Memories, readout

Answer An electronic temperature monitor could be equipped with a bar-code liquid crystal display which could be read by a portable bar-code reader. These devices have a memory so several readings may be taken before they are readout over a telephone modem to a data logging computer. The simplest way to read the acid type would be to post a label that is bar-coded to indicate the acid type. Tire acid quantity could be indicated by an acid level gage using a bar-code display of the level. The aluminum quality could be indicated by displaying a label in bar-code. The amount of aluminum could be determined by weight using a bar-code readout on the scales. 

Lim SJ, Seo J, Park SY (2006) Photochromic switching of excited-state intramolecular proton-transfer (ESIPT) fluorescence a unique route to high-contrast memory switching and nondestructive readout. J Am Chem Soc 128 14542-14547... 

Data acquisition by computer refers to the use of a computer to obtain data (instrument readout values) directly by interfacing to the instrument. These data are then found in the computer s memory, or on disk, and are not necessarily recorded independently on a recorder or in a notebook. 

Dia-Log Co. manufactures p-jump units with optical conductivity detection capabilities. A photograph of the p-jump unit with conductivity detection is shown in Fig. 4.6. Relaxation times of 50 >Lts—100 s can be measured. The conductivity range is 200 S m-1 to 0.05 S m-1, the temperature range is 273-343 K, and a sample volume of 0.5 ml or more can be used with a readout digitizer that has a memory of up to 256 values. It provides automatic data processing and data reduction with a microprocessor. The data can also be evaluated with PET, HP 67, or Wang 600 and 720 hand-held calculators. 

Application of a thermally irreversible photochromic compound in an optical memory medium requires that several conditions should be satisfied. Among them, the development of a non-destructive readout method is a difficult problem. Exposure to light that might be absorbed should be avoided, because it causes destruction of memory. 

Y is then reconverted back to X (erase). Such a write-lock-read-unlock-erase cycle could constitute the basis for an optical memory system with multiple storage and nondestructive readout capacity. 

As discussed at the beginning of this chapter, photochromic systems represent potential molecular level memory devices. A number of problems, however, must be solved for practical applications. A challenge problem is to find systems with multiple storage and nondestructive readout capacity those in which the record can be... 

Their emission bands that excited at the region away from the photochromi-cally active absorption bands could be conveniently regulated in a reversible manner by the photoisomerization of the dithienylethene moieties. This characteristic was useful for the application in fluorescence probes and non-destructive readout for erasable memory media. 

Single readout or continuous read-and-store-in-memory accumulation... 

Random-access readout of the imager is useful for conservation of time and computer memory space since only relevant data is digitized and stored-... 

The digital output can be transmitted to a Hewlett Packard digital printer. A 1205-060 interface makes possible real time or memory mode recording on a rapid option Kennedy magnetic tape recorder for subsequent readout in a Univac computer or a minicomputer. 

The compound 22b has a very large value (704 nm, = 4.3 X 104 M-1 cm-1) in CH3 CN. The molecule has an interesting fluorescence property. Although 22a gives a strong fluorescence, 22b has no fluorescence. Such a fluorescence property change, along with the photochromic reaction, can be potentially used for readout in optical memory.17... 

G. M. Tsivgolulis, and J.-M. Lehn, Photonic molecular devices reversibly photoswitchable fluorophores for nondestructive readout for optical memory, J Chem. Soc. Chem. Commun. 1995, 1119-1122. 

The resolution of the wire per wire readout is restricted to one wire distance, which for many applications is not sufficient. However, the high count rate capability is certainly an advantage where no high spatial resolution is necessary. The encoding time can be made as short as 50 nsec with standard circuits (Schottly TTL or ECL). The storage of the large amount of data in a memory systems however, is not trivial, and is certainly accompanied by high expenses. 

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