Acorn Atom
Acorn Atom
The Atom was Acorn's first computer to be aimed squarely at the home market.
Manufacturer
Acorn Computers
Type
Personal Computer
Release date
1980(1980)
Introductory price
120 (in kit form), 170 (assembled)
Discontinued
1983
Media
100KB 5-inch floppy disks,mbt schuhe günstig, Casette tapes
Power
8V, 1.5A unregulated DC,Christian Louboutin Pas Cher, 5V regulated inside.
CPU
MOS Technology 6502 clocked at 1MHz
Memory
2KB RAM (expandable to 12 KB),hogan, 8KB ROM (expandable to 12 KB)
Display
64x64 (4 colors), 64x96 (4 colors), 128x96 (monochrome), 64x192 (4 colors), 128x192 (2 colors), 256x192 (monochrome)
Input
Keyboard
Dimensions
38124164mm
Predecessor
Acorn System 3
Successor
BBC Micro
The Acorn Atom was a home computer made by Acorn Computers Ltd from 1980 to 1982 when it was replaced by the BBC Micro (originally Proton) and later the Acorn Electron.
The Atom was a progression of the MOS Technology 6502 based machines that the company had been making from 1979. The Atom was a cut-down Acorn System 3 without a disk drive but with an integral keyboard and cassette tape interface, sold in either kit or complete form. In 1980 it was priced between 120 in kit form, 170 ready assembled, to over 200 for the fully expanded version with 12KB of RAM and the floating point extension ROM.
The minimum Atom had 2KB of RAM and 8KB of ROM, with a fully loaded machine having 12KB of each. An additional floating point ROM was also available. The 12KB of RAM was divided between 5KB available for programs, 1KB for the page zero and 6KB for the high resolution graphics. The page zero memory (a.k.a. zero page memory) was used by the CPU for stack storage, by the OS, and by the Atom BASIC for variable storage of the 27 variables. If high resolution graphics were not required then 5 1/2KB of the upper memory could be used for program storage.
It had a MC6847 VDG video chip (Video Display Generator), allowing for text or two-colour graphics modes. It could be connected to a TV or modified to output to a video monitor. Basic video memory was 1 KB but could be expanded to 6 KB. A PAL colour card was also available. Six video modes were available, with resolutions from 6464 in 4 colours, up to 256192 in monochrome. At the time 256192 was considered to be high resolution.
It had built-in BASIC (Atom BASIC), a fast but idiosyncratic version,mbt zum Verkauf, which included indirection operators (similar to PEEK and POKE) for bytes and words (4 bytes). Assembly code could be included within a BASIC program, because the BASIC interpreter also contained an Assembler for the 6502 assembly language which assembled the inline code during program execution and then executed it. This was a very unusual,christian louboutin soldes, but also very useful, function.
In late 1982, Acorn released an upgrade ROM chip for the Atom which allowed users to switch between Atom BASIC and the more advanced BASIC used by the BBC Micro. The upgrade was purely to the programming language; the Atom's graphics and sound capabilities remained unchanged, and hence, contrary to some pre-release beliefs, the BBC BASIC ROM did not allow Atom users to run commercial BBC Micro software, since nearly all of it took advantage of the BBC machine's advanced graphics and sound hardware.
The manual for the Atom was called Atomic theory and practice
The Acorn LAN,billige MBT Schuhe, Econet, was first configured on the Atom.
The case was designed by industrial designer Allen Boothroyd of Cambridge Product Design Ltd.
Memory Map
The following is the memory map for the Atom (from 1). Shaded areas indicate those present on the minimal system.
Hex Address
Contents
0000
Block Zero RAM
0400
Teletext VDG RAM
0800
VDG CRT Controller
0900
0A00
Optional FDC
0A80
1000
Peripherals space
2000
Catalogue buffer
2200
Sequential File buffers
2800
Floating point variables
2900
Extension Text space RAM
3C00
Off-board Extension RAM
8000
8000-01FF for mode 0 (512 bytes text)
Video RAM
8000
8000-83FF for mode 1 (1KB graphics)
8000
8000-85FF for mode 2 (1.5 KB graphics)
8000
8000-8BFF for mode 3 (3KB graphics)
8000
8000-97FF for mode 4 (6KB graphics)
9800
A000
Optional Utility ROM
B000
PPIA I/O Device
B800
Optional VIA I/O Device for Printer Interface
C000
ATOM BASIC Interpreter
D000
Optional Extension ROM
E000
Optional Disk Operating System
F000
Assembler
Cassette Operating System
Specifications
CPU: MOS Technology 6502
Speed: 1 MHz
RAM: 2 KB, expandable to 12 KB
ROM: 8KB, expandable to 12KB with various Acorn and 3rd party ROMs
Sound: 1 channel,scarpe hogan, integral loudspeaker
Size: 38124164 mm
I/O Ports: Computer Users Tape Standard (CUTS) interface, TV connector, Centronics parallel printer
Storage: Kansas City standard audio cassette interface
Power: standard 2.1mm power jack connector for 8 volts unregulated DC, providing 5 volts regulated inside the Atom
Note the Acorn 8V power supply was only rated to 1.5 amps, which was not enough for an Atom with fully populated RAM sockets. The Atom's two internal LM7805 regulators (each regulating the + 5V for a section of the digital logic independently) also got uncomfortably hot. Therefore some Atom enthusiasts removed and by-passed the internal regulators and powered their Atoms from an external 5V regulated power supply. Three amps were typically needed for a fully populated Atom.
There has never been a de-facto standard for external 5V connections, but using the same 7-pin DIN connectors as the Atari 800XL allowed an Atari 5V linear power supply to drive an Atom so long as the current was less than the Atari PSU rating (1 or 1.5 amps, depending on model). These are now uncommon, but 5V wall-wart switch-mode power supplies (e.g. for powering USB hubs) capable of supplying several amps are a readily and cheaply available alternative.
External links
Yet another computer museum - Acorn Atom
The Acorn Atom Review
Acorn Atom in FPGA
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Microcomputers by Acorn Computers
Microcomputers
Microcomputer System Atom BBC Micro (aka Proton) Electron Communicator Business Computer BBC Master Archimedes range Risc PC A7000 Network Computer Set-Top Box Phoebe
Operating systems
Acorn MOS Panos Arthur ARX RISC iX RISC OS
Categories: Acorn Computers
Home computers rs
1981 introductions
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