Hello Ruud >My conclusion is that the 6522 works fine as long as you turn of >interrupts. hmmm... thanks for the info. I won't be needing interrupts for this application. The serial port was to save a 7474 chip, but since I need one flip-flop anyway, I can use the other. >> Can you describe this? Aren't all 65xx chips bus /timing compatible? >Yes, they are. But the C64 isn't. The addresslines of the 6522 must be valid >before the ChipSelect signals and PHI2 are activated. With the C64/128 the >VIC-II still commands the addressbus the first xx nanoseconds of the >positive half of PHI2. The trick is to slow down the rising edge of PHI2 >using the DOT-clock. Connect the DOT-clock to the CLK-input of a 74, connect >PHI2 to the data- and CLR-input, tie the PRESET-input to +5 Volt. The >Q-output now delivers the modified PHI2. This explains why my attempts to interface an LCD controller directly to the bus using the 6502 method in the datasheets was such a failure :( Had I known, I would have implemented this simple circuit! Is this part of one of your schematics? Should be part of the hackers-bible. - Nick 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 co-operation. 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 is explicitly the case (C) 2000: Orbital Engine Company (Australia) PTY LTD and its affiliates Message was sent through the cbm-hackers mailing list
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