Denial

Even at this resolution, I can tell that the 4 sine/cosine generators for the chrominance are a different layout, and also the logic to the side of this, including the Phase Alternating logic and sub-carrier drivers. They're a different layout as well. The layout for the resistors that control the m...

Jogi wrote:DIE Shot 6561-101

Do you have access to the full size image? Although I recognise the chip, and am very familiar with the patterns and shapes seen in this image, it isn't close enough to make out any detail or differences with the 6561E.

Hey, this is great! Thank you very much. I shall take a close look this evening.

Something is not right in this picture. There are two cables coming out of the computer, one for the datasette, and the other is apparently a video cable running to the television. So how is this machine powered? There is no power cable anywhere, and yet the computer is supposedly producing the ima...

Do we think that this effect is specific to the noise voice (and therefore an explanation would be within the noise part of the die shot)? Or could it apply to the sound in general (and therefore might be somewhere after the individual voice sections, or if not, then due to something common to all v...

When starting out with reversing a die shot, the first step is to identify what pins each of the bonding pads were connected to. The easiest bonding pads to identify are VDD and VSS. When viewing the metal layer, VSS/GND is connected to the metal around the edge of the chip. Looking at the 6522 die ...

Ok, so basically they are stored in flip-flops..or at least it looks that way. I do not understand the circuit you linked to though.. it looks like it only can put the circuit into one state (W high), while the other (W low) does not make much sense to me.. Maybe you could explain that one a little...

In the case of the 6522, we're fortunate to have access to two die shots, one with the metal layer still on, and one with the metal removed. Makes it a lot easier. And it will be purely digital. I have decided to create a topic to talk about reversing the 6522. Not sure how much time I'll dedicate ...

Wow!... Postimage has done a fine mess of this thread. I don't think I have any backup of all the scope captures in here... :( The Wayback Machine (web.archive.org) appears to have crawled some of them, but not all: http://web.archive.org/web/20160913200445if_/https://s32.postimg.io/9eez6spf9/8luma...

perhaps their first design was to make a multiple waveform device, then they converged to a more simple device, but instead of redesigning it completely they simply disconnected the unneeded parts. I recall that the 6562 datasheet mentions multiple waveforms, so it seems that they were experimentin...

And also... What are the "not used" sections of the tone generators.. Filters? Or has it something to do with the sound mixing? The following diagram shows the "not used" section of the tone generator. It is disconnected from the rest of the circuit. It is clear that at some poi...

I just discovered the other thread "FPGA replacement for VIC I chip?" where you discuss about colour generation! It's a quite lengthy thread so I haven't read it yet, but please can you tell me if we have a table of the VIC-20 color palette, or at least a way to calculate it ? I haven't p...

Here is a link to all the 37 pictures sofar (!! 117MB). These are 3 stripes of about 12 pictures each; e.g. about 25% of the chip. The rest I will have to do later as I am going on travel now. If you/anyone wants to mount these pictures together into a larger one, we would all be very happy. :wink:...

Could you also say something about how the control register values are stored. Probably not important, but for me it would be interesting to know Does this post from the old thread suffice? http://sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?f=11&t=7118&p=88489&hilit=Fpga+6561...

...and maybe one day I'll start looking at the 6522 die shot. :) A few days ago, I discovered for the first time bwack's VIC II die shot reverse engineering video series on Youtube. I know its strange that I didn't previously know about it given my own interest in reversing die shots. Quite a task ...