I WISH TO THANKS YOU BOTH FOR YOUR KIND SUPPORT!
For Chuck: i got a look to the digital analyzer. It'd be a cool thing. Maybe more useful if you wish to make some accurate adjustment between the signals state looking well what chip could take more late or so on. And then i'd need to build the little interface. Then i'd need to study deeply the Z80 to know what have to happen time by time at each front of clock signal. While i can just understand something of all this, ALL this one is very hard and so far from my each thing i do everyday (job, wife, son, tax, etc.).
Anyway i WISH to thank for ALL your suggestions that internet make so close to me.
Would be more useful to take images from what are the state of all other signals: address bus, data bus and control signals (RD,WR,IORQ???) directly to the CPU and after when they are buffered from the chips you write prior (U83, U65, U78, U79, U82).
I remember just now that some of address bus or data bus seem to me a little strange. I mean some of them maybe was always to high or low level and they not switched fine. I'd have to check better. But if i not remember wrongl they remained in the same level EVEN i taken away the buffering chip like U83 or U65, U78 or U79. I repeat: i have to check again better.
For Pavery: it's natural that BB schematics is very similar to the Kaypro II: Kaypro was born from or maybe has been copied fron the BB1. Then WOW: "What I propose is I give you pin numbers of i/cs to test, and you report back with results" this would be the best for me, but i not have any logic probe. Would be so hard to build one? Where i could find a schematic?
About your affirmation: I would like to confirm the Monitor EPROM is being enabled at bootup. I noted you have inserted a replacement *special* eprom which doesn't access RAM, perhaps just loops on its self? My answer is what Gary E Kaufman [gkaufmanATthe-planet.org] written back to me on the last month 2010: "The Big Board does an interesting trick at startup - it copies the EPROM to DRAM and then does a bank swap. If the dram is not functioning correctly or the swap does not occur it will crash. I have appended the code of an alternate "debug" eprom that uses the video memory only. It will not let you boot, but will let you do a memory test and debug". So this sounds good to bypass RAM problem and check the other parts of the PCB.
An the end: Could you please place the probe on pin 18 of U67 (2716 EPROM) and press Reset. What is the signal? Also, do the same for pin 20 please. Sorry i have not any probe.
Would be more simple to exchange email privately? elazzeriniATinterfree.it
Enrico