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Amiga 500

The Amiga 500 known as the A500, is the first low-end Commodore Amiga 16/32-bit multimedia home/personal computer. It was announced at the winter Consumer Electronics Show in January 1987 – at the same time as the high-end Amiga 2000 – and competed directly against the Atari 520ST. Before it shipped Commodore suggested a list price of US$595.95 without a monitor. At delivery in October 1987 Commodore announced that the machine would carry a US$699/£499 list price. In Europe the Amiga 500 was released in May 1987. In the Netherlands it was available from April 1987 for a list price of 1499 HFL; the Amiga 500 represents a return to Commodore's roots by being sold in the same mass retail outlets as the Commodore 64 – to which it was a spiritual successor – as opposed to the computer-store-only Amiga 1000, as well as being another computer whose keyboard is included in the same case. The original Amiga 500 proved to be Commodore's best-selling Amiga model, enjoying particular success in Europe. Although popular with hobbyists, arguably its most widespread use was as a gaming machine, where its advanced graphics and sound were of significant benefit.

It has been claimed that over 6 million A500s were sold worldwide, according to Commodore UK, the entire sales of all Amigas in both Europe and the USA were 4-5 million. While not the first computer to have an open architecture, the Amiga is considered due to its expandability as one of the early examples. In October 1989, the Amiga 500 dropped its price from £499 to £399 and was bundled with the Batman Pack in the United Kingdom which included the games Batman, F/A-18 Interceptor, The New Zealand Story and the bitmap graphics editor, Deluxe Paint 2. Included was the Commodore A520 RF Modulator, an adaptor which allowed the A500 to be used with a conventional CRT television set, via its RF antenna socket. In late 1991, an enhanced model known as the Amiga 500 Plus replaced the original 500 in some markets; the Amiga 500 series was discontinued in June 1992 and replaced by the specified and priced Amiga 600, although this new machine had been intended as a much cheaper model, which would have been the A300.

In late 1992, Commodore released the "next-generation" Amiga 1200, a machine closer in concept to the original Amiga 500, but featuring significant technical improvements. Despite this, neither the A1200 nor the A600 replicated the commercial success of its predecessor, as by this time, the popular market was definitively shifting from the home computer platforms of the past to commodity Wintel PCs and the new "low-cost" Macintosh Classic, LC and IIsi models. Outwardly resembling the Commodore 128 and codenamed "Rock Lobster" during development, the Amiga 500 houses the keyboard and CPU in one shell, unlike the Amiga 1000, it utilizes a Motorola 68000 microprocessor running at 7.09379 MHz. The CPU implements a 32-bit model, has 32-bit registers and 32-bit internal data bus, but it has a 16-bit main ALU, uses a 16-bit external data bus and 24-bit address bus, providing a maximum of 16 MB of address space; the earliest Amiga 500 models use nearly the same Original Amiga chipset as the Amiga 1000.

So graphics can be displayed in multiple resolutions and color depths on the same screen. Resolutions vary from 320×200 to 640×400 for NTSC and 320×256 to 640×512 for PAL The system uses planar graphics, with up to five bitplanes allowing 2-, 4-, 8-, 16-, 32-color screens, from a palette of 4096 colors. Two special graphics modes are available: Extra HalfBrite, which uses a 6th bitplane as a mask to cut the brightness of any pixel in half, Hold And Modify which allows all 4096 colors to be used on screen simultaneously. Revisions of the chipset are PAL/NTSC switchable in software; the sound chip produces four hardware-mixed channels, two to the left and two to the right, of 8-bit PCM at a sampling frequency of up to 28 kHz. Each hardware channel has its own independent volume level and sampling rate, can be designated to another channel where it can modulate both volume and frequency using its own output. With DMA disabled it's possible to output with a sampling frequency up to 56 kHz. There's a common trick to output sound with 14-bit precision that can be combined to output 14-bit 56 kHz sound.

The stock system comes with AmigaOS version 1.2 or 1.3 and 512 KiB of chip RAM, one built-in double-density standard floppy disk drive, programmable and can read 720 KiB IBM PC disks, 880 KiB standard Amiga disks, up to 984 KiB using custom-formatting drivers. Despite the lack of Amiga 2000-compatible internal expansion slots, there are many ports and expansion options. There are two DE9M Atari joystick ports for stereo audio. There is a floppy drive port for daisy-chaining up to three extra floppy disk drives via an DB23F connector; the then-standard RS-232 serial port and Centronics parallel port are included. The power supply is; the system displays video in analog RGB 50 Hz PAL or 60 Hz NTSC through a proprietary DB23M connector and in NTSC mode the line frequency is 15,750 Hz HSync for standard video modes, compatible with NTSC television and CVBS/RGB video, but out of range for most VGA-compatible monitors, while a multisync monitor is required for some of the higher resolutions. This connection can be genlocked to an external video signal.

