Antitrack_at_networld.at
Date: 2007-03-30 09:38:18
Quoting ruud.baltissen@abp.nl:
> Hallo ATT,
>
> > since I now have another chipselect-signal which I must
> > somehow process in order to do proper switching.
>
> This ROM is 27128 compatible. Pin 26, addressline 13, is used for selecting
> the Kernal or BASIC part of the ROM. Connect this line to one input of an
> OR-gate, the ChipSelect of the ROM to the other input and the output will
> give the signal you are used to.
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) ?
So if A13=0 then I must Chipselect. This is not an OR gate, it is an AND gate,
isn't it?
And on "real" A13 of my own kernal/module-eprom, I'll have to put my own A13
line there, provided presumably by the same 74LS157 as described in my
schematics.
So the best thing would be to put the "oldA13" to the STROBE line of the
74LS157 as described in my schematics, then connect the output of the 74LS157
to my own (larger) eprom (27C1001). Is this correct?
Thanks for the suggestion of the A13 line tho.
Yours
Antitrack
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