RAMAC Restoration Web Site

Visiting again? New Items and Updates

This site presents information about:

IBM Archives
  1. IBM's RAMAC 350, the world's first Random Access Magnetic Disk Drive
    the ancestor of the hard drive in your computer - with 5 million characters.
  2. The restoration of the storage section of one of these machines.
  3. The 305 RAMAC was a computer system that contained the 350 RAMAC unit.
(Left) "Our" RAMAC. on loan from IBM
image from the Magnetic Disk Heritage Center

According to http://www-03.ibm.com/ibm/history/exhibits/storage/storage_350.html, over 1000 *305* computers (which utilized these storage devices) were shipped before production of the *305* ended in 1961.

Similar/identical mechanisms but with different interface electronics were also available for the IBM 650 and the IBM 1401.


via Dave Bennet 		(Right) RAMAC and a DC-7. Date on back of photo is "Fall, 1957"
Two mutually exclusive? comments
- "Beautiful Atom Fair?" ?Atoms of Peace? Photo at Amsterdam? airport.
- trip to the Brussels World's Fair in 1958.
- photo from Dave Bennet, scanned by Robert Garner
and links to YouTube videos: IBM 305 RAMAC publicity release,
And another IBM 305 film, different from above. Spotted by Herbert Kanner

a subset of the above, pouring oxide on a disc. Spotted by John Van Gardner

*Very* recent events: - of a much longer restoration history -
2006

June, July, August, October, November
2007
January, February, March, May, June, July
2008
January


Other contents:

- Disclaimer
- Goals
- Introducing the RAMAC
- Useful links, ...
- Documents on line 		- Control Overview
- Pictures
- Interesting Info
- Contact Info
- RAMAC in the news 		- Some RAMAC patents

Disclaimer
This web site is *not* official web site anything.

This link points to the official web site of the Magnetic Disk Heritage Center which has a great deal of technical and historical information on the RAMAC.

One might call this web site (the one you are viewing) a working/current status web site.

About 2 years of restoration work has been accomplished before this web site started. :-))

Current goal: present the working RAMAC to interested viewers,

probably at its current location in Computer History Museum, MountainView, California.

Future goal: present the RAMAC in a future museum located at the location of its development - 99 Notre Dame Ave, San Jose, CA

Magnetic Disk Heritage Center

Introducing the RAMAC
RAMAC characteristics - and fun facts

Useful links

Restoration History of this RAMAC

Other existing RAMACs and RAMAC restorations

This web site is presented as a learning aid to its owner, who wants to join this ongoing restoration effort.
I never worked on a RAMAC, but I did install and maintain this "second generation" product from General Electric Computer Department in 1963, and did see a working RAMAC at G.E. Large Appliance Division in Louisville, Kentucky in 1963.

Documents on line -

Control Overview

  • The upper left tapped pot shows the track (horizontal) setpoint and position feedback.
  • The arm bearing the read write erase head(s) is upper right, showing a disk detent to prevent vertical movement while arm is carrying heads onto selected disk.
  • The lower left tapped pot shows the disk (vertical) setpoint and position feedback
  • The servo/clutch Amplifier, motion select clutches, tach, and drive capstan (for both vertical & horizontal) is lower right

Pictures:

