Is SCSI Installation Possible

Eli Duttman · Posted: Mon Nov 04, 2019 2:23 pm Post subject: Is SCSI Installation Possible

This leads me to believe that Gentoo is a candidate OS for reactivating some "ancient" ISA bus hardware of mine. My CPU & RAM situation is similar, but the HDD and optical drive are SCSI. Can this be accomplished? Avoiding Win 9x is my object.

Like the young gentleman, I will generate Gentoo for the old hardware on a much faster, modern, PC. The clever trick of using a flash disk for "sneaker net" is (AFAIK) not available to me. I want to burn a DVD and boot it on the target hardware. My intention is to use GRUB4DOS, which I have some experience with, instead of the LILO the youngster used, in the boot loader role.

TIA for responses.
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Eli D.

krinn · Watchman Joined: 02 May 2003 Posts: 7471

by installing gentoo you will compile a kernel for the needed computer, which mean adding support for your scsi card
your only problem is the same as them, having a way to boot to install gentoo (something they bypass by booting on their laptop to install gentoo using it), which mean either having another computer, or a cdrom that boot a linux with a kernel that was built with your scsi card support.

NeddySeagoon · Posted: Mon Nov 04, 2019 2:36 pm Post subject:

Eli Duttman,

Welcome to Gentoo.

All the old ISA drivers are still in the kernel, so yes you too can do that.
What hardware are you installing on?

You may need to make your own boot media but I have some old things that may help.
With a bit of raking around I may have older things still too. :)

How good is your memory?
Can you still remember how to pass IO ports, DMA and IRQ to kernel modules?
ISA Plug and Pray was never very good and is best disabled, even if you have it.

All the old Gentoo documentation is still online in CVS. Its all in Guide-XML format, which is ugly to read.
The XML to http render engine went offline years ago.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Tony0945 · Posted: Mon Nov 04, 2019 4:18 pm Post subject:

Oh! wow! Your link is awesome! You even have stage 3 for i486!
What a treasure trove. I might try installing on my old first PC (486DX-100). It had 16G memory. Or was that 16 Meg?

NeddySeagoon · Posted: Mon Nov 04, 2019 4:43 pm Post subject:

Tony0945,

Together with the method for regressing both CVS and git I used to update an eight year old install, anything is possible. :)

The hard bit is finding distfiles
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

krinn · Watchman Joined: 02 May 2003 Posts: 7471

Eli Duttman · Posted: Mon Nov 04, 2019 10:55 pm Post subject:

Thanks to all who have replied.

NeddySeagoon · Posted: Tue Nov 05, 2019 12:05 am Post subject:

Eli Duttman,

You may qualify for this :)
The link in that page is broken but its here.

If this is to be your first Gentoo install. Hardware that old is not a good place to start.
You are going to need a way to build for it, but you have recognised that. Get a more mainstream install under your belt by way of learning first, then come back to this project.

That the on board IDE maxs out at 528MB is the reason that we have a small /boot partition at the front of the drive these days.
The files that are needed to boot are loaded by the BIOS. The 528Mb restriction apples. Once the kernel is in charge, the BIOS is not used.
However, some BIOSes won't boot when they have HDD bigger than they can cope with attached. Drives contemporary with those BIOSes usually have a jumper to make them lie about their size to the BIOS :)

My 5.3.8 kernel knows about your SCSI card

Tony0945 · Posted: Tue Nov 05, 2019 1:55 am Post subject:

Eli Duttman · Posted: Tue Nov 05, 2019 1:57 am Post subject:

There are 2 versions of the VTI "Topcat" chipset: 1 for 286s or 386SXs and the other for 386DXs. I have the latter, 3 IC, version. The vendor who sold me the SBC fitted the 486-33DX plus adapter into a 386DX PGA socket. The IBM/Cyrix 586 is pin compatible with the 486DX, but it runs on "3" V. not 5 V. The 586 came with an adapter plate that takes care of the voltage issue.

Even using a 128 MB boot partition doesn't deal with the slowness of that old (PIO) IDE interface. Even EIDE is slower than a true bus mastering SCSI controller that can maintain an honest 10 MB/S. data rate. PATA didn't begin to challenge SCSI speed, until UDMA came along. The AHA1542's BIOS extension hooks INT 19 and never had that 5nn MB issue, to begin with.

The Sound Blaster 16 SCSI, is (other than that PITA ASIC) rather typical of Creative's early 16 bit offerings. The SCSI ASIC consumes DMA, IRQ, & I/O port resources, "come Hell or high water".

A boot ROM is not present and, other than a 2nd optical drive, the ASIC has little (if any) practical use. A compact flash 1/2 height "drive", with a SCSI interface, would be nice, but (AFAIK) doesn't exist. Sadly, SCSI is close to Dodo status.

I think GRUB4DOS can be squeezed onto a 1.44 MB floppy disk. Unfortunately, GRUB4DOS can only hook IDE optical drives. Booting a SCSI optical drive requires (AFAIK) a properly set up ROM.
_________________
Eli D.

NeddySeagoon · Posted: Tue Nov 05, 2019 9:39 am Post subject:

Eli Duttman,

Consider /boot only on the internal IDE. Anything and everything else can be on SCSI.
Its read once at startup and written only when you update your kernel. Its speed won't be a problem.

SCSI has always used LBA. PC HDD used CHS addressing to start with and that was always a mess. Its selling point was that it kept the drive electronics simple (read low cost).

That sound card says Data Bus 16-bit ISA. That's what the kernel will see.
The card will provide a (usually butchered) SCSI interface for the CDROM.

SCSI over a 16 bit ISA bus is no better than IDE over the same bus. Its the bus speed that's the bottleneck.
SCSI should use less CPU as it supports DMA. IDE will only be PIO.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Eli Duttman · Posted: Tue Nov 05, 2019 10:44 pm Post subject:

NeddySeagoon,

What you say will definitely get mulled over. Some additional info.: when the switch to 486 was made, overheating was a serious problem that was corrected by a CPU fan. Heat is going to be an even bigger issue, when the 586 goes in. The Compaq chassis started with 2 full height drive openings. I have a HDD cooling fan that fits a full height opening, which should dispose of the air flow issue. That leaves only a pair of 1/2 height openings (I have full height opening adapter plates) for drives. My scheme is to mount a 1/2 height 3/5 combo floppy drive (already there) plus a SCSI optical drive in those 2 openings and mount the SCSI HDD in an external chassis that was previously used for an obsolete tape backup. Placing the HDD in an external chassis has the added benefit of easing the burden on the main power supply. While highly improved over Compaq's OEM stuff, that supply is well under 200 W. in capability.
_________________
Eli D.