In rec.games.video.arcade.collecting Robert Bullock wrote:
: Speculations. The voltage was at 4.98 or so, and I still don't see where one
: part from one manufacturer that was old as the board would work where new
: ones would not. frankly, don't care.

The simple fact is that that circuit doesn't drive the 74ls368 with
valid TTL input levels. The resistors across the gates in the 368
result in the inputs being stuck at invalid TTL input levels, so the
output levels aren't guaranteed. If the crystal/cap don't provide
enough excitation to get enough feedback to start the circuit oscillating,
it's the circuit's fault, not the chip's fault.


: If the chip couldn't take 4.98 and work with it, it's bad.

Most of my pacs work down to 4.3 (and many below).

--
Mark Spaeth
50 Vassar St., #38.265
Cambridge, MA 02139
(617) 452-2354 http://rgvac.978.org/~mspaeth