Eyetech Group Ltd

Amiga Product Notes

Internal AA chipset and external universal models available with or without flickerfixer

Product: MON-17-.26
17" SVGA Colour Digital Display
160MHz, 0.25DP, 1600x1280@75Hz
Mitsubishi Diamondtron tube

Why so many models?
How do you choose which one is best for you?

If you have an Amiga with an AA (AGA) chipset then you have the option to use an internal EZVGA adapter. This is an adapter board that plugs over one of the Amiga chips and joins to a second board which is plugged into the 23-pin video port. The main benefit of this adapter is that it takes the digital signals direct from the 'Lisa' chip (rather than by using the analogue output from the external 23-pin connector). This makes the design less complex electronically and results in a lower cost for the finished product. On the other hand fitting (any) internal unit does require a level of manual dexterity and electrical common sense which is not required by the 'plug and play' design of external units. You should also note that the fitting of an internal unit requires the metal shield of the A1200 to be completely removed, itself a far from trivial operation unless you have already done so as part of a 'towering up' operation. If you have an Amiga other than an A1200 or A4000 then you should use an external model.

Choice 2: Scandoubler or flickerfixer?

A scandoubler simply allows normal PAL (or NTSC) non-interlaced 15KHz (TV displayable) screenmodes to be displayed on a standard PC monitor. If you use software that puts the display into these modes automatically - as most games do - then a scandoubler is probably all you need. (This is also all you need if you are using a retargetable graphics system - such as an Amiga graphics card or the Siamese system - for most of your Amiga work, but need to be able to display native 15KHz screen modes occasionally on a PC compatible screen). A flickerfixer on the other hand allows you to display interlaced 15KHz screens - which are normally unusable on a 15KHz monitor or TV. This gives you twice the vertical resolution and a rock-steady picture for serious applications as well as games. The EZVGA-Mk2 scandoubler can be upgraded to the EZVGA-Plus flickerfixer by adding extra memory chips.

The 'heart' of any Amiga computer - the thing that makes it tick - is a 28MHz oscillator. This is used to govern all aspects of the Amigas operation - including its video output. (In fact the PAL and NTSC versions of the Amiga require slightly different oscillator frequencies to meet the correct TV standards). Lower cost external VGA adapters - like the EZVGA-SE and most competitive products - use their own oscillator to 'replace' that in the Amiga by using the Amigas genlock circuitry. As well as precluding the use of a genlock itself this method can introduce some incompatibilities with some timing-critical expansion units such as accelerators. It also needs to be manufactured with different oscillators for NTSC and PAL Amigas so is not universally interchangeable. The EZVGA-Mk2 and EZVGA-Plus on the other hand use some advanced electronics to derive an oscillator signal from the Amigas video output. This means that both these units will work with all Amigas and will not interfere with the operation of any other peripherals.