soohoo@cory.Berkeley.EDU (Ken "nmi" Soohoo) (12/01/89)
There's been quite a few ponderings in the last few days about the possiblity of an STE shifter that's pin-pin compadible with the ST shifter -- I just wanna add my $0.02 ;-) The STE shifter outputs 4 bits of color per gun, which means that the DACs required to go to your video are gonna be different, no? It would mean Atari would have to lay out another chip that's an ST replacement shifter w/o the extra color bit... Seems kinda pointless for them, lots of R&D $$, little return, plus they'd need lots of packages to hit all the shifter versions out there... Sigh, that's the way it seemed to me, not likely to be an ST STE shifter out any time soon... --Kenneth "kens" Soohoo (soohoo@cory.Berkeley.Edu) Atari Hacker (Atari's Hacker...) "It could be worse, you could get hit by a bus..." My opinions are my OWN, _not_ necessarily Atari's. But "hey", who knows?
cbdougla@uokmax.ecn.uoknor.edu (Collin Broadrick Douglas) (12/02/89)
In article <20157@pasteur.Berkeley.EDU> soohoo@cory.Berkeley.EDU (Ken "nmi" Soohoo) writes: >There's been quite a few ponderings in the last few days about the >possiblity of an STE shifter that's pin-pin compadible with the >ST shifter -- I just wanna add my $0.02 ;-) > >The STE shifter outputs 4 bits of color per gun, which means that >the DACs required to go to your video are gonna be different, no? >It would mean Atari would have to lay out another chip that's >an ST replacement shifter w/o the extra color bit... Seems kinda >pointless for them, lots of R&D $$, little return, plus they'd >need lots of packages to hit all the shifter versions out there... > >Sigh, that's the way it seemed to me, not likely to be an ST STE >shifter out any time soon... > > >--Kenneth "kens" Soohoo (soohoo@cory.Berkeley.Edu) > Atari Hacker (Atari's Hacker...) > "It could be worse, you could get hit by a bus..." > My opinions are my OWN, _not_ necessarily Atari's. But "hey", who knows? Except for one thing. In Medium res the Atari get 16 colors per screen. I may be stupid but doesn't this already mean that the shifter has to output 4 bits (4 bits = 16 colors)? All they would have to change is the total number of colors available (from 512 to 4096). And that is just the difference of having more shades of the same colors. The primary colors (Red, Green A just my $.02 worth. Collin Douglas cbdougla@uokmax.ecn.uoknor.edu and Blue) each with 16 shades gives a total of 4096 colors (16^3).
soohoo@cory.Berkeley.EDU (Ken "nmi" Soohoo) (12/03/89)
In article <1989Dec1.183920.12339@uokmax.ecn.uoknor.edu> cbdougla@uokmax.UUCP (Collin Broadrick Douglas) writes: >In article <20157@pasteur.Berkeley.EDU> soohoo@cory.Berkeley.EDU (Ken "nmi" Soohoo) writes: >>The STE shifter outputs 4 bits of color per gun, which means that >>the DACs required to go to your video are gonna be different, no? >>It would mean Atari would have to lay out another chip that's >>an ST replacement shifter w/o the extra color bit... Seems kinda >>pointless for them, lots of R&D $$, little return, plus they'd >>need lots of packages to hit all the shifter versions out there... > > > Except for one thing. In Medium res the Atari get 16 colors per screen. I > may be stupid but doesn't this already mean that the shifter has to output > 4 bits (4 bits = 16 colors)? All they would have to change is the total > number of colors available (from 512 to 4096). And that is just the > difference of having more shades of the same colors. The primary colors > (Red, Green and Blue) each with 16 shades gives a total of 4096 colors > (16^3). >cbdougla@uokmax.ecn.uoknor.edu > Collin, You're confusing "bit planes" and "bits per gun"... Lemme explain: The number of bit planes in a specific resolution determines the number of color _table_ entries you can access for a given pixel in that resolution -- in Atari's low res case, 2^4 = 16, medium, 2^2 = 4, high 2^1 = 1... Ok, no each color table entry can be filled with a number that's going to determine which color is sent to the screen, and in the ST's case that number has 3 bits assigned to each RG^B, for a grand total of 2^9, or 512, colors possible to be assigned per color table entry... So you can have 16/512 colors on the screen at the same time without resetting the color table mid-screen... Oh, anyway, so the STE's shifter has the same number of bit _planes_ per resolution, but an additional bit _per RG&B gun_, so that each color table entry can be one of 2^12, or 4096 colors... SO now you can get 16/4096 colors on screen at the same time. A DAC takes the value in the color table entry and converts it from the 0's and 1's representation into a voltage value for the monitor. With an extra bit being sent to a DAC that only understands 3 bits, we have a fundamental problem, and unfortunately I don't think it can be ignored. --Kenneth "kens" Soohoo (soohoo@cory.Berkeley.Edu) Atari Hacker (Atari's Hacker...) "It could be worse, you could get hit by a bus..." My opinions are my OWN, _not_ necessarily Atari's. But "hey", who knows?
neil@cs.hw.ac.uk (Neil Forsyth) (12/04/89)
In article <20157@pasteur.Berkeley.EDU> soohoo@cory.Berkeley.EDU (Ken "nmi" Soohoo) writes: >There's been quite a few ponderings in the last few days about the >possiblity of an STE shifter that's pin-pin compadible with the >ST shifter <Details why not deleted> I'm not bothered about SHIFTER, it's MMU I want replaced. No palette changes just better hardware scrolling. >--Kenneth "kens" Soohoo (soohoo@cory.Berkeley.Edu) +-----------------------------------------------------------------------------+ ! DISCLAIMER: Unless otherwise stated, the above comments are entirely my own ! ! ! ! Neil Forsyth JANET: neil@uk.ac.hw.cs ! ! Dept. of Computer Science ARPA: neil@cs.hw.ac.uk ! ! Heriot-Watt University UUCP: ..!ukc!cs.hw.ac.uk!neil ! ! Edinburgh, Scotland, UK "spam spaM spAM sPAM SPAM, lovely SPAM" ! +-----------------------------------------------------------------------------+
jwt@atari.UUCP (Jim Tittsler) (12/09/89)
neil@cs.hw.ac.uk (Neil Forsyth) writes: >I'm not bothered about SHIFTER, it's MMU I want replaced. No palette changes >just better hardware scrolling. The scrolling features required revisions to both the MCU (since if you are not word-aligned you need to send (at least) one more set of words to the shifter per line) and the Shifter (so it could decide which pixel of the word to start on). Neither the STe shifter nor the new combined MCU/Glue can be directly plugged into an ST. Jim Tittsler, Systems Engineer (and alleged hardware type), Atari Corp.
buggs@cup.portal.com (William Edward JuneJr) (12/17/89)
>Neither the STe shifter nor the new combined MCU/Glue can be directly >plugged into an ST. >Jim Tittsler, Systems Engineer (and alleged hardware type), Atari Corp. BUMMER deal!