Topic: 1571CR defective DOS-chip?

[MIRKOSOFT]

Hi!


My 1571CR in my C128DCR was working correctly... today afternoon I turned on my computer and tried to access...


I tried standard DOS commands (DLOAD,DSAVE, BLOAD,BSAVE).. result: ?FILE NOT FOUND
I tried to show directory, looks like there's not diskette and LED blinks.


Then I used JiffyDOS commands, also @UI - and reports: 31,SYNTAX ERROR....


So, I tried to use my BIOS program and there was recognized as: DISK DRIVE: DOS UNKNOWN, normally was recognized as C1571CR: CBM DOS 3.1...


Is DOS-chip defective? 'Cause I think that mechanism can't to be damaged - computer was not moving, replacing etc...


If is DOS-chip defective, which chip needs to replace? (on-board label?)


Many thanks for every help, reply or comments.


Miro

[Hydrophilic]

That's really bad if you get SYNTAX ERROR from UI command.
 
It could be something simple like disk drive is not receiving command correctly.  Unplug all other serial devices and try again.
 
If that doesn't work, you should pay close attention to the activity light when you power on.  DOS will check RAM and ROM and flash an error code if these fail the test... I've never seen it so I don't know exactly what it looks like... but it should look different than normal 'no disk error' flashing.
 
You can also perform the test after drive is powered on by sending command "U0>T" and it should report 00, OK, 00, 00.
 
If these tests are okay (and because the drive does send response like SYNTAX ERROR) then probably the CPU and memory are OK.  The two main IO chips are the VIAs (6522) and there is also CIA (6525?).  Well, this is for real 1571... I'm not sure about CR version...
 
Because you have JiffyDOS, then I would guess the chip with a sticker on it is the ROM... my JiffyDOS has a sticker as well... the only chip that has a sticker...
 
I don't know if any of that is helpful... but good luck!
 

[MIRKOSOFT]

Hi Robert!


Thank you for explaining... I was searching in my memory... and I forgot that computer cannot to have connected too many devices...


Of course, I unplugged all serial devices and works!


Devices limit is only about 1571CR! 'Cause if I turn on 64HDD, I have there +3 devices and every works correctly...


I mean that it's about serial bus. I forgot that I connected CMD HD with serial cable... so, only one solution is here:


RAMLink Parallel Cable! My friend sold it to me with 16MB REU, but not arrived yet... I'll report if it will have effect...


Thank you!


Miro