My C64 and 1541 aren't talking to each other!?!

[DistantStar001]

One of my c64's just stopped communicating with its serial port. One moment it was fine, as I was just trying to get it to change the drive number on a 1541, and the next, I tried retrieving a directory, and then nothing. It just sits there "searching for $". No curser. Just searching. As for the drive. There is no response. The red LED won't even light up. However, the drive does reset when I power-cycle the computer. 

 

I've tried two drives and a Pi1541 with much the same result. I tried three different serial cables as well (two I had made myself, but the third was original to one of the drives). I then tried both drives on two separate c64's. Admittedly, the first gave me a "Device not present error", but I reflowed the solder on the serial port and now both drives respond as expected. The second had no problems with either drive. The drives also responded as expected to a VIC-20 as well. 

So I'm reasonably sure the issue is the computer. I did open it up. Didn't want to, since it was sealed over the center screw with a warranty sticker and I wanted to keep it pristine. But as it turned out, there was no point as it was from a repair shop and whoever was in there had replaced the PLA and SID as at some point and failed to clean up their flux. I cleaned that and reflowed the solder on the serial port (didn't think that would help, but worth a try). Sadly no luck. At least I got rid of that stupid cardboard RF shield. 

 

The computer seems to boot normally. There is a curser on the screen. No graphical corruptions and the keyboard is fully functional. As far as I can tell, the joystick ports work. (hard to test fully as I don't have a harness for diagnostics, and I can't load any software that would make use of a paddle or mouse). 

I think it might be one of the CIA's, but want to explore all possibilities before I 
I take a soldering iron to it. Also, if someone could tell me which CIA I should focus on, that would be appreciated.  Very Happy 

Side Question: I've tried changing the Drive number a number of times with no luck. I'm typing the command directly from the original VIC-1541 Single Floppy Drive User Manual with no luck. Every time the drive still thinks it's device 8. 

 

The commands I've been using are: 

 

OPEN 15,8,15 

 

PRINT# 15, "M-W:" CHR$(119)CHR$(0)CHR$(2)CHR$(10+32)CHR(10+64) 
Tried this with and without spaces 

 

CLOSE 15 
I don't always do this line 

 

I'm trying for device 10, since my Pi1541 is set to 9, and I want to see if I can get all three to work together. Also, I don't want to permanently alter my drives as I have several c64's and VIC-20's so the drives do get swapped between them. In any case, What am I doing wrong?

[carlsson]

CIA #2 at $DD00 handles the serial bus and user port. Now you just need to look at the schematics to figure out which CIA is #1 and #2.

 

http://www.zimmers.net/anonftp/pub/cbm/maps/C64.MemoryMap

http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/index.html

 

As for your method to change the drive number, that is exactly as the manual suggests. For some reason the manual omits the colon between the command and the parameters, so you might as well try that in case it isn't supposed to be there. The first two values are low and high bytes to the memory address, so in case the drive swallows the ASCII comma as part of the address, you would be mucking at $773a instead of $0077.

[Frozone212]

Lovers spats happen, maybe she's just pissed she's doing all the work for no payoff lol

[+OLD CS1]

4 hours ago, Frozone212 said:

Lovers spats happen, maybe she's just pissed she's doing all the work for no payoff lol

Definite communications screw-up: she executes TALK while I execute UNLISTEN.

[zylon]

17 hours ago, Frozone212 said:

Lovers spats happen, maybe she's just pissed she's doing all the work for no payoff lol

someone's formatting on the couch tonight...lol

[Frozone212]

1541 Drive: "I know i'm kinda slow in some departments but i still love you!"

C64: You may love me but your attention is elsewhere during lovemaking

1541: "You expect me to listen to clients and you?"

C64: "That does it, i'm getting a divorce"

(cue 1571)

C64: "Harder, Your drive is so much bigger than my Husbands"

[zylon]

3 hours ago, Frozone212 said:

1541 Drive: "I know i'm kinda slow in some departments but i still love you!"

C64: You may love me but your attention is elsewhere during lovemaking

1541: "You expect me to listen to clients and you?"

C64: "That does it, i'm getting a divorce"

(cue 1571)

C64: "Harder, Your drive is so much bigger than my Husbands"

classic example of not enough disk ?

[Frozone212]

On 5/1/2021 at 8:06 PM, zylon said:

classic example of not enough disk ?

that made me laugh

[DistantStar001]

On 4/27/2021 at 12:13 AM, carlsson said:

CIA #2 at $DD00 handles the serial bus and user port. Now you just need to look at the schematics to figure out which CIA is #1 and #2.

 

http://www.zimmers.net/anonftp/pub/cbm/maps/C64.MemoryMap

http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/index.html

 

As for your method to change the drive number, that is exactly as the manual suggests. For some reason the manual omits the colon between the command and the parameters, so you might as well try that in case it isn't supposed to be there. The first two values are low and high bytes to the memory address, so in case the drive swallows the ASCII comma as part of the address, you would be mucking at $773a instead of $0077.

Thanks for this, I did manage to narrow it down to U2.  Just replaced it today and now my C64 and 1541 are back on speaking terms!

 

On 4/30/2021 at 6:32 PM, Frozone212 said:

Lovers spats happen, maybe she's just pissed she's doing all the work for no payoff lol

 

On 5/1/2021 at 11:48 AM, zylon said:

omeone's formatting on the couch tonight...lol

 

On 5/1/2021 at 4:08 PM, Frozone212 said:

1541 Drive: "I know i'm kinda slow in some departments but i still love you!"

C64: You may love me but your attention is elsewhere during lovemaking

1541: "You expect me to listen to clients and you?"

C64: "That does it, i'm getting a divorce"

(cue 1571)

C64: "Harder, Your drive is so much bigger than my Husbands"

 

On 5/1/2021 at 8:06 PM, zylon said:

classic example of not enough disk ?

I had no idea no idea old computers had such complicated love lives!  Although in my case there's a happy ending!  

[+OLD CS1]

20 hours ago, DistantStar001 said:

Although in my case there's a happy ending!  

[Frozone212]

6 hours ago, OLD CS1 said:

to which i have this to say:Quagmire as RoadRunner "Giggity giggity" - YouTube