6. When something goes wrong
The line above the screen
The toolbar's right-hand end says how the machine is doing, once a second:
| It says | What it means, and what to do |
|---|---|
| Switching on… | The page is loading the machine and its ROMs. It takes a moment the first time. |
| Running · 100% of a real C64 | All is well: the machine is running at a real C64's speed. |
| Running · under 100% | This computer cannot keep up, so everything runs slower than a real C64, sound included. Close other tabs or programs; a phone or an old laptop may not manage the full speed. |
| Paused | You pressed Pause. Press Go on. |
| The ROMs did not load | The page could not fetch the machine's ROMs. Load the page again; if it keeps saying it, tell us (below). |
Under the toolbar, one line answers whatever you last did (put a disk in, pressed PLAY, pressed Freeze). When something could not be done, that line turns red and says why: a file that is not a disk, tape or cartridge; a broken disk image; PLAY with no tape in. Whatever was in before stays in.
The C64's own messages
These are the C64's, word for word as a real one prints them:
| On the screen | What it means |
|---|---|
?SYNTAX ERROR | BASIC did not understand the line. Check the spelling, and the quotes around a name. |
?FILE NOT FOUND ERROR | No file by that name on the disk or the tape. LOAD"$",8 then LIST shows the disk's files; a name must match exactly, or end in * to match its start. |
?DEVICE NOT PRESENT ERROR | Nothing answered on that device number. Drive 8 switches on the first time a disk goes in: put a disk in under Disk (or drop a .d64 on the screen) first. |
?OUT OF MEMORY ERROR | The program is too big for BASIC's memory, or the stack is full. |
PRESS PLAY ON TAPE | The C64 is waiting for the tape: put one in under Tape, then press PLAY there. |
The drive's messages
The 1541 keeps its own message, which BASIC does not print. To read it, type:
OPEN15,8,15:INPUT#15,A,B$,C,D:PRINTA;B$:CLOSE15| Number and text | What it means |
|---|---|
| 00, OK | All is well. |
| 26, WRITE PROTECT ON | The disk's notch is covered: open it under Disk. |
| 62, FILE NOT FOUND | No file by that name on this disk. |
| 63, FILE EXISTS | A file by that name is already there: SAVE with @0: in front of the name to replace it. |
| 72, DISK FULL | No room left on the disk. |
| 74, DRIVE NOT READY | No disk in the drive. |
| 20 to 25, READ ERROR or WRITE ERROR | A damaged part of the disk. Some copy-protected disks have these on purpose: keep them as .g64, which keeps the disk's surface exactly. |
| 73, NEXUSROM+ DOS V2.6 1541 | The drive has just switched on. Not an error. |
A program that stops
A program that waits for a key or the joystick looks stopped but is not: try Space, RETURN or fire. RUN/STOP (Esc) stops a BASIC program; RUN/STOP and RESTORE together (Esc and Page Up) bring most programs back to READY. A few programs switch RESTORE off on purpose, as a real C64 lets them (by leaving CIA 2's interrupt waiting); then only Power stops them. Some programs jam the processor on purpose, as copy protection or by a fault: a real C64 then answers nothing, and nor does this one. Press Power to start again. With Chips on, the processor's panel shows where it stopped.
No sound
- Browsers keep a page silent until you click it or press a key on it: click the screen once.
- The button should say Sound on; if it says Sound off, press it.
- More → Sound check plays a few notes through the SID. If you hear them, the sound works, and the program is simply silent.
- A program written for the other SID may sound wrong: More switches between the 6581 (the first C64s) and the 8580 (the C64C).
A game that does not answer the joystick
- Most games read the joystick in port 2, some in port 1. More → Joystick switches which port the keys and your game controller are plugged into; try the other one.
- The number pad is the joystick (8 2 4 6 to move, 7 9 1 3 for the diagonals, 0 or 5 to fire). On a keyboard without one, More → Arrows makes the arrow keys and Space the joystick.
- A game controller wakes up when you press one of its buttons.
- Click the screen first: the machine only hears the keyboard while the screen has it.
Telling us
If a program will not run, or the machine does something a real C64 would not, use Help → Report a program that will not run. Tell us which program (its name, and where it came from), which machine, what you did and what happened: the exact words on the screen, and what the line above the screen said. Every report is a test we can add, so the same fault never comes back.