To find the diameter of the cylinder, we can use the formulas for Curved Surface Area (CSA) and Total Surface Area (TSA).

1. Identify the Formulas

Curved Surface Area (CSA) of a cylinder: $2\pi rh$

Total Surface Area (TSA) of a cylinder: $2\pi rh + 2\pi r^2 = 2\pi r(h + r)$

(where $r$ is the radius and $h$ is the height)

2. Set up the Equation

The problem states that the curved surface area is half of the total surface area:

$$CSA = \frac{1}{2} TSA$$

Substitute the formulas into the equation:

$$2\pi rh = \frac{1}{2} [2\pi r(h + r)]$$

3. Simplify the Equation

Cancel out $2\pi r$ from both sides (since $r \neq 0$):

$$h = \frac{1}{2}(h + r)$$

Multiply both sides by 2:

$$2h = h + r$$

$$r = h$$

4. Calculate the Diameter

We are given that the height ($h$) is 195 cm.

Since we found that $r = h$, the radius is:

$$r = 195\text{ cm}$$

The diameter ($d$) is twice the radius:

$$d = 2r$$

$$d = 2 \times 195 = \mathbf{390\text{ cm}}$$

Final Answer:

The diameter of the cylinder is 390 cm.