foresee incorporating as many as 10 million components on one fingernail--sized chip.
Scientists see this as the upper ceiling of the microelectronics revolution because of the
design problems described earlier.
NEW STORAGE MEDIUMS
a. Bubble Memory. Bubble memory, magnetized spots (or bubbles) resting on
a thin film of semiconductor material, was introduced in the late 1970s as a storage
medium. Data are stored by shifting the positions of the bubbles on the surface of the
material. When data are read, the presence of a bubble indicates a zero bit. A bubble
memory module only slightly larger than a quarter can store 20,000 characters of data.
Just as disks represented a more efficient storage medium over magnetic tape, bubble
memory will become an inexpensive and popular alternative to magnetic disks, as
existing production difficulties are overcome. Disks, while more convenient and
accessible than tape, do not lend themselves to storing large volumes of information.
Since large volumes of information can be stored on magnetic bubbles, they will present
a popular alternative to disk storage.
bubble memory: recently developed compact memory device represented by
magnetized spots or bubbles. Bubbles rest on thin wafers of garnet, a
semiconductor material, in a magnetic field. Data on bubble memory are not lost
when the power is shut off.
Figure 4-2. A section of bubble memory magnified 1500 times. Bubble memory
could be a popular alternative to disks one day.