LARRY's COMMODORE 8-BIT
PROBLEM TROUBLESHOOTING LIST
------Updated 02/14/1999----
BY LARRY ANDERSSON,
COMMODORE COLLECTOR AND ENTHUSIAST
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This is a simple checklist FAQ of some of the easily correctible but not always
well known problems you may experience with your Commodore 8-bit computer.
NOTE: This FAQ is by no means complete, much of the information covered here
deals with Commodore 8-Bits that I have had experience with and
reference materials on. If you have stuff to add or revisions to current
information please e-mail me at:
larry@portcommodore.com
TOPICS:
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* MY COMPUTER POWERS UP STRANGELY
* IT DOES NOT PRINT ON THE SCREEN WHAT I TYPE
* I CANNOT LOAD ANYTHING BUT EVERYTHING SEEMS TO BE WORKING OK.
* I AM HAVING TROUBLE FORMATTING DISKS OR SAVING PROGRAMS
* I RUN A GAME OM MY 64 AND I CAN'T SEE ALL OF IT
* MY COMMODORE 64 CP/M CARTRIDGE DOESN'T WORK
MY COMPUTER POWERS UP STRANGELY
+ (64) If the screen is full of multi-colored garbage text, it is most likely
that your power supply died.
+ PET If you get a Blank Screen you might have your IEEE-488 connector in the
user port by mistake or your user port device cable upside-down.
+ Some'flat' 128's power switches can't fully engage because of the case
design, if you get 'flickering' try filing the hole around the switch.
+ PETs are prone to have the chips come unseated from their sockets. With
the computer OFF, Push down (not too hard) on the top of each socketed
chip, turn back on the power and see if it made a difference.
IT DOES NOT PRINT ON THE SCREEN WHAT I TYPE
+ Make sure the 'shift-lock' key is not locked down
+ Check the joysticks that are plugged in, if one is pushed to the side or
the fire button is jammed down, this will cause keyboard problems.
+ Check the keyboard for stuck-down keys (this happens from time to time,
especially on SX 64s.
+ On older machines the keyboards may become dirty were some keys cease
working. (This text presently does not have a keyboard cleaning procedure,
but I will write one in the future.
I CANNOT LOAD ANYTHING FROM DISK OR TAPE BUT EVERYTHING SEEMS TO BE WORKING OK.
+ TVs and Monitors put out alot of interference especially on the left side
of the screen, Datasette Drives or Disk Drives may not communicate well if
they are too close to the display or on the left side, try re-arranging
your drives.
+ Some commercial programs leave the floppy drive's read/write head on a
half-track and make the drive unable to read disks. Try sending an
Initialize Drive command (OPEN 15,8,15,"I":CLOSE 15) without a disk in
the drive to reset the heads, then try loading again.
+ If it is a drive you just got it may not be set for device 8, try loading
the directory using device 9, 10 or 11. (i.e. LOAD"$",9)
+ The 8050, 8250, and SFD-1001 cannot read disks created with the 1541, 1571,
4040 or 2031. Make sure you are using a comaptible disk formats.
+ On the PET tape, make sure sound is turned off: POKE 59464,0:POKE 59466,0:
POKE 59467,0 The sound generator interferes with the tape operation.
+ Add a 0: (or 1: for second drive) before the file name of disk programs,
this will make the disk attempt an Initialize before loading the file.
+ If you are trying a LOAD"*",8 try doing a LOAD"?*",8 It sometimes does
the trick. Also see previous hint.
+ If you are using a fast-loader cartridge or ROM, it may not be comaptible
with the drive or program you are trying to use.
I AM HAVING TROUBLE FORMATTING DISKS OR SAVING PROGRAMS
+ (Tape) make sure the 'write protect tab' isn't punched out, if it is, you
will need to cover the write protect hole with tape.
+ On the PET tape make sure sound is turned off: POKE 59464,0:POKE 59466,0:
POKE 59467,0 The sound generator interferes with the tape operation.
+ The Commdore 2040,4040,2031,8050,8250,SFD-1001,1540,1541,1570,1571,
and 1581 cannot reliably use high-density disks. Use Single or Double
Denity Disks on the 2040,4040,2031,1540,1541,1570,1571, and 1581. The
8050, 8250 and SFD-1001 use 96 track per inch Disks. Use them if you
can find them, though you might squeak by with Double Density disks.
+ If it is a previously used disk that is giving you heck, make sure to add
the 2-character disk id (i.e. "N0:NAME,ID") to do a complete disk format
and not a simple directory erase.
+ Add a 0: (or 1: for second drive) before the file name of disk programs,
this will make the disk attempt an Initialize before saving the file.
+ Are you using a unique file name? the Disk Drive will not automatically
overwrite old files. Issue a 'scratch file' command before saving.
+ Beware of old commercial software disks, some nasty (and stupid) vendors
punched holes (which can mess up the drives heads) in the recording area.
+ 1581 diskettes are VERY prone to failure (called the click of death, as
the disk starts making a clicking sound when unreadable), handle with care.
I RUN A GAME OM MY 64 AND I CAN'T SEE ALL OF IT
+ Over the years Commodore changed the Commodore 64's method of how it
assigned color to the characters on the screen (which are blank) when it
cleares it. Some programmers assumed cleared screens will contain white
characters or the last used character color, which is not always the case.
Fortunately there are not too many programs with this problem.
MY COMMODORE 64 CP/M CARTRIDGE DOESN'T WORK
* Commodore's CP/M cartridge for the 64 relies on precise timing of the 64
when Commodore did revisions to later 64s that timing was altered. Only
early model 64s have the compatible timing to support the CP/M cartridge.
A good sign you have an early 64 is if the video connector has ony 5
pins instead of the 8 in the later 64s.
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