collins@well.sf.ca.us (Steve Collins) (08/10/90)
Ack Pfft!
I have been working on my Frances board to the detriment of my
marrige and sanity for several months now. Still no joy.
I finally figured out that I had some wierd data buffers and saw some
light at the end of the tunnel when I put LS chips in.
Now, the darned thing sort of works on rare occasions with 2 drams installed.
There are a couple of oddities still to be explained however:
1) most of the time I just get zeros out of the ram. It seems to be refreshed,
the data buffers are being switched and I'll be darned if I can find anything
amis, but the numbers I put in, don't come back out. The thing works about 1
time in 10 or 20 ( ie just enough to keep me from pitching it out the window),
but when it does, it seems to work till powerdown, without being flaky.
I get real jazzed and switch it off to put in more ram and it doesn't work
when I turn it on again.
2) When I put 2 chips in, the memory (whether it works or not ) seems to
show up at unexpected addresses. For example: If I put the chips in the
back two sockets ( as you look at the amy from the front) the ram
seems to show up at 0x400003, 0x400007... etc rather than at 0x400000,
0x400004... Aren't these chips connected to data 0-8? Is this right? If not
then what's happening??
3) Occasionally, the thing hangs at modeload with francyc low.
Other info:
I have the thing in an A500.
My Lucas went together in a snap and worked fine.
I can solder, and haven't ripped traces off the board or anything like that.
I have run the clock through a buffer because it seemed to help me
get lucas through the boot sequence and modeload with the frances in place.
I wasn't sure what to do with the termination resistors (?) on the clock ,
but I left them on the clock (ie before the buffer rather than after...)
Any, hints, wild guesses, or even just stuff I can check out would be
highly appreciated.
TIA
steve collinsvincelee@tornado.Berkeley.EDU (Vincent H. Lee) (08/12/90)
In article <19482@well.sf.ca.us> collins@well.sf.ca.us (Steve Collins) writes: > >Ack Pfft! >I have been working on my Frances board to the detriment of my >marrige and sanity for several months now. Still no joy. > >3) Occasionally, the thing hangs at modeload with francyc low. ^ I had this problem. I never found out why the controller sometimes rejected programming. Solution? add a loop in ATM so it does the programming (read statement) about 1000 times or so. (ok, it sounds stupid, but it worked for me) > >Other info: >I have the thing in an A500. I got completely unpredictable and generally WEIRD behavior from my Frances board when I moved it to my 500 until I added a grounded EMI shield beneath the controller chip and nearby circuitry. I just used a scrap piece of copper-clad board taped under frances, and adding a bunch of little wires soldered between the board and various ground points on frances. > steve collins
sjf@borage.cs.reading.ac.uk (Steve Fisher) (08/14/90)
In article <19482@well.sf.ca.us> collins@well.sf.ca.us (Steve Collins) writes: >I have the thing in an A500. >My Lucas went together in a snap and worked fine. >I can solder, and haven't ripped traces off the board or anything like that. Ah a lucas board for the A500 where can I get one ? I would like to build a lucas/frances for my A500 but I thougth that the lucas board was to fit into an A1000. If someone could let me know where to get a lucas board etc for A500 it would be much appreciated. _ _ |_ |_ Steve (Scredgie) Fisher _|| Reading University, Computer Science Dept, Micro Lab.
dash@legs.UUCP (Darrell Shively) (08/16/90)
in article <2741@onion.reading.ac.uk>, sjf@borage.cs.reading.ac.uk (Steve Fisher) says: > Ah a lucas board for the A500 where can I get one ? > I would like to build a lucas/frances for my A500 but I thougth that the > lucas board was to fit into an A1000. Right. LUCAS and FRANCES were designed to fit in an A1000. You *can* physically plug them into an A500, and they *should* work. Of course, the case won't close. But who cares about that ? :-) :-) -- Darrell M. Shively II | internet: dash@ast.com | Voice: (714) 727-8637 AST Research Inc. | uucp: ..uunet!legs!dash | Fax: (714) 727-9358 -----------------------+-----------------------------+----------------------- "These are my opinions. No one else shares them." |