Professional IRIS 4D/50, Clover 1 graphics - Printable Version

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RE: Professional IRIS 4D/50, Clover 1 graphics - robespierre - 06-29-2025

(06-19-2025, 08:58 PM)jan-jaap Wrote:  I took the disk out of the drive tower module. Initially it didn't even spin up, but I managed to unstick it by jolting it in the rotational direction of the platters and letting inertia do it's thing. it spins up now, but then it makes a "dakdakdakdakdakdakdakdakdakdakdakdak" noise that it doesn't seem to get out of.

I guess the degaussing has successfully destroyed this hard disk beyond recovery?

You could attach it to a working machine and send a TEST UNIT READY command (this is the SCSI command consisting of six zero bytes {0,0,0,0,0,0}), the status will tell if it is capable of being reformatted.
One way would be to run scsicontrol -Dd /dev/scsi/scXXXXX

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RE: Professional IRIS 4D/50, Clover 1 graphics - jan-jaap - 06-30-2025

(06-29-2025, 02:11 PM)robespierre Wrote:  

(06-19-2025, 08:58 PM)jan-jaap Wrote:  I took the disk out of the drive tower module. Initially it didn't even spin up, but I managed to unstick it by jolting it in the rotational direction of the platters and letting inertia do it's thing. it spins up now, but then it makes a "dakdakdakdakdakdakdakdakdakdakdakdak" noise that it doesn't seem to get out of.

I guess the degaussing has successfully destroyed this hard disk beyond recovery?

You could attach it to a working machine and send a TEST UNIT READY command (this is the SCSI command consisting of six zero bytes {0,0,0,0,0,0}), the status will tell if it is capable of being reformatted.
One way would be to run scsicontrol -Dd /dev/scsi/scXXXXX

I gave this a try, but the doesn't show up anywhere on the bus. I know being a system disk it is jumpered for ID #1. No clever tricks on the Professional IRIS: it's set on the device.

• In an Octane, using a CR-ROM enclosure to power and connect the disk to the system, it doesn't show up in 'hinv' and no device is created under /dev/scsi
  
• I attached the same assembly to a Linux PC with an Adaptec 2940UW card and it doesn't probe a device either
  
• Finally, to rule out the possibility that the CD-ROM enclosure doesn't supply enough power, or that the ultra-wide SCSI buses might not like this very early SCSI disk, I mounted it in a 4D disk bracket and tried with the Crimson. Again, it doesn't show in 'hinv'. IRIX 6.2 has static enties under /dev/scsi for every possible device, but an attempt to open (1,1) with scsicontrol resulted in a 'can't open'.
  

All I can say is that the endless clattering of the head momentarily stops when the SCSI bus is probed by the host, at boot or reboot

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RE: Professional IRIS 4D/50, Clover 1 graphics - jan-jaap - 07-09-2025

I got a bit further with the system, and it's giving me problems everywhere.

Initially, things looked like a quick restoration. There was very little dirt and grim in the system. This corresponds with the story of the original owner, that it had been used for 3 years between '88 and '91 and then sat untouched in a basement for nearly 35 years.

I removed and refurbished the power supply. Again, very clean inside, no leaking capacitors anywhere, just a cracked RIFA safety cap. I replaced it and several output capacitors and it should be good for years to come. Tested under load, voltages good, regulation good. Reinstalled PSU, powered up chassis without any cards in the card cage and verified that fans etc all worked.

I then put the IP4 CPU board back in the system, hooked up a console on the first port and was greeted by:

This seemed like a good moment to clean the memory SIMMs and sockets. But that didn't improve things.

I put in the IP4 board from my existing 4D/70 GT and it booted up without any issue. Both IP4 boards are part# 030-0011-001 rev J, even though one is 8MHz and the other 12.5MHz.

The "new" (misbehaving) IP4 has really old PROM firmware, version 4D1-2.1 from November '87. My existing IP4 had version 4D1-3.1 and I had the feeling it's a little more verbose at startup so I switched PROM chips between the IP4 boards. I verified that my old IP4 boots fine with this firmware. It's quite primitive: there familiar [1] ... [5] menu is missing, it drops you straight into a prompt. And it doesn't know 'hinv':


The new IP4 with the 4D1-3.1 firmware now gives me:


Now, I'm somewhat familiar with early boot code on the MIPS. The real thing on the IP4 is very much like "See MIPS Run" explains, and what it says in the console output:

• It starts executing from the start address with cache disabled and hard coded boot exception handlers in place
  
• Initially it executes in registers only, it initializes some CPU config registers and opens a console UART
  
• It then performs a walking zeros bit test on address A0000000, followed by a walking ones test
  
• Much later, after main memory has been sized and initialized, caches are configured and enabled
  

This thing literally fails the first write access to memory: it writes 0xFFFFFFFE to 0xA0000000 as part of the first walking zero test, and reads back 0. 

The address 0xBFC01ED8 is in the walking bit code. CAUSE register 0x281C decodes as exception code 7, data bus error. The STATUS register value 0x00480000 means BEV (boot exceptions) and CM (would have hit cache if only it has been enabled) so no clue there either.

At thing point I hit the IP4 board with pure alcohol and Deoxit to make really sure the SIMM sockets are clean (visually everything looks good), and replaced the SIMMs with known good ones. No change.

Now, between both Professional IRISes I have three IP4 boards, one 12.5MHz and two 8MHz. I can deal with a dead IP4 later and I put the known-good 12.5MHz IP4 in, and the Clover1 graphics boards. But my misery isn't over just yet:


There's nothing on the attached monitor. A good keyboard and mouse were attached.

