Hi,
@anybody interested ;-)
I have successfully installed the SCSI-II controller-IC (WD33C93B-PL) into my A3000T :-D.
After I've got this chip via eBay, I searched the web for experiences with this SCSI-chip as replacement for the original WD33C93A-PL (PROTO). I've found two kinds of meanings, but no real experiences.
The first group of users said that there is no way to get this chip to work in an A3000 because the Super DMAC and the scsi.device doesn't match the requirements/commandset of this chip.
The others said that there is a great perfomancewin by using this chip.
Now I've made my own experences (and performed some tests).
First of all: The chip does work. I don't think that it really performs as an SCSI-II device, but the chip seems to be backward compatible :-)
Second: There is a measurable performance win :-D
The speed-improvement is not very high, it depends in the size of the blocks transfered in a single read or write. The larger the blocks, the higher the performance win.
If 512 byte blocks are transfered the win is zero, if using 4KB blocks the win is upto 5% (read and write) and with 64KB blocks the win is higher than 5%.
(I've tested with my 2.1GB IBM UltraSCSI harddisk and an external Syquest 200MB removable harddisk).
My top-result is the write-speed of the Syquest drive: Using 64KB blocks, the write-speed is more than 40% higher with the new SCSI-chip :-D
If you ask me, I would say this is worth the replacement (and the bus-hangs with the old controller should also be gone).
Noster
