plgDavid wrote:I was interested in this ever since its mention in Bagnall’s book.
...
The first edition Bagnall "company over the edge" book had a whole section on the 6560 dev and how MOS wanted to find companies interested in using the chip, and that in the end it was only used in "one Japanese Space invaders clone" or a similar wording (from memory). Nothing more but was enough
plgDavid wrote:
Whether its a pre release VIC-I or custom mod is anyone’s guess.
lance.ewing wrote:
Hmmm, yeah, given they were initially targeting buyers such as arcade machine designers, then perhaps this is pre the version we're familiar with.
After reading a bit of the Bagnall book, and getting up to the bits that discuss the 6560, 6562, and 6564, I'm starting to think now that the 6560 in the Attack UFO game is the original 6560 chip designed back in 1976 and completed in 1977.
The way in which the chronology of events is presented in the book suggests that the Japanese company (Ryoto Electric) had already bought the chip prior to the big push by Tramiel for his engineers to produce the TOI, which lead to the work on the 6562 and 6564. The 6562 was basically a 2-week hack of the original 6560 to make it support 40 columns and seems to have been abandoned almost as quickly due to the dependence on expensive RAM. The 6564 was worked on for a lot longer but couldn't be made stable enough. However, the colour generation from the 6564 was fitted back into the version of the 6560 used in the VIC 20. This seemed to be happening towards mid 1980. The MicroPET prototype (i.e. the concept that lead to the VIC 20) was unveiled to Tramiel in May 1980, and although it might have already had the modified 6560 in it, it is unlikely given the timing (and sensitivity of the MicroPET) that Ryoto Electric would have ended up with that version. So Attack UFO must surely have the original unmodified chip. There is no discussion in the book about producing customisations for customers, only that they struggled to sell the original chip, other than to the Japanese arcade game company.
I hadn't thought about this before, but that means that the colour generation logic that I was looking at back in my die shot posts last year originally came from the 6564. Yannes added the multi-colour mode as part of the 6564 work while Charpentier was improving the colour generation itself in the 6564 work. The whole of the 6564 video system seems to have been dropped back into the original 6560, so that is what we're seeing in the 6561 die shot. There is also a suggestion that the sound generation may have been updated, but I'm not certain about that.
I would so love to see a die shot of the Attack UFO 6560. That must be the earliest form of the 6560 rather than being customised. It seems that it isn't that the multi colour mode was disabled, but rather that it hadn't been added yet. Maybe we'll have to wait until one of these Attack UFO PCBs out there stops working due to a video issue and then convince the owner to send it to Kakemoms or John McMaster.
It is interesting that the 1981 Commodore Component Data Catalog has both the 6560 and 6562 in it. This doesn't quite tie up with what the Bagnall book says. The book implies that the 6562 was being worked on for a few weeks prior to a show in early 1980 and was abandoned not long after. The 1981 Catalog suggests that they were still willing in 1981 to sell it to people who happened to want it. The requirements to use it were too expensive for Commodore themselves to use it in a home computer. I assume since they'd designed it, they thought they may as well put it in the catalog in case someone wanted to buy it.