What does a fast loader cartridge do ?

[SUCCESS]

Hi people !!!

Still with a defective C64, I've just wondered that if I plug a fast load cartridge (the one I'm using is called "SPARKS") the normal C64 startup message appears and the "F-LOAD" text appears after the "READY"

Without the cartridge, the C64 won't work. It shows the typical blue screen with border, but no message. Only a few "cccccccc" in the firt row. Blind command don't work.

Using the F-LOADER I would be able to run the LOAD command. The test tape (PITFALL from MICRODEAL) seemed to load quite well, but hunged at the end.

Also, at the start up, 2 character are wrong (garbaged).

I'm just wondering how a cartridge works, in order to get some clue to fix my 64.

I checked the three ROMS, SID, VIC, MPU, CIAS and changed all gluee LOGIC !!!!!!.
I checked the chips using another working c64 I had and the work fine.

I didn't check the RAM (it is soldered arrrrrrrrrrrr!!!!) ... just wondering if the F-LOADER skips the RAM test so the 64 starts even with defective RAM.

Anyway .... how it works. I replaces de Kernall .... it uses the Kernall calls ?.

I'm very confused so any expericned user opinion will be very welcomed !!!!!

Many thanks for reading !!!

Pedro.

 

[Raven]

Fastloaders bypass kernel routines to load things more efficiently, but aren't compatible with all drives (mostly unofficial ones) and all software.

Possibly you've got a problem with the built-in routines and using the fastloader is bypassing them?

Someone with more knowledge could theorize more.

 

[carlsson]

Indeed can a cartridge select which startup routines to execute and which to skip. I never considered a fastloader cartridge may choose to skip some Kernel or Basic routines. Generally it sounds odd if your C64 doesn't boot up properly, but if you add the cartridge you get to the Basic prompt and can initiate loading of a program. It really sounds like you have some defective RAM. While I could suggest a test program, it is questionable if you would be able to load/enter it and execute, depending which part of RAM would be bad. Possibly you could find a cartridge that has its own memory test routine and can signal errors instead of hang. There was some diagnostic cartridges back in the 80's which would be used together with a set of harnesses to test all ports.

 

[SUCCESS]

It was a faulty RAM chip.

I think that the troubleshouting guide is not accurate enough. The chips brokes in different way. Some got short, others open, others works in some areas ...
In that case the chip was cold. The useful come from what carlson said ... the fact about the fast load cart ... It just bypass the RAM check. However, the C64 show changed characters (pressing R let _ and pressing * let |). Eventually it got stuck and hang. One bit across the whole memory space was nearly dead. In one time, without the cartridge printed the OUT OF MEMORY error but with the characters scrambled.
I take the first row of ram chips with a desoldering gun, put sockets and them inserted the mems in them again.
With a good 4161 I tested each one (replacing one each time) and finally the C64 come up. No piggybacking.

Thanks for the suggestions !!!

Pedro.

Indeed can a cartridge select which startup routines to execute and which to skip. I never considered a fastloader cartridge may choose to skip some Kernel or Basic routines. Generally it sounds odd if your C64 doesn't boot up properly, but if you add the cartridge you get to the Basic prompt and can initiate loading of a program. It really sounds like you have some defective RAM. While I could suggest a test program, it is questionable if you would be able to load/enter it and execute, depending which part of RAM would be bad. Possibly you could find a cartridge that has its own memory test routine and can signal errors instead of hang. There was some diagnostic cartridges back in the 80's which would be used together with a set of harnesses to test all ports.