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Main »» Amiga

Table of Contents

What's an Amiga?
In 1985 the Commodore Amiga A1000 was introduced to the world and nothing like it had been seen before. People were amazed. Over the next 15 years individuals, families, and companies purchased millions of Amigas and were introduced to a whole new world of computing.

Since then Amiga users have changed computing for everyone with revolutionary ideas, creative implementations and innovative advancements, all brought about by the elegance and simplicity of the Amiga computer.
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What are 68EC020, 68EC030, 68LC040 and 68EC060/68LC060?
Motorola, the company producing the 680x0 family offers crippled versions of their processors. They are a little bit cheaper than the originals, that's why Commodore decided to build the 68EC020 into the A1200 and the 68EC030 into the A4000/030.

The difference between the 68020 and the 68EC020 is that the latter can address just 16Mb of memory. That's why the A1200 cannot have more that 10 Mb RAM. In most cases you will not notice the difference.

This is not the case for the 68030: The 68030 was the first in the 680x0 series that came with an MMU (Memory Management Unit). Not all the MMU units were functional though, and so some chips say 68EC030 (non MMU), and 68030 (working MMU). There are some important programs depending on an MMU, for example Enforcer (a debugging utility), GigaMem and VMM (programs that implement a virtual memory system) or all current Unix versions. Only the Amiga3000/4000 systems came with an 030/040 as standard. Other Amigas need an additional processor card containing a 68030 or 68040 or 68060 to run these.

The 68040 and 68060 CPUs came with built in MMU units too, but also added a built in FPU (Floating Point Unit). See FPU.
Although in some versions (notably the 75MHz 68060) the FPU and/or MMU is not functional due to the increased temperature the chip runs at. The 68040 and 68060 also came with a separate library for FPU functionality since the 68881/68882 used in conjunction with the 68030 contains more commands than were present in both the later processors FPU units. As such, any non implemented opcodes were emulated in the 68040/68060 libraries.
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What's an FPU?
The first 680x0 processors (upto 68030) could process integers only. Floating point operations had to be emulated by the software. An FPU is a chip (or part of a chip) that can process floating point operations, a mathematical coprocessor.

One separates three FPU types on the Amiga: The 68881, 68882 and the 68040's internal FPU. The 68882 is up to 1.5 times faster than the 68881, because it is splitted in two parts: A conversion unit (the FPU's are using an 80 bit format internally) and the arithmetic unit. The 68040's internal FPU adds a pipeline, but misses the trigonometric instructions of the others. These are still emulated by the software, 68040.library for example.

Special programs (Raytracing, DTP, Mathematics, TeX) are offered in a special coprocessor version which are up to 50 times faster than the original versions.
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Can I use a 3.5' HD in my A1200?
Many people would prefer to use a 3.5" instead of the smaller 2.5" drives as the former are much cheaper. This is possible, but you need a special cable to connect the drive to your IDE controller. Additionally you should put some isolating material between the drive and the main board. Some people report termic problems but I did not notice anything.

Some dealers offer a set which contains the cable, isolating material.

If you are going to install an IDE-harddisk, regardless if 2.5" or
3.5", you should always consider that the it may not work flawlessly, if the drive and ROM-version have not been tested and approved by Commodore. Regarding the A1200, one should also remember that this Amiga has not been designed to hold 3.5" harddisk drives. The 2.5" drives, which are mainly thought for portable computers, may have some advantages (for example in power consumption, heat emission or shock
resistance) that could pay off because of the small keyboard case of the A1200 and the limited power supply. With the larger 3.5" drives, ventilation inside the computer might also be disturbed. If it is necessary to remove some shielding inside the A1200 to make the drive fit inside, even radio interference may occur.

To sum it up: if 3.5" harddisk drives could really be used in the
A1200 without any problems, you could be sure Commodore themselves wouldn't have used the slightly more expensive 2.5" drives in the A1200-HD.
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What is MUI?
MUI is a set of shared libraries which are used to build a
comfortable GUI (`Graphical user interface'). The general idea of MUI is that the programmer determines only the logical structure of the GUI and the look (Font, Size, Windows on Workbench, Public Screen, own Screen, ...) is determined by the user only. From the programmers point of view using MUI is simpler than `gadtools.library' but much more powerful. On the other hand MUI interfaces are slower than GadTools-interfaces, especially on old 68000 machines.

MUI is found in two archives, one for developers only and one for users. Source: Aminet, `dev/misc'.
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What monitors will work on my Amiga 1200/4000?
Monitors can be classified after the horizontal scan frequency they require. TVs, as well as C='s 1084 monitor, need frequencies around 15 kHz. VGA/SVGA need approx. 30 kHz. Multisync monitors can take many frequencies.

In short: You can use any monitor you want with an A1200. BUT:

- If you use a regular VGA/SVGA monitor, you can only use a few display modes (like DblPAL, DblNTSC and/or Productivity). I.e. (320|640) x (256|512|1024) for DblPAL. This is great for Workbench and all "serious" utilities (DTP etc), but don't expect any games to work... they don't use your preferences, just take over the machine and assume a 15 kHz monitor. Also, you cannot utilize the "Early Startup Control" screen (you know, disable cache, and that stuff), which also requires a 15 kHz monitor. Furthermore, VGA monitors don't have speakers. And the VGA-type modes don't support Genlocks. But for a lot of "serious" work, a VGA monitor is quite adequate.

- You already know what happens with a 15 kHz monitor; the flickering in Interlace mode. A small tip: Try to use NTSC instead
of PAL. This increases the refresh rate from 25 Hz to 30 Hz, at the expense of lower vertical resolution (482 lines maximum). The NTSC and PAL modes aren't as bad as many people think. If your monitor has a lot of phosphorous (long afterglow), PAL Laced can be quite OK, and it gives you a resolution of 1448x566 in SuperHiRes. That's the highest resolution currently supported on AGA Amigas, in _any_ display mode.

- A Multisync gives you the best of both worlds. The 1940 and 1942 monitors from C= are quite OK, although rather cumbersome to use... The h/v size and offset must be set manually each time you switch display mode. (1) The 1960 monitor doesn't have this problem, but it's a bit more expensive.

For a VGA/SVGA or Multisync monitor, you'd need a little shiny box which gives you the standard 15-pin "D" connector.

There are other alternatives... like the "AmiVGA" box, which I think is a cheapo version of the Flicker Fixer. (But it's really a shame to use this on an AGA Amiga.)

Also, you can get a VGA monitor, and hook up your TV to the composite or RF port on the Amiga - one monitor for games, one for serious stuff.

NOTE: A patch is available on Aminet for Kickstart 3.0 to do this without manual actions in the file 'os30/util/Monitor30Patch.lha'.
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