Amiga A-500 Plus

Amiga A-500 Plus was developed by Commodore Limited., Released in 1991

The Commodore Amiga 500 Plus (often A500 Plus or simply A500+) is an enhanced version of the original Amiga 500 computer. It was notable for introducing new versions of Kickstart and Workbench, and for some minor improvements in the custom chips, known as the Enhanced Chip Set (or ECS).

Other Informations:

Motorola 68000 CPU running at 7.09 MHz (PAL) / 7.16 MHz (NTSC), like its predecessor
1 MB of Chip RAM (very early versions came with 512 KB.)
Kickstart 2.04 (v37.175)
Workbench 37.67 (release 2.04)
Built in battery backed RTC (Real Time Clock)
Full ECS chipset including new version of the Agnus chip and Denise chip

Commodore created the A-500 Plus for a couple of reasons. The first was cost reduction; minor changes were made to the motherboard to make it cheaper to produce. It was also so that Commodore could introduce the new version of the Amiga Operating system, 2.04.