Maximum SiliconExpress IV Throughput

[eharmon]

Continuing my SiliconExpress experimentation, I've been doing some benchmarks on my Quadra 650 board with ZuluSCSI.

Read

Native SCSI	ZuluSCSI (RP2040)	4,700KB/s
SiliconExpress IV (8-bit) - 1.6.5	ZuluSCSI (RP2040)	8,123KB/s
SiliconExpress IV (16-bit) - 1.6.5	ZuluSCSI Wide	8,959KB/s

Write results are generally ~30% slower.

I need to try the SCSI 4.3 firmware to see if it's any different.

Wombat boards have a NuBus implementation that leaves a bit to be desired (no double data rate transfers @ 20MHz except between cards), which TIL 9305 implies should give you 8-10MB/s to the logic board and a theoretical 20MB/s out of the logic board (if the destination device could accept block transfers at zero wait). So that seems ballpark to what we're getting.

Still, surprisingly rough! So it seems on the earlier Quadras there's only a small boost from moving to 16-bit (~10%).

The official documentation always seemed ambiguous to me if later devices really supported 20MHz transfers to the logic board. Has anyone benchmarked a Quadra AV or 6100/7100/8100 and a SiliconExpress?

 

[Unknown_K]

I benched spinning disks ages ago on Jackhammers and SEIV (I have SEII's and other Nubus SCSI cards as well). There should be results from back then on the forum if you search.

 

[lobust]

An interesting data point - unfortunately I didn't document much of it - I did exactly what you've done here a couple of years ago with a SCSI2SD v6. What stands out to me is that I got the same results as you through the SEIV, but my native reads were significantly slower than yours at ~2800

I do have an 840av now and still have the SEIV, but I have little spare time for this kind of thing right now...

Here are my old threads on the topic, someone else posted some Q950 and PM8100 benchmarks in the SEIV one:

ATTO Silicon Express II Nubus

I recently bought one of these to try out - google turns up almost nothing about this card, so I thought I'd document what I've learned about it. 1. It is bootable, at least on a Quadra 650/800, haven't tried any others yet. It will not find a bootable disk on it's own, but if you boot by some...

tinkerdifferent.com

ATTO Silicon Express IV Nubus

I have read some comments here and there suggesting the Silicon Express IV is not bootable. I have just acquired one, and I can confirm that it IS in fact bootable, at least on a Quadra 800, which is the only Mac I have thus far tested it in. The same rules apply as with the SE II - it will...

tinkerdifferent.com