[Techtoolslist] Poss. dumb 9010 query

[Martin White]

Program ram (a single 6116 on the SCPU board) can't be tested at all. It 
simply can't talk to it properly, nor the roms (so it would seem anyway - 
wander if that's anything to do with the CTC?). It comes up with BTS FF error 
for any address in program ram - a single 6116. This is not a fault though, 
it's just the way it is. It does it on all 15 boardsets i'm working on, even 
the ones where the game works fine and there are just issues with the SSIO 
board!

The staging ram (2 x 2114 on the vid gen board) have the BTS 08 error, 
however, the problem doesn't lie with anything on the vid gen board since you 
can disconnect that board completely and still get the BTS 08 error when you 
try to do the test on the background ram.

I haven't tried removing all the roms to see if they're fouling the busses at 
all, but they shouldn't be since they're known good roms. Could be sockets i 
guess?

So you see, i'm pretty sure i'm looking at a buffer / interface problem, just 
wanting to confirm if it's the address lines or the data lines for the 
particular Fluke error message. I'm pretty sure it's the data lines.

However, i'm not seeing any bit tied high or low, so maybe i'll just replace 
the 245 anyway for the fun of it, and maybe the cpu socket, and i guess i can 
always try removing the pull-up resistor pack on the data lines and see if 
the problem goes away before putting them back of course!

Cheers all...

Martin.

On Wednesday 06 July 2005 01:50, John Robertson wrote:

> How about trying to test RAM in a different IC?

>

> If you have three banks of RAM, try testing each bank to see if you

> get the problem in one bank or all. One bank is obviously the sick

> RAM chip, ALL banks would be some interface or timing issue, but if

> all banks show the same error then pretty safe to be an interface IC

> issue.

>

> John :-#)#

>

> At 1:39 AM +0100 7/6/05, Martin White wrote:

> >Sorry, but i do get rather confused with this thing from time to time :o)

> >

> >I'm getting a "R/W Error @ F800 BTS 08" when trying to test the ram on one

> > of these MCR boards. Am i right in saying that i need to be tracking down

> > a problem on the data bus, bit 4, bit 3 if you prefer your numbers to be

> > 0 based (1000 = 8, therefore, that's bit 0, 1, 2, then 3 or 1, 2, 3, then

> > 4).

> >

> >And if it were a decode error then that would be the address bus?

> >

> >I'm assuming all is well with chip selects and r/w signals since it's only

> >complaining about bit 08 and not FF?

> >

> >As an aside, i burnt a set of home burnt roms but the 9010 still can't

> > read the things reliably in the MCR sets. It doesn't seem to like

> > anything that's in close relation to the CTC i don't think. It's happy

> > enough troubleshooting the video staging ram and the background ram, just

> > not the program ram or rom :(

> >

> >I'm using a normal Z80 pod with a Z80A processor in it. I'm guessing from

> >reading previous posts that there would be no benefit in trying to blag or

> >borrow a Z80AA since someone else was saying that couldn't cope with MCR

> >hardware either.

> >

> >Martin.

>

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