6530 6532 TIM – Retro Computing

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:

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.