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Conference hydra::amiga_v1

Title:	AMIGA NOTES
Notice:	Join us in the NEW conference - HYDRA::AMIGA_V2
Moderator:	HYDRA::MOORE

Created:	Sat Apr 26 1986
Last Modified:	Wed Feb 05 1992
Last Successful Update:	Fri Jun 06 1997
Number of topics:	5378
Total number of notes:	38326

3644.0. "Pheonix expansion and 8-up problems" by MEALA::COLLINS (STEVE) Tue Apr 03 1990 10:34


I'm having problems with a pheonix expansion and a microbotics 8-up simm
memory card on a A500. On power up the screen goes dark grey and the system 
halts. I've checked the voltages to the pheonix expansion which is powered
from a seperate supply and everything seems ok on that score.

If I disable the slot that the memory module is in from autoconfiguring then
the system will boot up OK but the memory won't be recognised.
Any one have any ideas at what I should look at.

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
terminated but I'm not sure what value resistors to use .Anyone know ?
would this be on an A2000 schematic ?

Thanks for any help ....
Steve

T.R	Title	User	Personal Name	Date	Lines
3644.1		WJG::GUINEAU		`Tue Apr 03 1990 12:43`	14
	> 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
3644.2	cpu halts	MEALA::COLLINS	STEVE	`Tue Apr 03 1990 13:47`	20
	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..
3644.3	Tri-state: ME,NH,VT...	CRISTA::CAPRICCIO	Rub-a-dub-dub,thanx for the grub	`Wed Apr 04 1990 01:38`	36
3644.4		BOMBE::MOORE	Eat or be eaten	`Wed Apr 04 1990 05:19`	4
	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.
3644.5	Working :-)	MEALA::COLLINS	STEVE	`Tue Apr 10 1990 09:41`	20
	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..