MOS Technology 6507: Difference between revisions

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The '''6507''' is an 8-bit [[microprocessor]] from [[MOS Technology|MOS Technology, Inc.]] It is a "cut down" version of their popular [[MOS Technology 6502|6502]]. To reduce costs the 6507 included only thirteen address pins instead of the 6502's sixteen. This allowed the 6507 to address 8 [[KiBkilobyte|KB]] of memory, at the time (1975) considered to be a lot. The omission of these lines allowed the 6507 to come in a smaller 28-pin package, instead of the 40 pins of the 6502.

In addition to the reduced [[address bus]], the 6507 is also unable to service external [[interrupt]]s, but is otherwise identical to the 6502. The 6507 was only widely used in two applications, the bestselling [[Atari 2600]] [[video game console]] and the [[Atari 8-bit family]] [[floppy disk]] controllers for the [[Atari 810|810]] and [[Atari 1050|1050]] drives. In the 2600, the system was further limited by the design of the [[cartridge (electronics)|cartridge]] slot, which allowed for only 4 KiB4KB to be addressed. Most other machines, notably [[home computer]]s based on the [[MOS Technology 650x|650x architecture]], used either the "full" 6502 or extended, rather than cut down, versions of it, in order to allow for more memory.

By the time the 6502 line was becoming widely used around 1980, [[read-only memory|ROM]] and [[random-access memory|RAM]] [[semiconductor]] memory prices had fallen to the point where the 6507 was no longer a worthwhile simplification; its use in new designs ceased at that point, though the Atari 2600 which contained it continued to be sold until the end of the 1980s.