[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Apple IIc plus RGB video?

bieling@terra.es wrote:

Michael J. Mahon wrote:


Jorge Chamorro Bieling wrote:


But, IIRC, the signals available at the video output connector of a
Laser128 are not equal to the (estrambotic) ones in a IIc. They are more
like the IIgs.


OK, I give up--what does "estrambotic" mean?  ;-)



Estramb�tico : outlandish, eccentric, bizarre :
"conspicuously or grossly unconventional or unusual"

In other words, what came to my mind the first time I reached for the
IIc video connector pinout and found things like:

1- TEXT Video text signal from TMG; set to inverse of GR, except in
double high-resolution mode.
4- SEGB Displays vertical counter bit from IOU pin 4; in text mode,
indicates second low-order vertical counter; in graphics mode,
indicates low-resolution. 6- LDPS* Video shift-register load enable
from pin 12 of TMG.
9- PRAS* RAM row-address strobe from TMG pin 19.
10- GR Graphics mode enable from IOU pin 2.
11- SEROUT* Serialized character generator output from pin 1 of the
74LS166 shift register.
14- VIDD7 From 74LS374 video latch; causes half-dot shift high.

Instead of the much more friendly:

RED VIDEO / RED GND
GREEN VIDEO / GREEN GROUND
BLUE VIDEO / BLUE GROUND
HSYNC/CSYNC
VSYNC
GROUND


It probably would have been better for them to call it the "video
expansion" connector, and choose something other than a 15-pin
D connector.  ;-)

What they did was provide everything you would need to do your
own RGB--or whatever--conversion outside the box.  And several
manufacturers, including Apple, did that.

Maybe they were just trying to save cost, or maybe PC board
space got tight...

-michael

Music synthesis for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it is seriously underused."