From: Pasi Ojala (albert_at_cs.tut.fi)
Date: 2006-11-06 09:38:35
Hi all, I've been working on a dead C128, and all socketed chips seem to be working. I'm going to try logic analyzer next, but wanted to ask if anyone can suggest something from the symptoms. - Black screen - Action replay inserted -> black screen - CIA's, SID, VIC, VDC, MMU, ROM's do not cause failure in another C128 - Z80 seems to work, as the 128/64 mode goes low when C= pressed during boot and stays high when not. - When measured with a multimeter /NMI is low, LORAM (P0) is low, P4-P5 may remain in input state. (Does CIA2 even cause NMI's in normal boot operation? Is this because the C128 autoboot checks for a drive?) To me this seems to point to either 8502, PLA, or DRAM (maybe less, because AR doesn't change things). Probing the 8502 address and data lines should reveal more. Any thoughts? -Pasi -- "As well try to understand the sun, Perrin. It simply is, and it is not to be understood. You cannot live without it, but it exacts a price. So with women." -- Gaul in The Wheel of Time:"The Shadow Rising" Message was sent through the cbm-hackers mailing list
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