Hallo Bill, > Yes, 74LS257, not 74LS237 > > The fact that the address count always stops at 192 (128+64) suggests > that address bits 6 and 7 on the driver chip are defective (shorted > together). The chip at U25 drives both lines and the physical location of > the drivers are located adjacent to each other on the chip. This a > typical failure of that kind of chip. > > The 74LS258 controlls refresh. Failur of this usually gives a slightly > different address each time. > > Bill Thanks for the info. Makes realy sense. Groetjes, Ruud - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail email@example.com.
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