was another output medium for the 1401 computer. The unit had a rated printing speed of 600 lines per minute. The standard print width was 100, but most folks sprung for the 132 character carriage. Horizontal spacing was 10 characters to the inch. This beast was fast as well as noisy! It could gobble half a box of 14 inch forms before you realized there was a serious flaw in your code. Now, let's follow the cable run to the Tape drives ... |
|
First, let
me caution you about flash pictures. These early tape drives use a
tiny patch of reflective foil to detect end of reel. It was soon discovered
that a flash would send every drive in the facility into rewind and
unload-- so no pictures, please.
14 million BCD digits on a ten and a half inch reel of 1/2 inch tape, ladies and gentlemen! The BCD code was recorded on 7 parallel tracks across the tape. That's right, IBM missed inventing 8 track tape by one lousy track! It's just as well, they weren't interested in consumer electronics market in the 1960's. By the way, the two rectangles you see under each reel were 'air columns' which produced a nearly inertia-less loop of tape that could be instantly backwound so the drive could perform an immediate re-read or re-write in case of error. If you liked our tape drives, just wait'll you see our nifty Disk Drives! |
|
|
|
A moment of reverent silence, ladies and gentlemen. The unit before you is capable of storing 10 Million BCD characters and it's just a Model One! Those disks are two feet in diameter, and rotate at 1200 rpm. At today's cost per megabyte, this jewel would have cost around $2.00. The basic 1405 unit had a single access arm, which traveled vertically to seek one of the 25 disks. Rumors that the design concept was inspired by a Seburg jukebox, are not entirely unfounded. These machines flourished despite the fact that none were sold at Office Depot. Now the moment has arrived... it's time to view the legendary mainframe exhibit... |
|
Shhhhhhhhhh!
You're standing in the presence of one of the earliest widely used
mainframes in the business world. In today's terms, we reckon the clock
speed to be about .086 mHz. These puppies generally had between 4K
and 16K of ram, but could accommodate the tape and disk drives that
we've just seen.
Can you believe it?
The data structure was
called binary coded decimal, or BCD, which was neither binary nor decimal,
but it
did
have a parity bit!
This concludes the formal tour. Please meet us back in the lobby, where you will have an opportunity to ask questions and browse the reading materials. |
|
|
Our goal is to preserve these historic machines that are the very foundation of computing as we know it today. Although we charge no admission, we do accept donations. Pick up a brochure outlining our plans for an exhibit of 402/403 accounting machines, affectionately known as Tabs . Then, when the disreputable looking girl with the worn wicker basket passes among you, dig as deeply as you can. For there are no small dreams... only small budgets. |
Paul White's Home Page
Pioneer programmers: buy a Y2K tee shirt!
Dave Nichols' 1401 site
Email to Paul White