VDUs take residual crude oil from CDUs and refine it at vacuum pressure.
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Both VDUs were found to have leaks in piping and malfunctioning pumps, the sources said.
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VDUs refine residual crude produced by the CDUs, increasing the yield from a barrel of oil.
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Cokers convert residual crude oil from CDUs and VDUs into feedstocks for motor fuels or petroleum coke, a coal substitute.
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VDUs operate at vacuum pressure to refine residual crude oil from atmospheric-pressure crude distillation units (CDUs) into hydrocarbon feedstocks for making motor fuels like gasoline.
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VDUs typically run on residual fuel produced from distilling crude to produce vacuum gasoil which is then used to feed upgrading units that make gasoline and diesel.
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7561 VDUs were memory-mapped display monitors, and not character-based terminals. The tube phosphor was green in colour. The keyboards were separate input/output devices whose data was decoded by the operating software to update the screen display or trigger actions by the system. Security identifiers (Personal Identity Device, or PID) based on magnetically coded pens with a reader at the top right corner of the keyboard unit could be used to provide levels of access-privilege to users. Early 7561/1 VDUs had simple composite-video inputs, while the updated 7561/2 VDU had improved display tubes and interlaced scan. The native screen resolution was 25 lines of 80 characters, but there were options for a 960-character display format. 7502 used a much closer integration between the processor and the display driver circuits. In 7503, the screen updates involved the processor specifying a screen address to the display driver cards, and then firing a sequence of characters to be stored in consecutive locations starting at the specified address.
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The 7502 system enclosure had two levels to include space for the dual, 8-inch floppy disc unit. The interior of the cabinet was covered with acoustic-absorbent foam material to cut the noise from the cooling fans. The maximum connectivity was 8 x 7561 VDU stations and four serial printers, but in the early systems it was necessary to reduce the VDU attachments if floppy disc storage was attached. The rear of the 7502 system carried the connectors for VDUs, modem and serial printers and a set of 8 "engineer's switches" which could be used to input data and set options for "teleloading" software.
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The original server clients were simple text display terminals including Wyse VDUs, and thick clients were generally not used until the increase in PC usage. The original driving force for thin client computing was often cost; at a time when CRT terminals and PCs were relatively expensive, the thin-client–server architecture enabled the ability to deploy the desktop computing experience to many users. As PC prices decreased, combined with a drop in software licensing costs, thick client–server architectures became more attractive. For users, the thick client device provided a more-responsive platform and often an improved Graphical User Interface (GUI) than could be achieved in a thin client environment.
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Its main workload was in the sending and receiving of telex messages but it was also put to work in a wide range of other communications areas including fax. The initial design was for a system that would replace a London commodity broker's antiquated telex room, containing 12 telex machines, with a computer for sending and receiving messages plus a number of VDUs (computer displays) for preparing and editing messages. The resulting Stofor system was an instant hit and many orders were placed when the broker’s associates and competitors saw the system in operation. Additional options such as direct input from dedicated word processors, leased line working and several other features were soon requested and incorporated.
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The keyboard was detachable for the first time and the system had a beige colour scheme (dictated by the colour of the third party VDUs) in place of the black and white appearance of the 400. However, financial problems at SDS were already substantial, and the UK business only ever received a small number of hastily completed machines. In an attempt to bypass these problems Hill produced a clone of the 4000 series computer by reverse- engineering an original model with the aid of a set of paper schematics obtained on a visit to SDS. This was neither approved nor supported by SDS, but Mitchell alone [and not Scheding] made a confidential visit to the UK to help debug the new computer.
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In 1997 (prior to Wi-Fi, Bluetooth and 3G technology), a group of scientists attempted to estimate the number of people reporting "subjective symptoms" from electromagnetic fields for the European Commission. They estimated that electromagnetic sensitivity occurred in "less than a few cases per million of the population" (based on centres of occupational medicine in UK, Italy and France) or up to "a few tenths of a per cent of the population" (based on self-aid groups in Denmark, Ireland and Sweden). In 2005, the UK Health Protection Agency reviewed this and several other studies for prevalence figures and concluded that "the differences in prevalence were at least partly due to the differences in available information and media attention around electromagnetic hypersensitivity that exist in different countries" and that "Similar views have been expressed by other commentators". The authors noted that most of the studies focused on computer monitors (VDUs), as such the "findings cannot apply in full" to other forms of EMF exposure such as radio waves from mobile phones/base stations. In 2007, a UK survey aimed at a randomly selected group of 20,000 people found a prevalence of 4% for symptoms self-attributed to electromagnetic exposure.
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