> ] cpu0 at mainbus0: TMS390Z50 v0 or TMS390Z55 @ 75 MHz, on-chip FPU
> ] cpu0: physical 20K instruction (64 b/l), 16K data (32 b/l), 1024K external (3
> }2 b/l): cache enabled
> ] 
> 
> Yes, that is exactly what my dmesg says,  the prom says something entirely
> different on boot. 

Ok, I just did a diag boot of my SS20.

>            SMCC SPARCstation 10/20 UP/MP POST version VRV3.43 (01/09/95)
> 
> 
> CPU_#0       TI, STP1021APGA(2.x)       1Mb External cache
...
> SPARCstation 20 (1 X SuperSPARC-II), No Keyboard
> ROM Rev. 2.22, 288 MB memory installed, Serial #7819401.
> Ethernet address 8:0:20:77:50:89, Host ID: 72775089.

I got:

Cpu #0 TI,TMS390Z55 
Cpu #1 Nothing there 
...

SPARCstation 20 (1 X 390Z55), No Keyboard
ROM Rev. 2.19, 160 MB memory installed, Serial #7493664.
Ethernet address 8:0:20:72:58:20, Host ID: 72725820.

I just lifted the lid and the heatsink on the cpu says SuperSPARC II,
the part No on the silicon below it is TMX390Z57GF

Whether it is actually running at 75MHz - who knows.

--sjg