On 2011-08-09 20:40, Gerrit Heitsch wrote: > On 08/09/2011 07:34 PM, Hársfalvi Levente wrote: > [......] > Could be, but then I have seen at least one board with a 7501R1 from > 1984 and a 8360 from 1986 so the production year of the TED doesn't mean > much in respect to the CPU. I wouldn't be surprised if at the end they > just threw together what they had. Yeah, possibly... >> Not sure (never seen die photos of these newer models), but some bits of >> the onboard CPU I/O port are unimplemented in these three CPUs, and the >> bit positions (ie. exactly which bits are unimplemented) don't match - >> I'm assuming they'd have at least had to customize the chips before >> packaging, which looks unlikely. > > The idea I had was that the die inside the package has more than 40 pads > including a full 8 Bit port and all the other signals. So that when > bonding the die the machine can be programmed to produce the desired > pinout... It would have made production cheaper since you only needed > one mask set for all 3 CPUs. The problem is - these bits really "don't exist", to the point that you can detect their absence from the ports by code. If the die had a full 8 bit port, you'd need to be able to set/reset the "missing" bits in at least the data direction register (and also in the data register, at least, if the respective bits were previously defined as outputs), regardless to the fact that these port bits were unconnected to the package pins. Contrary to that, at least on the 8501 (whose I/O port lacks bit5) the missing bit would always read back 0 in both the DDR and the data register (regardless of any attempts to set them to 1). >>> Finally, if anyone here has a defective TED and is willing to donate it, >>> contact the folks at http://visual6502.org they are looking for one to >>> depackage and take high resolution photographs of the die. >> >> I've got a couple of them for sure :-) (even more 8501s, but, err... :-D >> ), no problem if they're really looking for some... > > Just contact them... I mailed them a broken 8501 a few weeks ago. When > they get around to depackage it and upload the photographs we might find > ouf whether my theory of 'one die for 8500/1/2' is correct or not. > > I'd like to see a VIC-II and TED hi res die shot side by side. Since > some of the display tricks from VIC also work on TED, I expect to see > some parts looking identical. > Contacted them, will see what happens (also seem to have a 6529B and probably a 8551 for that purpose... who knows...). As I can see they already have the 6561 + some revisions of the VIC-II... that's gonna at least make a nice possibility to see how things "evolved"... (I can see a significant difference between the image quality provided by the chips as they evolved... it's been IMHO a great idea to generate a composite video signal on a single NMOS chip, and it'd be nice to see how they perfected that from the early VIC-Is from the TEDs and late 856* VIC-II-s... ) > Gerrit Levente Message was sent through the cbm-hackers mailing listReceived on 2011-08-10 20:00:08
Archive generated by hypermail 2.2.0.