In message <4387794F.1020008 at jetnet.ab.ca>
woodelf <bfranchuk at jetnet.ab.ca> wrote:
Allison wrote:
Either that a Dflop(74LS74), hex D-latch(74LS174)
and 32x4 prom(74LS288).
Just for the heck of it, got a schematic and a prom listing?
Did anybody ever use a serial chip and a data separater
rather than a floppy disk controler?
Actually, I wouldn't mind taking a look at the appnote with the data
separator in it. Sounds like something that might be worth reading...
I've just spent two days reverse-engineering the Atari Digital Vector
Generator down to state machine level. Thank %DEITY for schematics!
Only thing I am trying to work out is why the hell the state machine jumps to
state 9 on startup, which is a DMALD microinstruction. Basically, when it
starts up, it pulls an address off the stack and jumps to it. Unless I'm
wrong, that means it jumps to a random address on startup. That is, unless
the LS670 Register File Memory used for the stack is guaranteed to power up
with all registers loaded with 0000(bin), but IMO that's a dangerous
assumption to make without testing.
Just a shame LS670s are pretty much unobtainium these days, otherwise I would
have tested it out...
Thanks.
--
Phil. | Acorn RiscPC600 SA220 64MB+6GB 100baseT
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