The CBM 500 had a 40-column, 300 x 200 pixels display. Contrary to the 600 and 700 it also had two ports for joystick, light pen and paddles.
The CBM 600 was the same as the 500 but had a 80-column display and 256 Kb RAM.
MicroSoft Basic was in ROM. Both models had an option for a second processor (8088 or Z80) to function alongside the standard 6509, the 6509 was then used for I/O, display and keyboard management. They worked under Commodore DOS or CP/M and MSDOS when the computers used the other processors.
The 500 / 600 series was mainly sold in Europe, but a few models are known to have been sold in the United States.
I was just given one european (german) CBM 610 salvaged from destruction by a friend. There is a lot of confusion about these systems. The 610 and 620 models are identical to the american CBM 128-80 and CBM 256-80. The 6x0 computers were advanced 8 bit systems that featured BASIC 4.0+, the very powerful SID sound chip (MOS 6581) and were usually equipped with 128 Kb RAM (a few 256 Kb models were built as well). All 6x0 machines had character graphics only. Aimed at advanced hobbyists and professional users, these systems had no success at all. Yet, in germany the CBM 6x0 computers were actually marketed (I vaguely remeber a few ads in magazines) and almost all units produced in the german plant were eventually sold at very low prices by electronics vendors. The machine I now own was originally purchased by an architect who also owned two PETs. Looks like some people actually used these machines after all.