Where do I even begin to debug Clover1 graphics? One the GT / GTX / VGX you've got a diagnostics UART on the GM board. No such thing here. No UART chips on the GF3 board. There may be something on the blue IDC connector but then't it's TTL and AFAIK entirely undocumented. I know schematics for IRIS 3130 graphics exist on Bitsavers, but I don't see how they could help me.

   
The LEDs are solid red, unlike the heartbeat pattern on the IP4

Summarizing, it looks like the entire contents of the card cage is fried. Visually it all looks good, clean, no burnt parts, it smells like it's been sitting for 30 years when you power it on, but nothing is smoking or smelling like fire. And the PSU is certainly capable of starting a fire if something shorts. The GE chips on the GF3 get warm to the touch if you let it run for a bit.

There's one thing that worries me a bit and that's the story of the original user about how the entire system had been degaussed when it was decommisioned. Normally you degauss magnetic media like disks and tapes, not an entire 60x70x70cm computer system with a metal chassis. Commercially available degaussers can handle maybe 20x30x30cm volume -- what you need for disks and tapes, but you can't exactly put a deskside computer in one. I wonder if this system was perhaps hit with something else, like an EMP. But then again, if you willingly destroy it, why not trash it afterwards?

Anybody have any good ideas how to proceed, especially with the graphics? I can try to attach a disk and load IRIX 4.0.1 for which I have a matching Diagnostics tape that probably includes diagnostics for the Clover boards. But I have the feeling it's just going to tell me it's dead.

I'm not completely out of ideas with the dead IP4 even if to my knowledge no schematics exist. Its got to be the CPU itself or some of the TTL logic between it and the SIMM sockets. First of all, I have a known-good 8MHz IP4. I can try to swap CPU chips, attach a logic analyzer or scope etc. But it's not my most urgent problem and if this thing was zapped that's not going to be the end of it.

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RE: Professional IRIS 4D/50, Clover 1 graphics - jan-jaap - 07-09-2025

NB: regarding swapping the CPU: I realized later that everything is memory mapped in these systems. If the CPU can fetch code from ROM, and write to the UART, then it's data and address bus are probably not dead. It's more likely that address decoding for the RAM is faulty. I don't know if RAM refresh runs off the CPU clock, that might be worth checking out too

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RE: Professional IRIS 4D/50, Clover 1 graphics - robespierre - 07-10-2025

Even without a schematic of the GF3, you can scope the clock pin of the MC68020 and the address pins, which will tell if it is running or halted.

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RE: Professional IRIS 4D/50, Clover 1 graphics - robespierre - 07-10-2025

If you really wanted to degauss a deskside computer, in theory you could use a handheld degaussing wand. They are designed to remove magnetization from magnetic tape recorders and drives, to avoid corrupting tapes played back or recorded on those drives. So their purpose is opposite to large degaussing tables: it's for data preservation rather than data destruction. I have no idea what effect such a wand would have on a hard disk drive, but it would obviously be hazardous to the data and also the servo patterns.

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RE: Professional IRIS 4D/50, Clover 1 graphics - jan-jaap - 07-18-2025

This 4D/50 'G' keeps fighting me every step of the way. By now the entire system is more or less back together. The PSU is stable, I replaced the dead system disk with a more or less period correct 300MB full height brick that tested good. The tape drive is unusable (capstan turned liquid). The graphics have left the chat it seems and there's no ethernet. I thought I'd cheat it by installing a known good IP4 and booting it off a harddisk with an IRIX 4.01 image dd-ed to it, but it refuses to acknowledge the disk is even there. Of course the 4D1-2.1 PROM doesn't even know the hinv command but while the 4D1-3.1 PROM does, it doesn't show any SCSI devices.

Basically the IP4 I borrowed from my other Professional IRIS takes power from the backplane and talks on serial and nothing else shows any signs of life. I'm starting to suspect the backplane. And about that backplane: these things are very sensitive to correct jumpering of the IACK/BG jumpers. Without it you get interrupt problems which means system crashes. I had a similar problem when I got my first Professional IRIS (See here and down), but that one had clearly been tampered with and then discarded to rot in a warehouse. This one looked pristine and untouched. Still, the IACK and BG jumpers of slot #9 are missing which means a card must be installed there. But there wasn't one, the graphics were in 10, 11 and 12. This can't work...

   

It should have detected the graphics with or without IACK/BG jumpers though. It probes graphics by looking for a magic value at a certain address in memory.

I think I may need to tackle this the other way around: start moving bits of the 'new' Professional IRIS 4D/50 into my existing 4D/70 to test them individually. Who knows, maybe the 'G' graphics work after all

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RE: Professional IRIS 4D/50, Clover 1 graphics - robespierre - 07-18-2025

I think that the GF3 is the only part of the graphics that uses the VME bus. The other boards communicate over private channels with the GF3: via the P2 and P3 backplane connectors and the paddle card that bridges the boards. So the grant jumpers on slots 10,11,12 may be correctly installed.

I have some photos of my 4D/70G when it was working, I will try to dig them up. There may be a shot of the backplane, although I was not too concerned with it at the time.

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RE: Professional IRIS 4D/50, Clover 1 graphics - jan-jaap - 07-19-2025

It's alive!

So the problem was (1) the original 8MHz IP4 appears to be dead, and (2) the VME insertion handles of my 12MHz IP4 are broken. It simply didn't make proper contact with the backplane...

I found back my spare 8MHz IP4 and she's alive

   

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RE: Professional IRIS 4D/50, Clover 1 graphics - robespierre - 07-19-2025

Wow, congrats!
I think I saw replacement card ejectors once, but I'm unsure now where it was. Maybe they were made by Vector (a maker of prototype and extender cards)?
There was also some discussion that insertion of VME cards should become easier if the connectors are treated with DeOxit G100.

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