The court further held that it simply increases the penalty where the victim can be shown to be a police officer engaged in the performance of official duty. In reaching this conclusion, the Court of Appeals relied upon Murphy v. State, 146 Ga. App. 721 ( 247 S.E.2d 186) (1978). In Murphy v. State, supra, the court found that the intent of the legislature was not to create a separate crime of aggravated assault upon a police officer but, rather, to create a separate penalty when the victim of aggravated assault happens to be a police officer.

The evidence adduced at the Jackson v. Denno hearing clearly demonstrates that "[p]rior to interrogation [appellant] was asked to read and sign a form which stated his rights as enunciated in Miranda. . . The state's evidence was that [appellant] read the form and then voluntarily signed it." Murphy v. State, 146 Ga. App. 721, 724-725 ( 247 S.E.2d 186) (1978), overruled on other grounds Bundren v. State, 247 Ga. 180 ( 274 S.E.2d 455) (1981). See also Meyer v. State, 150 Ga. App. 613 (1) ( 258 S.E.2d 217) (1979).

4. Appellant's enumeration of error concerning four requested charges refused by the trial court must fail because none of the requests was supported by the evidence. Murphy v. State, 146 Ga. App. 721 (6) ( 247 S.E.2d 186), overruled on other grounds, Bundren v. State, 247 Ga. 180, 182 ( 274 S.E.2d 455). 5. Appellant's attempt to enumerate as error other aspects of the trial court's charge is unavailing since he neither objected to those portions of the charge at trial nor reserved his right to do so on appeal. Those objections are, therefore, waived.

Accordingly, such evidence was and is irrelevant on the issue of whether the statement was or was not voluntary. See Murphy v. State, 146 Ga. App. 721, 723 (2) ( 247 S.E.2d 186) (1978), overruled on other grounds, Bundren v. State, 247 Ga. 180 ( 274 S.E.2d 455) (1981). The trial court did not err in admitting appellant's statement into evidence.

The trial court charged, however, that knowledge was an essential element of the offense when it charged on the elements of aggravated assault, and by charging that at the time of the assault appellant must have knowledge that he was assaulting a police officer engaged in the performance of his official duties. Glover v. State, 153 Ga. App. 74 ( 264 S.E.2d 554) (1980); Murphy v. State, 146 Ga. App. 721, 726 ( 247 S.E.2d 186) (1978). Hence, we find no error in the charge.

It merely increases the punishment for aggravated assault when the victim is shown to be a peace officer engaged in the performance of his official duties. See Murphy v. State, 146 Ga. App. 721, 725 (5) ( 247 S.E.2d 186) (1978). On this issue, there was no dispute at trial.