Path: utzoo!utgpu!news-server.csri.toronto.edu!qucdn!leek Newsgroups: comp.sys.amiga Subject: Re: Fast clocks... Organization: Queen's University at Kingston Date: Thursday, 26 Jul 1990 18:39:40 EDT From: Message-ID: <90207.183940LEEK@QUCDN.BITNET> References: <4975@uafhp.uark.edu> <13438@cbmvax.commodore.com> In article <13438@cbmvax.commodore.com>, rsbx@cbmvax.commodore.com (Raymond S. Brand) says: > >Normally, the E-clock doesn't change too much, there is a value for NTSC >systems and a different one for PAL system, and they're within 1% of each >other.What you've done is changed the system E-clock frequ >should be and confused the timer.device. > >Fixes: > Undo your hack (uh, I didn't think so..... :-) > > Build a divide-by-10 circuit to generate the E-Clock from the OLD > processor clock. > > Build a divide-by-2 circuit to generate the E-clock from the E pin > of you speedy processor. > That's should get the right frequency for the E clock, however the E clock is also used to do 6800 style perpherial chip access in the 8520s. The E clock has somehow be sync to the 6800 bus cycle for proper operations, doesn't it ?? Looks like the job for some PAL chips to generate all the timing info + bus signal for a 6800 perpherial access. That's the way the Lucas 68020 accelerator works - a 68020 do not support 6800 perpherials, so Brad Fowles make one out of a regular memory access. >------------------------------------------------------------------------ > Raymond S. Brand rsbx@cbmvax.commodore.com > Commodore-Amiga Engineering ...!uunet!cbmvax!rsbx > 1200 Wilson Drive (215)-431-9100 > West Chester PA 19380 "Looking" >------------------------------------------------------------------------ K. C. Lee P. S. For those interested, the Lucas article is in the now nonexistance Amiga Transactor Volume 1, issue 3 P. 36-43. Pal equations are included.