gpatrick@handel.mpr.ca (Greg Patrick) (09/28/90)
Does anyone know much about the serial port on the Amiga 500? I have the following (damn annoying!) problem: I have a Smart One 2400 baud modem that works just dandy with my former roomie's PC clone. If I plug the modem into the wall and turn it on, without connecting it to my Amiga, everything is fine - only the MR (modem ready) light comes on. However, if I connect the modem to my Amiga and turn them both on, then the modem has the MR, the SD (send data), and the TR (terminal ready - I don't really know what this one signifies) lights all come on. I've tried 2 cables, one brand new, so I doubt it's that. I know the modem works with a PC so it's not the modem. I think either I have shorted pins on my Amiga serial port or that one or both of my 8520 chips are bad. My Amiga manual lists the pinouts for the serial port but doesn't give the active voltage levels, nor does it tell what voltage each pin should be if the port is not being used. What do you think it is? Also, is an 8520 chip a standard chip that I can pick up at an electronics shop, or is it a Commodore chip that I can't easily get? Please reply to: gpatrick@mprgate.ca or (if that bounces) gpatric@handel.mpr.ca P.S. I'm desperate! I need to log on to work from home! P.P.S. I'm kind of a novice Amiga guy, so try to be detailed. Greg.
billsey@agora.uucp (Bill Seymour) (09/30/90)
In article <2358@kiwi.mpr.ca> gpatrick@handel.mpr.ca (Greg Patrick) writes:
:Does anyone know much about the serial port on the Amiga 500?
:
:I have the following (damn annoying!) problem:
:
:I have a Smart One 2400 baud modem that works just dandy with my former
:roomie's PC clone. If I plug the modem into the wall and turn it on,
:without connecting it to my Amiga, everything is fine - only the MR
:(modem ready) light comes on.
:
:However, if I connect the modem to my Amiga and turn them both on, then
:the modem has the MR, the SD (send data), and the TR (terminal ready - I
:don't really know what this one signifies) lights all come on. I've
:tried 2 cables, one brand new, so I doubt it's that. I know the modem
:works with a PC so it's not the modem.
:
:I think either I have shorted pins on my Amiga serial port or that one
:or both of my 8520 chips are bad. My Amiga manual lists the pinouts for
:the serial port but doesn't give the active voltage levels, nor does it
:tell what voltage each pin should be if the port is not being used.
:
:What do you think it is?
Sounds like the 1488 that is associated with that port is bad.
That's not too unusual, since that's what gets zapped if you hot plug
in something with the connector shifted slightly. Just take it in to
a repair place and have that chip replaced. (A 1488 chip is real cheap,
Typically less than $.20 in quantity and less than $1.00 in onsies.
Expect to pay for a hour or so of labor though, replacing it means
pulling the motherboard all the way out and desoldering.)
:Also, is an 8520 chip a standard chip that I can pick up at an
:electronics shop, or is it a Commodore chip that I can't easily get?
Depends on your local electronics shop. the 8520 is a
slightly modified version of the 6526 and they are both Commodore
chips. But they're also useful in other applications.
:Please reply to: gpatrick@mprgate.ca or (if that bounces)
:gpatric@handel.mpr.ca
:
:P.S. I'm desperate! I need to log on to work from home!
:P.P.S. I'm kind of a novice Amiga guy, so try to be detailed.
:
:Greg.
--
-Bill Seymour ...tektronix!reed!percival!agora!billsey
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