many thanks! > -----Original Message----- > From: William Levak [SMTP:wlevak@cyberspace.org] > Sent: Wednesday, 6 September 2000 11:18 > To: cbm-hackers@dot.tcm.hut.fi > Subject: Re: VIC-20 memory expansion > > > > Here is the layout of the VIC20 RAM expansion: > > VIC 20 74LS11 62256 > > VR/W ----------------------------------------------- WE > RAM 1 ---------------------- 4 > RAM 2 ---------------------- 5 > RAM 3 ---------------------- 3 > 6 ----- s1 ----|---- OE,CS > 8 ----- s1 ----| > BLOCK 1 ------- s2 --------- 9 > BLOCK 2 ------- s3 ------ 10,1,2 > BLOCK 3 ------- s4 ------- 11,13 > 12 ------------------- A14 > +5V -------- s2,s3,s4 > A0-A13 ---------------------------------------- A0-A13 > D0-D7 ------------------------------------------ D0-D7 > > Explanation: > > RAM 1, RAM 2 and RAM 3 are OR'ed together to produce the 3K select. > BLOCK 1, BLOCK 2 and BLOCK 3 are OR'ed to produce the select above 8K. > BLOCK 2 and BLOCK 3 are OR'ed to produce A14 > > s1, s2, s3 and s4 are pairs of DIP switches. > s1 selects between 3K expansion or expansion above 8K. > s2, s3 and s4 select individual 8K blocks. > +5V is provided to pull the unselected 8K block select lines high, > although they are not usually needed > > > - > This message was sent through the cbm-hackers mailing list. > To unsubscribe: echo unsubscribe | mail > cbm-hackers-request@dot.tcm.hut.fi. ---------------------------------------------------------------- PLEASE TAKE NOTE: The contents of this email (including any attachments) may be privileged and confidential. Any unauthorised use of the contents is expressly prohibited. If you have received this email in error, please advise us immediately (you can contact us by telephone on +61 8 9441 2311 by reverse charge) and then permanently delete this email together with any attachments. We appreciate your cooperation. Whilst Orbital endeavours to take reasonable care to ensure that this email and any attachments are free from viruses or other defects, Orbital does not represent or warrant that such are free from computer viruses or other defects. (C) 2000: Orbital Engine Company (Australia) Pty Ltd and its affiliates - 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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