Integrated Woz Machine

Source: Wikipedia, the free encyclopedia.

Original disk II controller. Integrated Woz Machine implemented all their logic on a single chip.

The Integrated Woz Machine (or IWM for short) is a single-chip version of the

Macintosh
computers.

History

When developing a floppy drive for the Apple II, Apple Inc. co-founder Steve Wozniak felt that the existing models available on the market were too complicated, expensive and inefficient. Rather than use the existing floppy drives from Shugart Associates, Wozniak decided to use the drive mechanism – but develop his own electronics separately for the both drive and the controller.[1][2]

Wozniak successfully came up with a working floppy drive with a greatly reduced number of electronic components. Instead of storing 8–10

6-and-2 encoding.[1]

The floppy drive controller board, the "Disk II interface,"

PROM
, containing tables for the encoder and decoder, the state machine, and some code.

To make it easier to move the controller onto the main board, as in the

Macintosh, Dr. Wendell Sander integrated all these components into one single chip—the IWM.[3]

Application and updates

The IWM is essentially a disk controller on one IC. It was employed in the

MFM-formatted (PC-formatted) floppy disks. In later Mac models, more and more peripheral components were added to the SWIM, until Apple finally phased out floppy drives from the Macs. The floppy controller function still stayed in the chipset for a while, even though the provision of floppy drives for the Macs had already ceased. For instance, the first iMacs still had a floppy drive connector on the motherboard, allowing a floppy drive to be retrofitted by knowledgeable enthusiasts.[4][self-published source?
]

See also

  • Paula (Commodore Amiga)

References

  1. ^
    OCLC 637876171. Archived from the original on 2012-02-12. Retrieved 2013-10-26. [1]
    (NB. Interview with Steve Wozniak, where he describes creating the Apple version of GCR.)
  2. ^ a b "Apple II/II+ Disk Drive interface schematics". Retrieved 2022-07-22.
  3. ^ "Five Different Macintoshes". www.folklore.org.
  4. ^ "iMac Floppy Kit". imac-floppy.com. Corporate Systems Center. 2001-04-14. Archived from the original on 2001-04-14. Retrieved 2020-01-24.

Further reading

Retrieved from "https://en.wikipedia.org/w/index.php?title=Integrated_Woz_Machine&oldid=1213511146"