Well I was following the seqeunce given in the manual, which is Address lines, then Data lines, then Ram etc.. I'll run the bus sigs now, and see what I get. Thanks, Kevin 2009/11/25 John Robertson <jrr@flippers.com>
Kevin Moore wrote:
Hi all, in my quest to learn more about using these tools, I've actually come up with a problem, and could use a little explanation.
I'm working on a liberator board, and was using the atari cat box. The first two tests in the liberator manual have you check address lines. Well those checked out good. Next was the Data lines. This is where things fell apart, and I'm not sure what I'm seeing.
Punch in address 0000, and write AA check the D0-D7 lines going to the ls245 well half the incoming lines are the wrong state, and the output of the ls245 is non existent. Ie pins 2-9 have no output.
So I hook up my fluke 9010a thinking there may be something wrong with the catbox, since this is the first time I've used it. Did the same basic setup wddis grounded, and Φ0 Φ2 shorted together. Do a write to 0000 with AA and use my logic probe to check. Same results.
Am I to assume Bad memory at location 0000.??
Yes.
Did you do the BUS Test first? That will show if any address or data lines are misbehaving.
If BUS Test is OK, and you get this problem for RAM @ 0000h, then try the next RAM set - say @ 0800h or 1000h (if RAM present - check Memory Map). If other RAM all checks OK, or ANY RAM checks OK, then the RAM @ 0000h is certainly suspect.
If the RAM is 4-bit, then which bits are locked will tell you which RAM to replace.
John :-#)#
-- John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames) www.flippers.com "Old pinballers never die, they just flip out"
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