Limited Precision Z-slopes
Compact 8-bit format:
- 1-bit sign
- 5-bit exponent
- Can represent 231 to 0
- Covers entire range of 24-bit Z value
- 3-bit mantissa (one bit is hidden)
With rounding max error is 1 part in 9
- .1001 is rounded up to .101
- .1000111… is rounded down to .100