Jump to content



Recommended Posts

Hello, a few days ago I took my Commodore C128 out of the closet to play with it.
I turned it on and strange symbols appeared on the screen, so I thought the RAM might have gone bad.
I have changed the RAM that was broken and now it shows a good image and the C64 mode also works very well.
But... in mode 128 the READY command does not appear on the screen.
I have a diagnostic cartridge for my C64, the result is that everything is fine... but of course... it is for C64.
I have a KUNFU FLASH cartridge that runs programs and games in cartridge format (.crt) and floppy disk format (.d64) and everything runs correctly.

I have searched for information about the problem that the READY command does not appear in mode 128 and I have not found where the problem could be.
Link to comment
Share on other sites

First check: Do you have the 40/80 column button pressed? In that case, the C128 boots in 80 column mode using the VDC video output, not the regular video output. If you get a dark grey screen with a green border but no text whatsoever, check if that button is pressed. Release it and restart.

Link to comment
Share on other sites

If you get all the normal text on the start screen except the ready prompt, it could be a problem with the IEC bus. The C128 tries to boot automatically in 128 mode and if something is blocking the IEC bus the computer will hang before the ready prompt appears.

Is there a disk drive connected?

If not, do you have one that you can connect and try to use in 64 mode?

Guess it could be a bad CIA. If the CIA chips are socketed (there are two of them) you can try swapping them and see if the problem changes.

Link to comment
Share on other sites

20 hours ago, carlsson said:

Primera comprobación: ¿Tienes pulsado el botón de la columna 40/80? En ese caso, el C128 arranca en modo de 80 columnas usando la salida de video VDC, no la salida de video normal. Si aparece una pantalla gris oscura con un borde verde pero sin texto alguno, verifique si ese botón está presionado. Suéltalo y reinicia.

Hi. The 40/80 key does not stay tight. If I press it, the screen appears grey inside and green outside.

If I start the computer in C64 mode, READY appears.

11 hours ago, hofster said:

Si aparece todo el texto normal en la pantalla de inicio excepto el mensaje listo, podría ser un problema con el bus IEC. El C128 intenta arrancar automáticamente en modo 128 y si algo bloquea el bus IEC, la computadora se bloqueará antes de que aparezca el mensaje Listo.

¿Hay una unidad de disco conectada?

Si no, ¿tiene uno que pueda conectar e intentar usar en modo 64?

Supongo que podría ser una mala CIA. Si los chips de la CIA están conectados (hay dos), puede intentar intercambiarlos y ver si el problema cambia.


No, I don’t have any disk drives connected.

No, I don’t have a disk drive that I can connect.

Those CIA chips... they’re welded directly to the motherboard?

The computer is mine and has never been modified.



Link to comment
Share on other sites

The CIA chips may be soldered to the motherboard which makes it harder to swap them.

There are diagnostic software that tests the chips and the serial port but it requires external dongles. I think your best shot at finding out if it is your IEC bus that is dead, is to get hold of a floppy drive, SD2IEC, pi1541 or similar and test it in C64 mode.

Link to comment
Share on other sites

25 minutes ago, Onlyfordj said:

The 40/80 key does not stay tight. If I press it, the screen appears grey inside and green outside.

IIRC, the 40 column screen will initialize irrespective of the 40/80 setting, but will only show the BASIC banner in 40-column setting.


On the 80-column (RGBI) 9-pin port on the back of the computer, you can get a monochrome video signal from pin 7.  Use pin 1 or 2 for ground, and connect to a standard monitor.  I did this for years using an Apple green monochrome monitor.

Link to comment
Share on other sites

21 minutes ago, hofster said:

It's correct that it will show an empty 40 column screen if 80 column key is down when started but it's only the ready prompt that is missing if I understand it correctly.

Maybe,  I could not read his post as it looks like it was pasted from another forum and poorly formatted.


@Onlyfordj  Is it the case that you see the BASIC banner?

Link to comment
Share on other sites

I believe the text was copied from some translation service with formatting and all.


It's not clear what the symptom is exactly but missing ready prompt is a known problem and if everything was missing from the screen, I think it would be strange to say that the ready prompt was missing instead of saying that the screen was blank or empty but it may all be in the translation.

Link to comment
Share on other sites

49 minutes ago, hofster said:

I think it would be strange to say that the ready prompt was missing instead of saying that the screen was blank or empty but it may all be in the translation.



I have seen two drives with conflicting device number 8 on the serial buss preventing the READY prompt, too.  Otherwise, this is not a problem I have ever had to troubleshoot.

Link to comment
Share on other sites

Are you getting a screen like this?




If so, then try to PRESS then RELEASE these buttons in this order:

  1. ESC
  2. X



If you now see a blinking cursor in the top-left corner then your 128 is starting up on the 80 column display.  You can start using your 128 in 40 column mode at this point.




