A Grand Day Out

[stephen_usher]

This is definitely keeping you out of mischief.

[rubber_jonnie]

This is definitely keeping you out of mischief.

It certainly is

[rubber_jonnie]

OK, so I think I have the C128 ROMs sorted out now.

I need 3 images, Basic Lo, Basic Hi and the kernal as follows:

Basic
318018-02 Lo
318019-02 Hi

Kernal
318020-03

And apparently 27C256's are suitable as long as you double up the ROMs to fill the space.

I'll download the images from Zimmers later on.

[stephen_usher]

[rubber_jonnie]

@PhilC

Good news this morning.

Before work I replaced the BASIC HI ROM (U34) and no change. I then replaced the BASIC LO ROM (U33) and we seem to be in business!!!

I don't get crashes anymore as soon as I boot, and the GO64 behaviour is as it should be

IMG20240220090057.jpg (281.52 KiB) Viewed 2032 times

Hitting 'Y' and enter takes me here:

IMG20240220090106.jpg (182.46 KiB) Viewed 2032 times

And I can type and run simple basic programs too:

IMG20240220091254.jpg (311.61 KiB) Viewed 2032 times

Something that was impossible before due to the instant crash into monitor mode.

Oddly the diag cart ran perfectly the first time after changing the ROM, but since then it still fails with RAM and PLA errors. I'm inclined to think that the problem is more one of the diags and not the machine, because I refuse to believe every last RAM IC is bad.

I'll keep looking at that, but I know Adrian Black had a similar issue with a C64 and getting the correct diag software.

Nice to see the MOS ROMs living up to their usual reliability standards... Interestingly Noel from Noels Retro Lab recently had a similar BASIC ROM failure, MOS IC again, but on a C64.

Also nice to see that you can use 27C256 ROMs as a direct swap as long as you double up the ROM file in each as the original ROMs are 16KB. I've attached the 27C256 ROM files here, just take off the .txt extension and unzip, then burn whichever image you need to a 27C256.

I have also just replaced the Kernal ROM, as it's also a MOS part...

Also now considering burning the later ROMs as well and swapping them out, and I still plan to replace all the single wipe sockets too.

Happy days

[PhilC]

That’s cool that you got it all sorted Jon.

I replaced the four roms in line with 27C128s and it’s been fine. I’ve got the old roms which do work but are being kept for testing only.

[rubber_jonnie]

That’s cool that you got it all sorted Jon.

I replaced the four roms in line with 27C128s and it’s been fine. I’ve got the old roms which do work but are being kept for testing only.

Yeah, I think the old ROMs are definitely suspect. I have a stockpile of 256's, but no 128's, so it was the simplest way to go. I'll probably also replace the C64 ROM as well, it's another MOS part and they have never had a good reputation for reliability.

[stephen_usher]

Excellent news!!!!

[rubber_jonnie]

Excellent news!!!!

Made my day

And just to add, my SD2IEC works fine for the C128 and C64 parts of the machine

This is on the C128 mode:

IMG20240220111253.jpg (280.54 KiB) Viewed 2020 times

This is C64 Mode:

IMG20240220105806.jpg (277.28 KiB) Viewed 2020 times

And this loaded and runs just fine under C64 mode too, plus it worked great with my Epyx Fastload cart in C64 mode:

IMG20240220110835.jpg (303.56 KiB) Viewed 2020 times

So things are looking good. I've also downloaded the latest C128 BASIC ROMs and Kernal ready to replace and see if things change much.

Need to download some of the disk images that @PhilC pointed me at.

[rubber_jonnie]

@PhilC

There you go, I said I'd do it. CPM on the 128:

IMG20240220141209.jpg (258.66 KiB) Viewed 2014 times

They weren't thinking too hard about colour schemes that's for sure!!

Need to look at 80 column mode as well I think.