[Techtoolslist] Poss. dumb 9010 query

[John Robertson]

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.