In 1991, Atari planned to replace the old STe computers.
They realized then the "Sparrow Card", which was a development card plugged into the 68000 slot of an Atari 1040 STe.
The "Sparrow Card" had one of the main feature of the future FX-1 / Falcon 030 computers : it was a dual CPU board. It used a Motorola MC68030 and a Motorola DSP 56K.
The "Sparrow Card" used a 16 MHz 68030, a 16 MHz 68882 (arithmetic coprocessor) and a 32 MHz DSP 56K with 24 KB of static RAM.
Later, when Atari made the first fully functionnal computer from this prototype board, they planned to name it "FX-1", they eventually name it "Falcon".
The Atari FX-1, or "Sparrow", is also a prototype machine. Actually, it is almost a Falcon030. It has all its features except its true color mode (not fully implemented in the FX-1) and the PCM sound channels (12 bit instead of 16 in the Falcon).
These computers used the Atari Mega STe TOS (2.06) slightly modified to cope with the new graphic modes. This TOS version had the number 2.07 and was replaced in the last Sparrow models with the TOS 4.0 (The Falcon used TOS 4.01 in the earlier models, then the 4.04 and finally the 4.92 (never released)).
Atari produced less than 100 of these machines. They were built with sample spare parts and were used by developpers to write software for the future Atari Falcon.
Curl Vendel says :
Originally, the Sparrow/FX-1 had a better graphics processor, but it was incompatible with most software. A newer processor was built that was more compatible (yet slightly crippled) with ST/e software.
Just a small correction to the comments on the name badge page. The eventual Falcon case was a lighter colour than the ST, and though the keyboard looks the same as the FX-1, the key lettering is different.
On the FX-1, the key lettering is yellow, with red lettering on the function keys, but the Falcon has white lettering. The Falcon on the Falcon030 page here is in ST colours, only a few of these exist and were shown at trade shows just before the Falcons launch.