Hi. Anyone attached to this thread still active here?
. I do see that Mike has recent posts elsewhere. I realize it is possible after all this time you do not even have any of the same Amiga equipment you once had.
I will make the unpopular decision to add to this 13 year old post for the proper context.
Mike, it wasn't clear from your previous posts if you tried to use GVPSCSICtrl to put the accelerator's SCSI into synchronous mode. According to all my research, this is the key to improving transfer speed. I believe you were convinced you had to try another SCSI controller in your system because you had better results with stand-alone GVP SCSI cards.
However, being able to actually use synch mode is more challenging I have learned.
First, a little brief history on my situation-- I have a 33MHz GeForce 040 I picked up back in Feb '23. Some time later, I obtained the GuruROM 6.16. My motivation for getting it wasn't necessarily for a performance boost. I think I was more interested in compatibility at the time since I had plans to use external SCSI devices. I later learned I could enable the SCSI's synchronous mode and that it was better than what the original ROM could offer. My '040 board's original drive was a scsi2sd directly attached to the board using the old mounting bracket and a very short SCSI cable. GuruROM replaces "gvpscsi.device" with "omniscsi.device". Since the SCSI defaults to asynchronous mode by default on startup, I had to enable it in the startup-sequence using the command "OmniSCSICtrl 0 synchronous". "0" referring to the number of my scsi2sd card.
After making this change, I was disappointed that my speed increased only marginally. I think I started at 1.9 MB/sec and went to 2.0.
The theoretical max is 5MB/sec for the 8 bit SCSI 1 used in the GeForce 040. The real-world speed in synch mode (going back to rotational drives) is anywhere between 3 - 4.5 MB/sec. On top of this disappointment, I was also receiving random read errors. Temporarily disabling the sync didn't actually solve the problem I later found out.
Fast forward to Nov '24, I purchased a ZuluSCSI card with plans to mount it in a 3D printed bracket that will sit in my floppy drive bay. This is a combo bracket that included a space for my Gotek drive as well. This all worked out well. The ZuluSCSI had the benefit of using drive files instead of seeing the entire media as a single large drive. Although, it had the advantage that I could still configure it like the scsi2sd if I wanted to. The convenience of ZuluSCSI's file based drives allowed me to finally create stable boot and expansion drives for use with ShapeShifter. I was also having success using other Amiga software, playing demos and games.
This brings me to the present. Having achieved a stable system for the most part, I realized I was falling behind on firmware updates for the ZuluSCSI. Trying to install the latest firmware was failing despite following the same steps I took in the past. After exchanging words with Alex on Github, I learned that my particular ZuluSCSI card was losing support for new code additions because it lacks features in hardware. It was possible to release the code that was still compatible and he posted a firmware release that would work for me. Following this news, I set out on a new ZuluSCSI acquisition. I will spare you those details for now except to say I still have the ZuluSCSI v1.2 connected at this time.
AND, OHHHHH-- I finally made an important change to my GVP board that I should have done long ago the moment I decided to use external devices-- I removed the internal resistor packs! Yes, this was a likely cause of those "random" errors I was still getting. After removing the resistor packs and ensuring that my external SCSI drive was terminated, I tested out many demos for a few hours...not a single error popped up. Did I finally put this to rest? Maybe.Phew! I know, I know....long post so far. Please bear with me.
In conversations with others, something dawned on me. I realized I still had that sync mode entry commented out of my startup-sequence. I also realized device ID 0 was meant for my old scsi2sd card. I did not have a drive file configured for that device number in my ZuluSCSI! Just re-enabling the sync command would have had no benefit. I did some shuffling of drive number assignments and made my AmigaOS boot drive unit 0. After enabling synch mode in an open shell, I saw an immediate improvement with how fast my icons were displaying. Woo hoo! I edited my startup-sequence to re-enable synch......and rebooted. BAM! I am hit with hard read errors on start. Then the drive came up as NON-DOS! Fortunately, I had a recent backup drive so it was restored right away. Sigh.
Sooo.....I am left wondering if sync mode has ever worked for *anyone* given that I have an ideal setup from which to enable it.
Researching this subject on the interwebs hasn't revealed any hard solutions, only other suggestions. One that does sound promising and makes sense is that I need to enable TERM PWR on the GeForce 040 so that I can use ACTIVE TERMINATION. The board has this ability but you need to solder on some components. I have no problem doing this but without finding any other reports of a) someone actually doing this mod and b) solving the problem, I am left hesitant.
Something that boosts my confidence that it will help is that I have TERM PWR enabled on my Amiga 3000. It more easily supports enabling synchronous transfers, and with the ZuluSCSI installed, I am getting 3.8MB/sec on my FFS System drive. SysInfo reports the ridiculous speed of 6.5MB/sec on my PFS3 volumes so I assume it is a pleasant inaccuracy seeing as how the most I should be able to achieve is 5MB/sec. The PFS3 drives do "feel" faster though.
