Intel486dx33 wrote on 2020-07-16, 12:39:

What is a good 50-pin SCSI controller for a 386/486 computer ?
This will be for a SCSI CDROM and maybe hard drive.
I don’t need SCSI floppy.

Adaptec AHA-1542 springs to mind, if you intend to use it in an ISA slot . If using a PCI 486, an Adaptec AHA-2930 or AHA-2940 is an option. VLB SCSI cards are rather expensive and rare and I have never used one .

Whatever you get, make sure it has a BIOS if you want to be able to boot from it .

If you have more than 16MB of memory I'd recommend one of the AHA-152x or 153x instead. The 1542 is an awesome adapter, but its best feature of using bus mastered DMA bites you in the ass if you have more memory than the ISA bus can address. You are then forced to use double buffering which kills performance

maxtherabbit wrote on 2020-07-16, 14:12:

If you have more than 16MB of memory I'd recommend one of the AHA-152x or 153x instead. The 1542 is an awesome adapter, but its best feature of using bus mastered DMA bites you in the ass if you have more memory than the ISA bus can address. You are then forced to use double buffering which kills performance

Good point, though, it should still be OK if the motherboard BIOS has a sub-16MB memory hole option, I imagine .

I use a AVA-1505 with my 386 for the CD-ROM it works great in DOS.

kingcake wrote on 2020-07-17, 00:37:

I use a AVA-1505 with my 386 for the CD-ROM it works great in DOS.

But there's no BIOS on AVA-1505, right?
So, good enough for CD-ROM, but bad for HDD.

Grzyb wrote on 2020-07-17, 01:41:

kingcake wrote on 2020-07-17, 00:37:

I use a AVA-1505 with my 386 for the CD-ROM it works great in DOS.

But there's no BIOS on AVA-1505, right?
So, good enough for CD-ROM, but bad for HDD.

good for HDD, bad for BOOT 😀

Darry,

I just bought a AHA-1542, but I can’t seem to boot from it. It always looks for the OS on the floppy. After booting from there, I can then see the SCSI drive. If I don’t put a floppy there at boot, it just sits and does nothing.

Can you help?

darry wrote on 2020-07-16, 13:07:

Intel486dx33 wrote on 2020-07-16, 12:39:

What is a good 50-pin SCSI controller for a 386/486 computer ?
This will be for a SCSI CDROM and maybe hard drive.
I don’t need SCSI floppy.

Adaptec AHA-1542 springs to mind, if you intend to use it in an ISA slot . If using a PCI 486, an Adaptec AHA-2930 or AHA-2940 is an option. VLB SCSI cards are rather expensive and rare and I have never used one .

Whatever you get, make sure it has a BIOS if you want to be able to boot from it .

Max,

Would you be willing to look at my post above?

maxtherabbit wrote on 2020-07-17, 02:06:

Grzyb wrote on 2020-07-17, 01:41:

kingcake wrote on 2020-07-17, 00:37:

I use a AVA-1505 with my 386 for the CD-ROM it works great in DOS.

But there's no BIOS on AVA-1505, right?
So, good enough for CD-ROM, but bad for HDD.

good for HDD, bad for BOOT 😀

1542 comes with on board bios.
You need to enable floppy drive from its jumpers or switches.
Floppy drive needs to be enabled and from motherboard bios.
Use system disk.
Recreate the master boot record (frisk /mbr).
Create primary partition (frisk util).
Format it.
Transfer the system (sys c:).
Set in BIOS to boot from c drive, or disable floppy entirely including from from scsi switches.
Done.

You won't be able to reuse existing partitions,so the above steps are mandatory.
This part of scsi is annoying.

guyewhite wrote on 2021-11-19, 04:08:

Max,

Would you be willing to look at my post above?

maxtherabbit wrote on 2020-07-17, 02:06:

Grzyb wrote on 2020-07-17, 01:41:

But there's no BIOS on AVA-1505, right?
So, good enough for CD-ROM, but bad for HDD.

good for HDD, bad for BOOT 😀

I found this in the installation guide for the 1542C:

If Your Computer Will Not Boot From a SCSI Disk Drive:
...
6. Make sure SW5 on the AHA-1540C is in the On/Closed position. It must remain in that position, even though there is no floppy controller on that host adapter.

I'm trying to boot from a SCSI2SD. Do I need to add it in the system bios?

Once I figure this out, I'm going to be writing a long how-to document. Many more steps than I expected.

maxtherabbit wrote on 2021-11-19, 13:51:

guyewhite wrote on 2021-11-19, 04:08:

Max,

Would you be willing to look at my post above?

maxtherabbit wrote on 2020-07-17, 02:06:

good for HDD, bad for BOOT 😀

I found this in the installation guide for the 1542C:

If Your Computer Will Not Boot From a SCSI Disk Drive:
...
6. Make sure SW5 on the AHA-1540C is in the On/Closed position. It must remain in that position, even though there is no floppy controller on that host adapter.

guyewhite wrote on 2021-11-19, 04:05:

I just bought a AHA-1542, but I can’t seem to boot from it. It always looks for the OS on the floppy. After booting from there, I can then see the SCSI drive. If I don’t put a floppy there at boot, it just sits and does nothing.

Can you help?

Possibly there is no proper boot code in the MBR of the SCSI drive. Try rewriting the boot code using "FDISK /MBR" when you booted from floppy.

That was the solution! THANK YOU!

mkarcher wrote on 2021-11-19, 23:26:

guyewhite wrote on 2021-11-19, 04:05:

I just bought a AHA-1542, but I can’t seem to boot from it. It always looks for the OS on the floppy. After booting from there, I can then see the SCSI drive. If I don’t put a floppy there at boot, it just sits and does nothing.

Can you help?

Possibly there is no proper boot code in the MBR of the SCSI drive. Try rewriting the boot code using "FDISK /MBR" when you booted from floppy.