That's no time at all in this space.

My initial reason for making it is I needed a way to compare operating systems on different disk images. So i was looking for a "nearly instant" checksum on 256 byte blocks. I did actually consider CRC32, but for one a 32 bit checksum on 256 bytes seems like ...

I finally built a replacement of the Dongle card but used a C64 to test it:

The variants: Original, CPLD version, possible remake with DIL-replacement: Test sequence output after reset: Test hardware: Case closed. Finally

@BB8: What assembler did you use to translate your file?

It's actually the checksum of the BASIC rom.

I'm away until Saturday but I'll try to realize @Jeff proposal.
Nice challenge

@BB8:

I took your idea and did it on C code...

uint32_t calcCRC32_Nib(uint8_t crcReg[8], const uint8_t* buffer, uint32_t size)
{
static const uint32_t crcTable7[] = {0x0, 0x1, 0x3, 0x2, 0x7, 0x6, 0x4, 0x5, 0xE, 0xF, 0xD, 0xC, 0x9, 0x8, 0xA, 0xB};
static const uint32_t crcTable6[] = {0x0, 0xD ...

Although no one really needs it... a replacement is here:

Was this how the above explanation was meant, or is this unexpected? If the latter, could this work out differently on different CIA models perhaps?

Maybe we will take a look at that as soon as the 6526 has been vectorized and dissected. But this may take some time... if not years until this ...

Hi @ll,

maybe this one is interesting for some of you:

MOS internal Documentation about 6522 problems and possible corrections (that were never made).
Please excuse the slightly too small scan. I don't have a Scanner for this paper format (yet).

/Frank

That's all for now.
Now to take a break, because that Paula dissection was pretty intense.
Rockwell R6545 is next

While 'ttlworks' takes his much deserved break I'll proceed vectorizing the R6545.

In order to give a short glimpse about the current state:

R6545.jpg

I've been drawing every ...

The microscopic pictures of the 6572R1 are ready...

https://cdn.knightlab.com/libs/juxtapos ... 95d9b17862

Some time ago someone pointed out that (contrary to my belief that there's only one revision of the VIA / 6522 (i.e. Rev. 0))
MOS also produced a 2nd version "R1" for a short period of time (around 1988) but resumed using the Rev. 0 layout:

VIAs.jpg

One can distinguish the revision by looking at ...

Please note that the photograph of the Rev.A contains some errors/tearing.

Thanks - that's an interesting video from TubeTime, and is thoughtful and analytical despite the title.

The conclusion is that the circuitry needed to implement ROR is missing from the first revisions of the chip: that's not a bug, it's a decision. And there was evidently then a reversal of the ...

All very good work, well done!

If you have to guess which are NMOS and which PMOS transistors, you'll usually find the PMOS are larger/stronger with a wider channel (which is to say, longer poly gate).

Yes. These are the two criteria I use to distinguish them:

1. Size/Width
2. Connection to GND ...