Z80/R800/Z180/Z380 MPU Comparison Chart
| Z80 | R800 | Z180 | Z380 | |
| External Data Bus Width | 8-bit | 8-bit | 8-bit | 16/32-bit |
| Address Space | 64k | 64k | 1Mb | 16Mb Linear |
| Number of register sets | 2 | 2 | 2 | 8 16-bit |
| Number of register planes | 1 | 1 | 1 | 4 |
| Static core | no | no | yes | yes |
| CPU Speed | 3.57 | 7.14 | 33 | 18 |
| Clocks/Inst. Min | 4 | 1 | 3 | 2 |
| Relative Performance | 1 | 7 | 11 | 9 (33) |
Note: ZiLOG themselves rate the Z380 with a relative performance of 33 because of the 32-bits extended instruction set and all the other added features. However, although it does deserve a slightly higher rating because of that, in practice this 33 is pretty over the top. I’ll just stick with the CPU speed / min. clockticks indication :).