[Coco] Bit 5 of DSKREG

[tim lindner]

Robert Gault <robert.gault at worldnet.att.net> wrote:
> 
> Tim,
> 
> There is most definitely a problem with making bit 5 both a density flag
> and an NMI flag. This is after all a single bit so it can only have two
> states, on or off. Making this both a density and NMI flag implies that
> the bit can have 4 states which is just not possible.

I am not saying the bit has four states. I am saying the single bit
controls two functions.

It also makes sense to me. A .89 Mhz CoCo should be fast enough to use
polling in single density operation. Though I havent tested it yet.

> There is no indication of this bit being an NMI flag/switch in the 
> "Unravelled" series, "The Facts for the TRS-80 Color Computer" (an 
> earlier unraveled version), or the Disk Basic owners manual.

Since single density operation is so rare on the CoCo, I don't trust
thoes references to get it right. Which is why I turned to the
schematics.

But, again, I could be wrong.

-- 
tim lindner
tlindner at ix.netcom.com                                            Bright