The red thing is a very noisy aircompressor with regulator. The black tank is an accumulator? to smooth?? 50 psi air is used to operate detents, "lower" the heads using 3 little pistons, supply air to the six little holes in the head to fly the head maybe 0.0003 inch off of the oxide on the disk
Part of the drive train to select disk and track.
The left and right cylinders are electro-magnetic clutches to transfer power from the electric motor (not shown - below the picture, through the hard rubber bevel (like a slippable bevel gear, to drive the selected clutch. The clutches are counter rotating with a common shaft. If you want the shaft to go in one direction, select one clutch, the other clutch will drive in the other direction. (The carbon brush assembly to conduct electricity to the internal magnet is visible in the upper left corner of the left clutch.)
Potentiometer to sense the position of the arm/head assembly on a disk.
This unit has the normal end taps plus 5 more taps to aid precision location of the head among the 100 data tracks. Unfortunately, one of the five extra taps is open. "Todd" says " I worked in the plant in Ramsey, NJ in the 60's. The potentiometers were molded with plastic track and metal connections. Sometimes the plastic did not make a good contact with the metal. We would then paint a connection with silver paint and bake for about half an hour.
It you open the unit, you probably will see that the outside of the track has been ground away to make the exact resistance specs of the unit.
These are the plugs from the RAMAC, and the sockets and wires the Santa Clara students added to connect their board. The original RAMAC connectors are used. Apparently finding the matching connectors was a challenge.
This is the area of the Santa Clara drive boards with plugs and cables to the RAMAC. Note that the plugs and sockets are much easier to find than the connectors at the RAMAC end.
This is the drive circuitry make by the Santa Clara students, , to drive the RAMAC seek mechanism. A manual switch to operate the head lowering air switch is off screen. A PIC, running BASIC, was used to:
- compute velocity from successive potentiomenter readings
- "close the servo loop" ie. sense loop error and output corrective voltages (currents) to the clutches
Using this method, they achieved a seek time of about 10 seconds
Joe Feng amplifies the about 80,000 bit rate signal from the RAMAC read head (about 40 millivolts) by 2 and uses this scope to:
- oversample by about 12
- digitize and captures the result
He then down loads the captured result to a PC for analysis, decoding, what ever :-))
Joe Feng sent this image "... of ABS of one of the RAMAC heads, taken by Terry Whittier of HGST."
"The scratches are clearly from the fabrication process, and not due to damage from the disk, since they are at an angle to the direction of travel. The R/W element is on the left, and the E head is on the right. The surprise is that the E gap is shorter than the R/W gap."
Ah - the "E gap" is the gap in the erase magnetic structure, on the right.

Interesting Info from Dave Bennet July 4th 2006

There was a 353 and a 355 version of RAMAC. I gather that 355 was the version that went on 650 and if so I'm not sure of the differences from 650. My guess would be that it might have a different data format and whatever other changes were necessary to attach to 650. The 350 data I/O was sequenced by a drum file in the processor unit. 650 may have done it another way.

The other version, I guess it was 353, was the STRETCH version, which had one head per disk surface. Early ones still had air pressurized heads, which took a LOT of compressed air. Later ones had flying heads. CHM has a STRETCH RAMAC which came from Livermore Lab, but someone discarded the head arms because they were supposedly rusty. In so doing they discarded the most interesting part of the machine. Dave

Contact Info - "in no particular order"

Al Hoagland AHoagland at gmail dotty com , cell 408-348-6647
Dave Bennet KVXW89A at prodigy dotty net , 831-688-6372, cell 408-892-0272
Dick Oswald DOswald at psdc dotty com , 408-295-0094, work 408-557-4452
Ed Thelen ed at ed-thelen dotty org , 510-742-1146, cell 510-828-7673
Jack Grogan jackg1936 at aol dotty com , cell phone 408-234-1936
Member of the 1405 development team from day one to first customer ship. I wrote most of the 1405 diagnostics that ran on the 1401; circa 1960
Joe Feng Fengjs at juno dotty com , 408-365-7942
Herky Hanson CPHanson at aol dotty com , 408-225-0458
Pat Connolly PatConnolly at gmail dotty com , cell 408-309-6693
Thomas E. Gardner t.gardner at computer dot org ,

Some RAMAC patents

- 1970 IBM patent announcement - .pdf, 1.5 megabytes
- US03503060__.pdf - .pdf, 5.9 megabytes - filed Dec. 24, 1954, granted March 24, 1970
- US03134097__.pdf - .pdf, 5.9 megabytes - filed Dec. 24, 1954, granted May 19, 1964

"Prior Art"
- 2690913.pdf - Magnetic Memory Device - 500 K Bytes by J. Rabinow - filed March 14, 1951

Website started June 8, 2006
Updated through Feb 27, 2008

If you have corrections or suggestions, please send e-mail to Ed Thelen (ed@ed-thelen.org) -