paulba@teklabs.UUCP (09/20/83)
Before I knew about the SAM chip, another fellow employee and myself had decided to interleave a MC6847 with a MC6802. We were successful, BUT we found out that the MC6847 was ( now get this ) EITHER EDGE TRIGGERED on it's clock input. It seems that on power-up it decides which edge to use. Could it be that this is related to the coco color problems ??? teklabs!paulba
dya@unc-c.UUCP (09/21/83)
References: teklabs.2470
....Interestingly enough, I had the same problem (either edge triggered)
using a totally unrelated IC, the TRW TDC1007J (flash A/D). But its
either-edge-triggeredness really wasn't here, it was how I was generating
the system clock (delay line XOR-multiplier). The state this circuit
comes up in can really mess up your mind; if you've got state of the
art VLSI in one place and even faster STTL in the other.
....Could it be that the CoCo generates system clock by multiplying up
the colour burst (63/88 * 5 000 000; ~~ 3.58 mc) using same said circuit?
Is it getting into a funky state on power up due to the indeterminacy of
how the {insert-your-rate-muliplier-here} comes up ?? Eagerly awaiting
answers..
--David Anthony-- { ...mcnc!unc-c!urp!dya }