From: Scott McDonnell (netsamurai_at_comcast.net)
Date: 2007-04-12 15:54:03
OR gate from diodes: A ------>|---|-----> out | B ------>|---| | / Resistor for voltage drop (1K?) \ / | | \/ Ground Hopefully that stays lined up Scott McDonnell > -----Original Message----- > From: email@example.com > [mailto:firstname.lastname@example.org] On Behalf Of > Antitrack@networld.at > Sent: Thursday, April 12, 2007 9:10 AM > To: email@example.com > Subject: RE: 8kernal/8modules for c64-II ? OR-Gate with diodes > > > > Zitat von firstname.lastname@example.org: > > > Hallo ATT, > > > > > > > Okay. Let me think about this again, Ruud: > > > IF A13=1 then Memorywanted=somewhere between e000-ffff > (KernalROM) > > > ELSEIF A13=0 then Memorywanted=somewhere between a000-bfff > > > (BasicROM) ? > > > > Yep. > > > > > > > So if A13=0 then I must Chipselect. This is not an OR gate, > > > it is an AND gate, isn't it? > > > > No. Write down the 0/1-tables for both and you'll see that you need > > the OR gate. > > You are right, it is an OR gate that I need. > Basically, I'll take the A13 line coming out of the kernal > socket, and OR it together with the Chipselect-Line which > also comes from the kernal socket, and I feed the result of > the OR-gate into the > STROBE-line of the 74LS157. So the resulting three A15, A14, > and A13 lines for the 27c1001 eprom will all be at 0. A16 > will be 1, because A16 is > connected to the Chipselect-Line from Pin11 of the module port. > > Now, some old electrician friend told me that I can use > diodes (1N1418, > is this the right diode to be used ?) to substitute for an OR > gate, but I > cannot remember in what direction the diode must be placed...any hint? > > Yours > ATT > > > -------------------------------------- > Ein Service von http://www.networld.at > > Message was sent through the cbm-hackers mailing list > Message was sent through the cbm-hackers mailing list
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