Aristocrat relies on a statement from the recent decision of this court in AllVoice Computing PLC v. Nuance Communs., Inc., 504 F.3d 1236, 1245 (Fed. Cir. 2007), where the court stated that in software cases “algorithms in the specification need only disclose adequate defining structure to render the bounds of the claim understandable to one of ordinary skill in the art.” We similarly stated in Medical Instrumentation & Diagnostics Corp. v. Elekta AB, 344 F.3d 1205, 1214 (Fed. Cir. 2003), that “there would be no need for a disclosure of the specific program code if software were linked to the . . . function and one skilled in the art would know the kind of program to use.”

It is certainly true that the sufficiency of the disclosure of algorithmic structure must be judged in light of what one of ordinary skill in the art would understand the disclosure to impart. See, e.g., Intel Corp. v. VIA Techs., 319 F.3d 1357, 1367 (Fed. Cir. 2003) (knowledge of a person of ordinary skill in the art can be used to make clear how to implement a disclosed algorithm); Atmel Corp., 198 F.3d at 1379 (“[T]he ‘one skilled in the art’ analysis should apply in determining whether sufficient structure has been disclosed to support a means-plus-function limitation.”). That principle, however, has no application here, because in this case there was no algorithm at all disclosed in the specification. The question thus is not whether the algorithm that was disclosed was described with sufficient specificity, but whether an algorithm was disclosed at all.

In Medical Instrumentation, we held that the proper inquiry for purposes of section 112 paragraph 6 analysis is to “look at the disclosure of the patent and determine if one of skill in the art would have understood that disclosure to encompass software [to perform the function] and been able to implement such a program, not simply whether one of skill in the art would have been able to write such a software program.” 344 F.3d at 1212 (emphasis in original). We then stated that it is “not proper to look to the knowledge of one skilled in the art apart from and unconnected to the disclosure of the patent.” Id. That is precisely the inquiry the district court performed and that we reviewed above. Here, as in Medical Instrumentation, the patent does not disclose the required algorithm or algorithms, and a person of ordinary skill in the art would not recognize the patent as disclosing any algorithm at all. Accordingly, the means-plus-function limitations of claim 1 lacked sufficient disclosure of structure under 35 U.S.C. § 112 ¶ 6 and were therefore indefinite under 35 U.S.C. § 112 ¶ 2.

IV
Aristocrat was not required to produce a listing of source code or a highly detailed description of the algorithm to be used to achieve the claimed functions in order to satisfy 35 U.S.C. § 112 ¶ 6. It was required, however, to at least disclose the algorithm that transforms the general purpose microprocessor to a “special purpose
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computer programmed to perform the disclosed algorithm.” WMS Gaming, 184 F.3d at 1349. Because the district court correctly held that was not done in this case, we uphold the judgment of the district court.

AFFIRMED.