Hallo Arif,

without oscilloscope you are totally blind. Nevertheless, an application can work nicely, if all timing specifications are analyzed, even when you never had a look with oscilloscope.

Your oscilloscope should have two inputs, because many times it's necessary to know, which signal comes first.

It should be a digital storage oscilloscope, because many signals don't have a periodicy and cannot be seen with an analog oscilloscope, without using some tricks.

Needed bandwidth of oscilloscope depends on your application. Let's have some calculation. Assume your mcu runs with 11Mhz, then pulse width of RD# pulse is about 500nsec. Assuming that this is one half of a square wave, this corresponds to a signal of about 1MHz. So, for 'detecting' RD# pulse, means, is it there, or not, an oscilloscope with very low bandwidth is enough. With 5MHz oscilloscope you would see the square wave, but edges are rounded.
But if you want to have a look at 11MHz oscillator signal situation is different. It's obvious that 5MHz oscilloscope would not be good enough, at all. Then you would need a much faster one. If you additionally want to see details of shape of edges of oscillator signal or RD# pulse you should use a 100MHz oscilloscope.
It's funny, like Steve I also bought this Velleman digital storage oscilloscope PCS500 last week. But I have not tested it up to now. It's 'only' 50MHz bandwidth oscilloscope, but having 1Gigasamples/sec. Price is very low, about 370 Euro!

There is still one important point. The connection of probe of oscilloscope to signal is extremely critical. Having a too long ground tip results in heavy ringing, giving you a totally wrong 'signal'. This is caused by inductivity of ground tip. Every cm counts!!
It's best to use these small adaptors, which can be put on the probe. (Heaven, my english is so poor...) These adaptors have a grounding 'needle' which is flexible and can be rammed into ground (0V of circuit) very close to signal to be measured. Here a PCB with ground plane extremely helps.

Bye,
Kai