|The Photostore Principles of Operation Manual|
|Images of the Photostore|
|Figure 1: The Photostore Cabinets
|Figure 2: The IBM 2321 Data Cell
This device, the IBM 2321 Data Cell, is shown here mostly to allow comparison with the 1360. The Data Cell had 200 strips of wide magnetic tape each about 40 cm long, and there were 10 Data Cells per storage unit. The total capacity was about 4 x 10^9 bits. A detailed description of the 2321's operation and speeds is beyond the scope of this picture caption. Suffice it to say that it was slower and accommodated many fewer bits (10^9) than the Photostore (10^12).
|Figure 3: Another View of the Photostore
|Figure 4: Photostore Chip Storage Unit
An IBM representative and Dr. Sidney Fernbach, Head of the Computation Department, are standing by the opened Photostore chip storage unit - we had two such units. Each held almost 4,000 film chip boxes. They are examining the film used in the chip boxes. This view also shows the crate-like box used to insert boxes of fresh film or previously written chips into the 1360. Each chip box held 32 film chips and each film chin provided 32 data fields. Above the crate-like box one can see 4 trays, each holding about 1,000 chip boxes.
|Figure 5: A Chip Box Tray
John Fletcher is holding a tray used to enter fresh film into the 1360, and a film chip box.
|Figure 6: Cartridge Storage Unit
An unknown woman is standing in front of the Cartridge Storage Unit (one of two) of the IBM 1360, the Photodigital Store. The box she is holding held 32 chips of film, with each chip containing data in a 4 x 8 array of 32 data fields. The tray was used to enter or remove chip boxes. There were about 7,700 chip boxes, for a total capacity of 10^12 user data bits. In addition, there were about a 30% extra bits for error control.
|Figure 7: A Diagram of the Photostore
|Figure 8: A Schematic of the Photostore
|Figure 9: A Schematic of the Photostore Reader
|Figure 10: A Film Chip Box
The film chip box is shown with the top cover removed. The total size of the box is approximately 3 x 1.1 x 1.6 inches. Each film chip held 32 data fields in a 4 x 8 array. One box was very roughly equivalent to one 2400 foot, 8 channel, magnetic tape recorded at 800 bits per inch.
|Figure 11: The Photostore Electron Beam Writer and Developer
||Figure 12: A Film Chip
The 32 data fields on the chip are clearly visible. The chip is approximately 2.75 x 1.38 inches, and had a capacity of ~6.6 x 10^6 total bits, of which there were ~4.7 x 10^6 user data bits.
|Figure 13: Film Chip Data Fields
This is an enlargement of a portion of a film chip. The shadowy object is the eye of a small needle. The tracks are written and read boustrophedonically (look it up).
|Figure 14: Film Chip Data
A much enlarged portion of one data field. Starting with a track of about 4.2 microns width, each data bit is a pair of areas of 8.5 x 8 microns. One of the areas is left clear, and the other is made opaque by the electron beam, modulating a 17.5 megahertz sine wave. For example, a zero bit is a dark area followed by a clear area. And of course, a one bit is just the opposite. As noted in photostore 5, reading and writing is carried out boustrophidonically, and each line carried approximately 30% extra bits for addressing and special error checking and correction. It is no exaggeration to note that IBM's automatic error control and correction was absolutely vital to the successful use of the 1360.