jbardell wrote:
the MicroKim kit @ 100 dollars is actually a pretty good deal.
True. Plus, it's just so darn
cute !!Just thinking out loud about what display device you might use... Would you simulate NTSC video (per Lancaster) and use a television style monitor? Alternatively, VGA is a (pseudo-)standard that'll likely be around for a long time to come, but the horizontal scan frequency is double that of NTSC, so you'd have to adjust for fewer characters per line or else soup up your Micro-Kim to run at 2 Mhz instead of 1.
As for Garth's video scheme, it certainly has some major advantages -- notably the vastly simpler wiring. That has to be balanced against other factors, of course. The Micro-Kim lacks a 6522, so you'd have to add that somehow. A more serious issue, perhaps, is that the more characters you display, the slower the refresh rate becomes -- and thus the worse the flicker. With a 1 Mhz 6502 and 6522 this could become a serious annoyance -- I don't know. Garth?
GARTHWILSON wrote:
The tolerances of the msb resistor values would have to be about 0.2%. Maybe you could just add trimmers in series to those and live with 1% resistors.
Yeah, I guess to build a resistor DAC there
would be some fussing involved, although not
too bad. Years ago I built a pair of resistor DACs, and had instant success. But that was with the advantage of using a set of high-precision resistors salvaged from a
Linotron phototypesetter ![Very Happy :D](./images/smilies/icon_biggrin.gif)
BTW I see your point about the 12V supplies -- it's really not a big deal to provide those.
-- Jeff
ps -- going out of town for a coupla days... Might not hear from me