Hi,
Yes, the 08M2 has almost as many "features" as all the other PICaxes in this respect. The only difference I can think of is that the X2 chips give access to the "Negative" (lower) end of the Reference Voltage. Then the extended "practical" answers to your questions are:
1. It has only ONE ADC, but its input can be internally connected to any one of most/all of the "Analogue" pins via a Multiplexer (switch). Note that the ADC input is recommended to be fed from a
source resistance of no more than 10k (unless an input capacitor of perhaps 10nF to ground is added). The so called "Output Only" Leg 7 of the 08M2 can be also employed as an ADC input, where/when it is connected to the DAC (using the READ
DAC command). I've found this useful for monitoring a current flowing in to or out from ground by measuring the (low) voltage across a (usually very) low-valued resistor. A "negative" voltage measurement is possible by bleeding current out of the DAC pin from the DAC, which has quite a high (but, beware not constant) source resistance.
2. Yes it has the FVR (Fixed Voltage Reference) which has a temperature coefficient similar to a regulator like the 78L05. However, note that the specified ABSOLUTE accuracy is quite poor at about +/- 9%, so you should always include a "Calibration" stage to check and correct for the "actual" voltage.
3. Yes you can use
FVRSETUP ; FVR4096 is not very useful because it is quite close to the maximum supply voltage (so you'd probably be using a regulated supply anyway), but FVR1024 can be used with care, although not "officially" permitted in the Microchip Data Sheet.
(4.) CALIBADC can be a very useful command, to measure (also/alternatively) the voltage of the PICaxe's supply rail. FWIW, I've extended that method to monitor the supply rail to better than 1 mV
resolution (NOT Accuracy).
Cheers, Alan.
