The Atari Mega ST was the "professionnal" version of the Atari STf.
Atari added the "Blitter", a custom chip designed to perform quick memory moves and increase display speed. The Mega ST had a small battery to hold time and date and a small fan (except for the Mega ST1).
This computer was especially designed to be the cheapest publishing solution (and it was!). The photo shows the Mega ST 4 (4 MB) with a monochrome display (640 x 400), the publishing software "Publishing Partner", the Atari SH 205 hard disk (an old 20 MB 5.25" MFM hard disk) and the Atari SLM 804 laser printer. This printer was really cheap because it had no on-board memory and no page description language, the page was created in the Mega ST memory, then sent to the printer.
The Mega ST had a pretty good success and was replaced by the Mega STe and by the TT.
NAME
MEGA ST
MANUFACTURER
Atari
TYPE
Professional Computer
ORIGIN
U.S.A.
YEAR
1987
CPU
Motorola MC 68000
SPEED
8 mHz
RAM
1 / 2 / 4 MB
ROM
192 KB
TEXT MODES
40 or 80 chars. x 25 lines (bitmapped graphics)
GRAPHIC MODES
320 x 200 / 640 x 200 / 640 x 400
COLORS
16 (320 x 200), 4 (640 x 200), monochrome (640 x 400) among 512