Conference hydra::amiga_v1

> I did use a logic probe on all the signals on the pheonix expansion and the 
> 68000 in the A500 and found a bunch of signals were at an indeterminate level.
> I'd like to terminate these lines , as the pheonix expansion slots are not

Are you sure they were at an indeterminant level? If you put a probe on,
for example, address line 0 (LSB of CPU buss address) then it will be 
pulsing wildly as the CPU executes instructions. The CLOCK pin will do the
same etc etc.

Most logic probes will not measure the voltage levels, but may give you
some indication of whether the line is hi, low, or pulsing. To properly
determine active logic levels, you need an oscilloscope...

john

    
    The logic probe I used is pretty decent and it does indeed tell you if
    the signal is neither high or low .Ie the red led comes on for high the
    green for low and if neither comes on the level is indeterminate.
    There's also a yellow led that can detect narrow pulses or clocking
    signals etc.
    
    I tried several of the address bits last night and for a brief moment
    at powerup they pulsed wildly but then stopped and the probe told me
    the level was neither high or low and wasn't pulsing ,it was as if
    the 68000 stopped and tristated the address which had no pullups/
    terminations .Anyone know if the 68000 can indeed tristate it's address
    lines ? 
    I haven't put a scope on these lines yet , cos it's such a hassle to 
    borrow stuff from work. I'll probably stick with the logic probe 
    to-night and if I still don't get anywhere I get a scope .
    
    Are the signals on the zorro slots in an amiga 2000 terminated ?
    
    Steve..

    Steve,

�   I tried several of the address bits last night and for a brief moment
�   at powerup they pulsed wildly but then stopped and the probe told me
�   the level was neither high or low and wasn't pulsing ,it was as if
�   the 68000 stopped and tristated the address which had no pullups/
�   terminations .Anyone know if the 68000 can indeed tristate it's address
�   lines ? 

    The 68000 does indeed tristate its address lines (the Motorola version
    does anyway; God only knows what the Hitachi version does ;^).
    When it does "halt", the address, data, and function control lines
    (FC0-2) enter the high-impedance state. You might want to take a look at
    the ~HALT and ~BERR signals. ~BERR can mean an illegal memory access
    request such as the memory board failed to return a ~DTACK (I have no
    idea how Amy does the memory autoconfigure, however). If the 68K
    receives two consecutive bus errors, it will enter the halted state. Or
    when the bus error occurs, the exception handler might put it into a
    stopped state (via STOP instruction).
    
�   Are the signals on the zorro slots in an amiga 2000 terminated ?

    Can't tell you fer shure, but my guess would be yes. My Mon'AMI'Jr. bus
    expander certainly is. It's been running rock solid with a Cltd SCSI
    controller on it, hanging off an A1000. It also ran this configuration
    with the 8up DIP version with no problems.

�   I haven't put a scope on these lines yet , cos it's such a hassle to 
�   borrow stuff from work. I'll probably stick with the logic probe 
�   to-night and if I still don't get anywhere I get a scope .

    Screw the scope; bring home a logic analyzer and then all you have to
    do is hook it up, and reset the 68K with a pulse generator. Then you
    whip out the firmware listings...

    Pete

    Any possibility of a defective SIMM on the 8UP board?  Also, double
    check the configuration jumpers.  I know from experience that you'll
    get a gray screen if the configuration is set wrong.  Note carefully
    how the SIMM sockets are numbered.  They're *not* in sequence.

    
    
    Thanks for the info guys , I did get the 8-up board to work .
    The problem was with the simm's I was using , they were the correct
    type for the board but they had pins which I removed.
    When I inserted the simms into the sockets on the 8-up there were
    several bad connections. I found the only way around this was to use
    the simms with the pins and desolder the simm sockets from the 8-up
    module and solder the simms directly into the 8-up board.
    I had to add each 1/2 meg , reconfigure , test , to be sure everything
    was ok as I went along.
    
    I did find the fault behaviour of the board suprising in that I would have
    thought that if there were problems with one of the simms the module
    would not of prevented the amiga from booting. 
    The only way to get the amiga to boot with the 8-up when it had the bad
    connections to the simms was to stop the 8-up from autoconfiguring.
    Any one explain this ?
    
    Steve..