return to main page

FAQ - Frequently Asked Questions

just starting - May 16, 2017


Goal of this web page: Generate an answer source for visitor Frequently Asked Questions

Table of Contents
Questions with Answers

Open Questions

  • How much does it weigh?
  • What was it used for?
  • How large was the design team?
  • How much did a reel of tape cost?
  • Where do you get cards?
  • How often do we have to ink the 1403 ribbon?
  • Why are the large letters in BigPrint not curved?
  • What is the card code scheme?

Emails & Working Papers
- click here

Questions and Answers

IBM cost to manufacture and to lease an IBM 1401 system - from Robert Garner May 17, 2017
When Chuck [Branscomb] was visiting last week*, I confirmed this $25,000 manufacturing cost for the 1401 entry system, equivalent to the $2500 monthly rental cost target. These figures are equivalent to $250,000 and $25,000/month in today’s currency! (Inflation is 10x over late 50s/early 60s currency.)

Extrapolating to our full-sized tape-based system ($9,000 monthly rental), it’s likely that the manufacturing cost for one of “our" 1401 systems was ~3.6x greater, or $90,000, or nearly $1 million in today’s currency.

If you guys present these figures, at some point someone will ask “How could firms afford such expensive computers!?” (I have an “answer" after perusing a couple 1950s/60s "economics of computers” books. ;-))

Tabular results of above
type of system manufacturing cost - 1958 $
manufacturing cost - 2017 $ 		lease price/month, 40 hrs/week - 1958 $
lease price/month, 40 hrs/week - 2017 $
Minimum System
1,400 char memory 		$25,000
$250,000 		$2,500
$25,000
Our large systems
16,000 char memory
Hardware multiply & divide, etc
Four 729 tape drives 		$90,000
$900,000 		$9,000
$90,000

What store was it sold in? - answer from Stan Paddock, May 16, 2017
There was no store.
IBM would send a salesman to your business and discuss just what you needed.
The IBM 1401 had many options and each option had a cost.
Of the 18,500 IBM 1401 systems built, each one was configured and built for a specific customer.

How much data can a tape hold (in MB)
A good compromise between utility and efficiency is about 10 M (characters), 130,000 80 character cards (6 bit characters, 10 cards/block, 556 BPI)

From Stan Paddock, May 2017 
Tape length 2400 feet
Tape density 556 bits per inch
Inter record gap .750 inches
Card data size 80 characters
Tape blocking factor 10
Data held on one tape 10,526,080 characters
Number of cards images held on one tape 131,576 cards

also, from Allen Palmer - May 18 2017
The tape data question”” how much data can a reel of tape hold is not an easy/perfect answer to give.”

There is a 3/4” inter-record gap between each block of data. This fixed length gap is standard without regard for the amount of data in the record block. So tape compromised of blocks of data containing 2 characters each separated by 3/4” of tape would contain less data than a tape composed of blocks of data composed of 10,000 character long blocks.

Also to issues of density 200/556/800 BPI (Bit Per Inch - Bit = Character) of the tape drive. The reel of tape it self could be used at any of these densities .

Generally the answer was given relative to a box of IBM cards.

also, from Ignacio Menendez - May 18 2017
Ed, when the Docents answer the question about the 729 tape capacity, perhaps it may be a good idea to put it in perspective.....

TAPE/DISK capacity comparison

1959 IBM 1311 can store 2 MB of data
1959 IBM 729 tape stores 10 MB of data

2014 Hardisks store about 2 TB of data
2014 IBM 3592 tape stores 10 TB of data

Still roughly about a 5 to 1 difference.

Today both tape and disk store even more, but I don't have the latest figures.

A much fuller discussion is at TapeBlocking.html by Stan and others

Emails & Working Papers

from Paul Laughton - May 16, 2017
We changed our tactic for getting good questions.
Rather than a big print as a reward, we started to hand out Lincolns.

Some good questions:

How much did it cost?
What store was it sold in?
How much does it weigh?
What was it used for?

Mike and Pat, please feel free to add to this list of good questions that you heard from today's young people.
Paul

from Pat Buder - May 16, 2017
Additional good questions from the groups today:

How large was the design team?
I frequently point out George Ahearn in the restoration team picture on the wall.

How much did a reel of tape cost?

Where do you get cards?

How often do we have to ink the 1403 ribbon?

Why are the large letters in BigPrint not curved?
The concept of having only fixed width fonts and no graphics seems to be foreign to today's kids.

What is the card code scheme?
I use an all characters card to illustrate this.

Pat