On Mon, 11 Oct 1999, Larry Anderson wrote: > **also in related news I picked up a 'petunia' board for the PET and an > article on computer music by hal chamberlin, The petunia board has a working > composite video circuit for the PET (will have to check it against Nick > Hampshire's and MICRO's to see which one is employed, if those.) and the > Chamberlin article essentially shows how to make the four-voice music circuit > used in the MTU and the Petunia music boards. I also have a Petunia board, but the sound section has no components. Could you tell me what the chips are at positions 3 and 4 and resistors 9 thru 24? I have used this with the original PET's without the CRTC chip. You can feed the output to a monitor or use a RF modulator to feed it to a TV. With the later PET's with the CRTC it is necessary to change the CRTC parameters to be compatible with the TV. You also have to change a capacitor on the Petunia to compensate for the higher scan rate. I don't have that information handy now. I will have to dig it out. > Back to the tape article... it's from the 3rd issue of the Commodore PET Users > Newsletter from 1979, > it discusses the PET cassete and duplication notes (in general; the recording > characteristics of commodore tapes.)... That is very similar to the article I have, but not identical. It's nice to know where it came from. > Just had to add this tidbit from the same issue, about the PEEKing of the > original PET ROMs... > > Recall earlier I (Jim Butterfield) mentioned that POKE and PEEK aren't > possible on all memory locations for several reasons: > > [snip] > > C. Next on the memory map is the Microsoft BASIC area; locations 49152 to > 57463. This is the memory that recognizes and performs your commands. Changing > the contents of these locations is impossible because it is Read Only Memory > and is actually 'burnt in' at the factory. Therefore, POKing these locations > will simply do nothing. Also, Microsoft requested that these locations return > zeros if PEEKed (for copyright reasons). You can still peek those loactions. It just takes more work. POKE1018,173:POKE1021,133:POKE1022,2:POKE1023,96 POKE1019,lo:POKE1020,hi:SYS1018:?PEEK(2) Where lo and hi are the low and high bytes of the location address. - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tcm.hut.fi.
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