CompuServe Thread

Amiga User Forum · Amiga Hardware

#weird problem

5 messages in this thread

#78676From: Jim VentolaNov 21, 1992 1:42 PM

My serial port got flaky and Mac-2-Dos stopped being able to find the mac drive in df1: The dealer replaced the 1488 and the 1489 and two 14 pin sockets. Now the modem works perfectly. Also, an amiga floppy drive at df1: also works perfectly. But Mac-2-Dos still will not find the mac drive. (It does so perfectly on another Amiga). What could have been damaged when the serial port went out that would leave the Amiga drives functioning perfectly but not Mac-2-Dos? What does df1: have in common with the serial port? Thanks.

#78729From: Don Curtis/SYSOPNov 22, 1992 12:37 AM

Jim, Guess what it has in common <grin>…yup, an 8520. Those pesky CIA chips are connected to just about everything and they're usually the first thing to suspect when things get flakey. Don

#78782From: Jim VentolaNov 22, 1992 3:46 PM

Thanks, Don. But the dealer did replace both 8520s while I stood there–still no luck. (Come to think of it, I think he left the newer ones in there.) Does the Amiga drive NOT need the 8520s to work?

#78841From: Don Curtis/SYSOPNov 23, 1992 1:59 AM

Jim, Just about everything has a hook into one of the CIA chips. However, part of the chip can blow, while the rest of it goes on it's merry way. Generally, the CIA chips handle the control lines, while other chips handle the data itself. In the case of the serial port and the floppies…that other chip is PAULA. The 1488 and 1489 chips you had replaced are the serial transmit/receive line drivers. They are connected directly to PAULA and the serial port. 2 other lines of interest connected directly to PAULA are the floppy read and write lines (along with a 3rd, the write enable line). So PAULA is the second place I'd look for a problem. Don

#78863From: Jim VentolaNov 23, 1992 11:20 AM

Thanks, Don. I will mention this to the repair man when I see him. I have the feeling this could be an expensive proposition!