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Mabrur Rashid Bannah

Mabrur Rashid Bannah is a Bangladeshi writer and television director who has directed more than 50 telefilms and TV series. Bannah began taking pictures in class 8. For many years he worked as a contributing photographer for the daily newspaper Samakal, he began making short films with a handycam. At the University of Development Alternative he studied film in the Department of Communication and Media Studies, he wrote his thesis on Tareque Masud's Matir Moina. To gain practical experience he worked as Iftekhar Ahmed Fahmi's assistant director. Bannah made his directorial debut in December 2011 with the broadcast on NTV of telefilm Flashback, co-directed by Imraul Rafat. In addition to co-directing the film, Bannah wrote the screenplay, it was six months until he directed his second telefilm, The Fortune on NTV. Bannah said the film "turned on his fortune". Since 2012 he has directed TV series, he has made around 11 telefilms with the collaboration of writer Rajiul Huda Dipto. On 22 May 2015, after five years together, Bannah married Sania Afrin, a lecturer at United International University

Tachyon (software)

Tachyon is a parallel/multiprocessor ray tracing software. It is a parallel ray tracing library for use on distributed memory parallel computers, shared memory computers, clusters of workstations. Tachyon implements rendering features such as ambient occlusion lighting, depth-of-field focal blur, shadows and others, it was developed for the Intel iPSC/860 by John Stone for his M. S. thesis at University of Missouri-Rolla. Tachyon subsequently became a more functional and complete ray tracing engine, it is now incorporated into a number of other open source software packages such as VMD, SageMath. Tachyon is released under a permissive license. Tachyon was developed for the Intel iPSC/860, a distributed memory parallel computer based on a hypercube interconnect topology based on the Intel i860, an early RISC CPU with VLIW architecture and. Tachyon was written using Intel's proprietary NX message passing interface for the iPSC series, but it was ported to the earliest versions of MPI shortly thereafter in 1995.

Tachyon was adapted to run on the Intel Paragon platform using the Paragon XP/S 150 MP at Oak Ridge National Laboratory. The ORNL XP/S 150 MP was the first platform Tachyon supported that combined both large-scale distributed memory message passing among nodes, shared memory multithreading within nodes. Adaptation of Tachyon to a variety of conventional Unix-based workstation platforms and early clusters followed, including porting to the IBM SP2. Tachyon was incorporated into the PARAFLOW CFD code to allow in-situ volume visualization of supersonic combustor flows performed on the Paragon XP/S at NASA Langley Research Center, providing a significant performance gain over conventional post-processing visualization approaches, used previously. Beginning in 1999, support for Tachyon was incorporated into the molecular graphics program VMD, this began an ongoing period co-development of Tachyon and VMD where many new Tachyon features were added for molecular graphics. Tachyon was used to render the winning image illustration category for the NSF 2004 Visualization Challenge.

In 2007, Tachyon added support for ambient occlusion lighting, one of the features that made it popular for molecular visualization in conjunction with VMD. VMD and Tachyon were adapted to support routine visualization and analysis tasks on clusters, for large petascale supercomputers. Tachyon was used to produce figures and the Nature cover image of the atomic structure of the HIV-1 capsid solved by Zhao et al. in 2013, on the Blue Waters petascale supercomputer at NCSA, U. Illinois. Owing in part to its portability to a diverse range of platforms Tachyon has been used as a test case for a variety of parallel computing and compiler research articles. In 1999, John Stone assisted Bill Magro with adaptation of Tachyon to support early versions of the OpenMP directive-based parallel computing standard, using Kuck and Associates' KCC compiler. Tachyon was shown as a demo performing interactive ray tracing on DEC Alpha workstations using KCC and OpenMP. In 2000, Intel acquired Kuck and Associates Inc. and Tachyon continued to be used as an OpenMP demonstration.

Intel used Tachyon to develop a variety of programming examples for its Threading Building Blocks parallel programming system, where an old version of the program continues to be incorporated as an example to the present day. In 2006, Tachyon was selected by the SPEC HPG for inclusion in the SPEC MPI 2007 benchmark suite. Beyond Tachyon's typical use as tool for rendering high quality images due to its portability and inclusion in SPEC MPI 2007, it has been used as a test case and point of comparison for a variety of research projects related to parallel rendering and visualization, cloud computing, parallel computing, runtime systems, computer architecture, performance analysis tools, energy efficiency of HPC systems. Visual Molecular Dynamics Tachyon Parallel/Multiprocessor Ray Tracing System website Tachyon ray tracer John Stone's M. S. thesis describing the earliest versions of Tachyon