I did, for my sins, help proof this document, so errors like this are really my fault.

But if we are starting....

13.2 Oscillator Inputs (XTAL1, XTAL2) .......................
... While a crystal is the normal clock source, this isnít necessarily the case. A TTL clock source may also be attached to XTAL1 and XTAL2 to provide the microcontrollerís clock.

I would say....

13.2 Oscillator Inputs (XTAL1, XTAL2) The 8052 is typically driven by a crystal connected to pins 18 (XTAL2) and 19 (XTAL1)Two small burden capacitors must beconnected from XTAL1 and XTAl2 to ground, typical values of these capacitors is approximately 33pF, but it depends on the crystal. Common crystal frequencies are 11.0592Mhz as well as 12Mhz, although many newer derivatives are capable of accepting frequencies as high as 40Mhz. While a crystal is the normal clock source, this isn't necessarily the case. A TTL clock source may also be attached to XTAL1 to provide the microcontroller with íts clock.

and in the next section on the reset pin.

The reset line is often connected to a reset button/switch that the user may press to reset the circuit. It is also common to connect the reset line to a watchdog IC or a supervisor IC (such as MAX707). The latter is highly recommended for commercial and professional designs since traditional resistor-capacitor networks attached to the reset line, while often sufficient for students or hobbyists, are not terribly reliable.

I would extend with a warning......
...and the use of R-C resets is a deadly error with FLASH based microcontrollers.


Steve