Memory blocking

The SUFIR method has been successfully used in this laboratory for about ten years, implying that its reliability has been frequently checked. The only precaution concerns the timing which must be perfectly stable without disturbance caused by the data storage in alternate memory blocks. Finally,... 

He was born in Macon, Ga., on May 4, 1906, and received his B.S. in chemistry in 1928 and his Ph.D. in physiological chemistry in 1931 at Yale. While at Yale he received research inspiration, which never left him throughout life, from Professor L. B. Mendel, to whose memory Block remained fiercely loyal. Block was a friend to his friends. While he acknowledged his enemies, he ignored them, not permitting them to affect his way of life or his convictions. To him enemies were like booby traps or dangerous leaks in the roof They merely required attention of a strictly technical nature. 

Sequential logic elements, that is, flip-flops and latches, can be inferred by writing statements within an always statement using styles described in Chapter 2. It is best not to synthesize a memory as a two-dimensional array of flip-flops because this is an inefficient way to implement a memory. The best way to create a memory is to instantiate a predefined memory block using a module instantiation statement. 

Don t worry about a question that stumps you even though you re sure you know the answer. Mark it and go on to the next question. You can come back to the stumper later. Try to put it out of your mind completely until you come back to it. Just let your subconscious mind chew on the question while your conscious mind focuses on the other items (one at a time—of course). Chances are, the memory block will be gone by the time you return to the question. 

There is a model that helps us understand the way that memory is laid out. This model is actually called the MS-DOS Memory Map. It was not created all at once but has evolved over time. The first computers to run DOS were based on the Intel 8088 processor. That processor could only access a maximum of 1MB (1,024KB) of memory. So, the first memory map looked like the one illustrated in Figure 3.4. This map allows us to describe how the memory is being used. It is important to remember that this memory map is also called a stack, because for purposes of visualizing concepts the memory blocks are stacked on top of one another. 

A unique characteristic of reserved memory is that various sections of this memory area are typically allocated for special purposes. Table 3.2 lists the common uses for the reserved memory blocks and the addresses they occupy. 

This has the benefit of freeing up conventional memory for use by your programs and is a key concept to memory optimization (which will be discussed later in this chapter). If you don t need expanded memory capability, you can change these lines to turn off EMS but keep the ability to load drivers and TSRs into upper memory blocks (free areas in reserved memory, also called UMBs). To do this, your CONFIG. SYS file must have these lines ... 

Largest executable Largest free upper MS-DOS is resident program size memory block in the high memory 596k (609,968 bytes) OK (0 bytes) area. 

F The free memory switch. Shows all the free memory blocks in the first 640KB and their starting addresses. Also useful in optimizing memory. 

Largest executable program size Largest free upper memory block... 

EMM386. EXE Provides the operating system with a mechanism to see additional memory. The memory space that EMM386. EXE controls has come to be known as upper memory, and the spaces occupied by programs in that region are known as upper memory blocks (UMBs). 

DEVICEHIGHs Command that is used to load the device drivers into upper memory blocks, thereby freeing up space in conventional memory. 

A DOS CONFIG.SYS command that loads the operating system into conventional memory, extended memory, or into upper memory blocks on computers using the Intel 80386 or later processor. To use this command, you must... 

EMM386.EXE Reserved memory manager that emulates Expanded Memory in the Extended Memory area (XMS) and provides DOS with the ability to utilize upper memory blocks to load programs and device drivers. 

C-cross polarization magic angle spinning (CP-MAS) spectra were obtained on a Bruker CXP-100 instrument. A rotor consisting of a barrel of boron nitride and a base of Kel-F was used. Rotor speed was 3.8 kHz. Recycle time was varied from 0.3 to 1 s. A variety of contact times from 0.5 to 3ms were employed. The Hartmann-Hahn condition was set using a sample of hexamethylbenzene. Chemical shifts were measured with respect to external hexamethylbenzene (by storing the hexamethylbenzene spectrum in another computer memory block) but are quoted with respect to TMS. It is assumed that the chemical shifts of hexamethylbenzene with respect to TMS are the same in solution as in the solid state. 

Scopolamine Antimotion sickness, causes sedation and short-term memory block j... 

In the general quadrature scheme one requires two signals to be digitised that differ in phase by 90° but which are otherwise identical. The digitised data from each is then stored in two separate memory blocks, here designated 1 and... 

A simple but instructive implementation of QD (Pajer and Armitage, 1976) is shown in the next figure. With this setup, we can first accumulate the FID s in one memory block in the... 

Since each axis spans the entire chemical shift range, something on the order of a thousand individual FID patterns, each incremented in ti, must be recorded. With instruments operating at a high spectrometer frequency (high-field instruments), even more FID patterns must be collected. As a result, a typical COSY experiment may require about a half hour to be completed. Furthermore, since each FID pattern must be stored in a separate memory block in the computer, this type of experiment requires a computer with a large available memory. Nevertheless, most modem instraments are capable of performing COSY experiments routinely. 

Principle used in multidimensional time-correlated single photon counting. Each photon is routed into different memory blocks according to a control signal read synchronously with its detection. Routing is used to record photons detected by several detectors, to multiplex the measurement at different excitation wavelengths or sample positions, or to classify the photons according to an externally measured parameter. 

Routing was aheady used in classic NIM-based TCSPC setups [56, 57, 58, 59]. Each of the detectors had its own CFD. The CFD output pulses were combined into one common TAC stop signal, and controlled the destination memory block in the MCA. The technique was used to detect the fluorescence simultaneously with the IRF, to detect in two wavelength intervals, and to detect the fluorescence simultaneously under 0° and 90° polarisation. However, because separate CFDs were used for the detectors, the number of detector channels was limited. 

Figure 3.4 shows how the router works in concert with the TCSPC module. The CFD of the TCSPC module receives the single-photon pulse from the router, i.e. the amplified pulse of the detector that detected the photon. When the CFD detects this pulse, it starts a normal time measurement sequence for the detected photon. Furthermore, the output pulse of the CFD loads the channel information from the router into the channel register. The latched channel information is used as a dimension in the multidimensional recording process. In other words, it controls the memory block in which the photon is stored. Thus, in the TCSPC memory separate photon distributions for the individual detectors build up. In the simplest case, these photon distributions are single waveforms. However, if the sequencer is used, the photon distributions of the individual detectors can be multidimensional themselves. 

Fig. 3.4 TCSPC multidetector operation. By the. .channel signal from the ronter, the photons of the individual detectors are routed into separate memory blocks...

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