That interference pattern (not the moiré pattern) to the right and below the red arrow is the signal bleeding over from my 80 column connection to my C= 1084 monitor. I need to reroute the cables or something to clear that up.


  • Like 1
Link to comment
Share on other sites

37 minutes ago, Onlyfordj said:

Hola. Sí, soy de España. Mi idioma inglés es muy pobre y uso una aplicación de traducción.


Iniciar en modo 128 y iniciar en modo 64

Holy cow... my college Spanish teacher was right... I actually understand this! :D


Okay, so BASIC banner but no READY.


When hung up like this, try RUN/STOP-RESTORE.  See if that brings up the READY prompt.  ISTR there is a key to hold at power-up which bypasses boot... anybody know or remember?

  • Haha 1
Link to comment
Share on other sites

2 hours ago, Onlyfordj said:


The picture shows that at least one of your CIA chips is socketed and doesn't need soldering. The other one is most likely also in a socket.

Try swapping them and see what happens to the ready prompt.



Pay attention to the chip directions and notches on the sockets If you swap them!

One of them is rotated 180 degrees in relation to all other chips on the board.

Edited by hofster
Link to comment
Share on other sites

22 hours ago, SpiceWare said:

Estás consiguiendo una pantalla como esta?




Si es así, entonces trate de PRESS, entonces RELEASE estos botones en este orden:

  1. El CES
  2. X



Si ahora ves un cursor parpadeante en la esquina superior izquierda, entonces tu 128 se inicia en la pantalla de la columna de 80. Puede comenzar a usar su modo de columna 128 en 40 en este punto.




Ese patrón de interferencia (no el patrón de moiré) a la derecha y debajo de la flecha roja es el sangrado de señal de mi conexión de 80 columnas a mi monitor C= 1084. Necesito desviar los cables o algo para aclarar eso.


No cursor appears on the screen after starting in 40/80 columns and pressing the keys you tell me. Keep in mind that I connect the computer through RCA and maybe the process you tell me is for if I use monitor. Thank you.

20 hours ago, carlsson said:

Parece que si pulsas RUN/STOP durante la bota, te lanza al monitor de lenguaje de la máquina. Desde allí se puede escribir X y volver para llegar a BASIC sin intentar arrancar un disquete.

This is what appears when I press the RUN/STOP key and turn on the computer. While on this screen the keyboard does not respond.


20 hours ago, hofster said:

La imagen muestra que al menos uno de tus chips de la CIA está enchufado y no necesita soldadura. El otro es muy probable que también esté en un enchufado.

Intenta intercambiarlos y ver qué pasa con el prompt listo.



Presta atención a las direcciones de chip y muescas en los enchufados Si los intercambias.

Uno de ellos se gira 180 grados en relación con todas las demás fichas en el tablero.

Exchanged chips (they are in sockets) fixing me in the correct insertion position. Still not showing the READY command. Does not show READY command.


Many thanks to all!!!


Link to comment
Share on other sites

Hm, so the computer boots into the machine language monitor, displays the registers but just like in BASIC, it does not provide a prompt. If the CIAs were that bad, you wouldn't have the C64 mode working as well. Does the C128 have an error prone PLA just like the older C64 models? Still, wouldn't that show up in C64 mode as well? Rather curious case.


Ray Carlsen has a document on the C128 as well, but the only mention of the cursor is the CIA which seems unlikely IMHO.



Edit: This seems like a far fetched cause, since you're not getting a blank screen, but a screen without the prompt:


U35 318020-03 C128 Kernal ROM

Comes up in C64 mode, but cartridge doesn't work. Partial failure: blank screen in 128 mode only.

Edited by carlsson
Link to comment
Share on other sites

Hi. I was given a Commodore C128 this morning that works properly. I have removed the CIA and put in my computer the correct CIA of the other computer... and the prompt READY does not appear.


On the computer they have left me, with my CIA if the prompt READY appears.

Edited by Onlyfordj
Link to comment
Share on other sites

So it's not the CIA.

Maybe it's not related to the IEC bus at all.

Check what happens if you start it in C64 mode and issue the command LOAD"*",8

It should normally return a device not ready error or something like that.

If there IEC bus is causing the problem, I guess it will hang.

Link to comment
Share on other sites

49 minutes ago, hofster said:

Entonces no es la CIA.

Quizás no esté relacionado en absoluto con el bus IEC.

Compruebe qué sucede si lo inicia en modo C64 y emite el comando LOAD"*",8

Normalmente debería devolver un error de dispositivo no listo o algo así.

Si el bus IEC está causando el problema, supongo que se bloqueará.

Thank you very much for your help. This is what appears.



Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...