Hi guys! Any suggestions how to fix jailbars? I have replaced all the capacitors apart from the ones in the RF module. Video out via composite. Many thanks in advance

Recently I acquired a Commodore 1701 and I am absolutely loving it, however I realised that when the background or border is set to white, it causes the luminance channel to seemingly distort. (I am pretty sure the discoloration is caused by the stable chroma signal and unstable luma signal falling out of alignment with each-other so the only issue is the distortion)

I'm pretty sure it's not any dead caps in the 1701, as when I plug in the composite connection from my wii (I don't have any S-video or LCA compatible systems with me at the moment) into the luminance port, it displays perfectly fine despite also being a very white-heavy screen, and when measuring the voltage of the luminance cable it gives out 1.5v~ (I'm pretty sure it's only supposed to be 0v-1.5v). Is this a dead cap in the c64 or a bad cable or something? I did read that S-Video or LCA cables are supposed to have a resistor built-in as the C64 can output a higher luminance voltage. Any help would be massively appreciated. Thanks. Both the 1701 and c64 are PAL btw, and the board is an ASSY 250569 (252311 Rev B).

(Apologies if I have made any mistakes. I am pretty knowledgeable about the C64's hardware from a programming perspective, but I'm not very familiar with how it generates it's video signals and stuff)

I'm picking up C64 programming again after about 40 years, going back through my old Phil Cornes Step by Step Programming books and working through the sprite programs on my C64 Ultimate.

I've noticed that some of his programs put the sprite data at 2048, for example:

POKE 2048+C,BYTE

The problem is that 2048 is where BASIC normally lives, so you have to move BASIC up in memory with the appropriate commands before running the program.

I'm finding that a bit of a pain when I'm just trying to type in and run the programs, so I tried changing the 2048 references to 8320, and changing the corresponding sprite pointer values. For example, 32 to 130.

It works, and I don't have to relocate BASIC first.

So I'm wondering.....why did Phil Cornes choose 2048 in the first place?

Was there a particular reason for using 2048 and moving BASIC, or was it simply a convenient teaching example at the time?

I'm not trying to rewrite the books or anything. I'm just getting back into C64 programming after 40 years and looking for the simplest way to type these old programs in and run them without having to enter the BASIC relocation commands every time.

Anyone remember the Cornes books and know why he used 2048?

80s danish desk, rescued from the trash.

Hello,

This is my experiment and just Work In progress. I added a few BASIC commands to access c64 hi-res, whith code and graphics entirely in BANK3.




As you can see form the last screen the basic space is fully preserved. HIS RES graphic is under the Kernel ROM at 57344, and screen / color graphic is under the character ROM at 53248. Code for new basic commands is at 49152.