MOS Technology designed two ICs that look very similar, the MCS6530 and the MCS6532.
The 6532 is called RIOT, for RAM I/O and Timer. The 6530 is called RRIOT, for ROM RAM I/O and Timer.
The timer and I/O is (nearly) identical on both IC’s. RAM is 64 byte on a 6530, 128 byte on the 6532.
The ROM is where the big difference is, it is a 1K so called mask programmed ROM. This means the contents of the ROM are determined in the factory.
Besides the ROM also at the factory choices can be made about the Chip and Register Select lines and such.

The 6532 is a general purpose I/O IC and widely used because of its versatility.
Of the 6530 a limited number of variants were made by the factory as I. The 6530 variant is often indicated by a number, 6530-XXX.
Well known variants are the 6530-002 and 6530–003 used in the KIM-1. The 6530-004, called TIM, is used in the Jolt computers. In many Commodore disk drives 6530 variants are used. .

Information on this page:

• RIOT 653X datasheets
• Difference in time count between R6532 and G65SC32
• Known 6530 variants
• 6530 replacement Commodore
• KIM 6530 to 6532
• 6530 hardware emulator in FPGA in 40 pin DIP
• RRIOT testing Breadboard Test for 6530-002
• Commodore Chessmate: 6530-024 RRIOT
• Gottlieb sound board
• TIM 6530-004
  • TIM Superjolt Simulator
  • 6530-004 dissected
    • 6530-004 decapped
  • A Christmas Story About A Tiny TIM
  • THE-RC 41523 CPU-4
  • TIM-1 SBC
  • TIM-2

• 6530 replacement for Commodore drives
• 6530 replacement in the KIM-1 clone and Micro-KIM
• 6530 replacement 6530 in KIM-1
• Commodore Chessmate, Novag II, TEC
• Read out a 6530-009 with a KIM-1 clone
• The TIM 6530-004 based Jolt and Superjolt, designed by Micro Associates and later sold by Synertek Systems
• DATAC 1000, A TIM 6502 SBC

The 6530, nick named RRIOT is quite a special IC in the 65xx family.
Timer, RAM (64 byte), ROM, I/O, Counter in one IC. It has a factory mask programmed ROM and the locations of its I/O and RAM and ROM are determined also in the factory.
The 6530 is found in among others the KIM-1 (6530 02, 6530 03), a Chess system with MicroChess by Peter Jennings (6530 24) and variants are used in Commodore disk drives.

The 6532 has no ROM and RAM size is 128 byte versus 64 in 6530. I/O and timer are functional identical to the 6530. The nickname is RIOT, and it is a general purpose I/O device in the 6502 family. Very popular in e.g. the Atari 2600, and many clone KIM-1’s.

There is a datasheet for an IC called the 6531, RRIOC for RAM ROM I/O Counter. I have never seen it in the wild though, but seen references to pinball machines using it.

A mistery 6530, 021 unknown sofar.

Micro-KIM

The Micro-KIM, see the whole story here,  is another variant of a KIM-1 with the original ROMS and 6532 instead of 6530.

See the complete circuit (version 2009!) here.

Use a KIM-1 (clone) to read out a 6530-009

TODO: add 6530-009 rom bin and assembly