David, Thanks for your detailed report. I appreciate all the work that you are doing for VCF! On Fri, Feb 7, 2020 at 10:20 PM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
Executive summary: I checked out the two 3B1's in the museum. One had hardware mods to allow more and larger disks and is functional though the drive doesn't want to reliably spin up. The second has a motherboard fault. I also updated the image on the 3B1 in the Museum and added a USB cable hidden behind the center expansion board cover to allow easier updates to the disk image. Due to the rain and the filler work running long the Xerox 8010 didn't get that much work done. It appears to have a hardware fault though was running some. Fault may just be with the control panel. The hard drive wouldn't spin properly, likely loose belt. The second Xerox was not investigated at all.
TLDR:
The plan was to mostly work on the Xerox 8010 Star/Dandelion but we decided to not try to move it in the heavy rains Saturday so I did more 3B1 work. I checked out the two 3B1's in the warehouse and removed the batteries from both.
The first one with sticker NCR SN 02233914 on the side was interesting. The motherboard had been modifed to the P5.1 motherboard configuration. This change was under development when AT&T killed the UNIX PC line. The last software supported it but the updated motherboard was not shipped. P5.1 increases the number of heads supported from 8 to 16. The hard disk controller chip was also changed to the WD2010 which allows the number of cylinders to be increased from 1024. The chip supports 2048 but the operating system limit is 1400. It also had the modification to support a second hard drive. You can see the grill for one of the fans had been cut down to allow the cables for the second drive to exit the case for an external drive at some point. The fan was reinstalled and no cables are present for the external drive. Currently it is configured with a single DEC RD54 hard drive. The drive capacity is 152 MB vs the standard configuration of 67 MB. I removed the RD54 to backup with my reader. It initially didn't want to spin up but with some light hits to spin it around the spindle axes it spun up and I was able to read the drive. The MSB for the head was put in the sector number byte since the WD2010 only supports 8 heads. I hadn't run across a machine with the P5.1 mods so had to fix my 3B1 decoding to match. The drive label had 42 defects listed. I found 7 sectors with read errors, the first 5 matching sectors in the defect list. The machine has 2 MB on the motherboard and a 2 MB memory expansion board so has the maximum amount of memory supported. It also has a floppy tape drive expansion board and cable with it. I forgot to dig around on the shelf rack to see if the drive was around. May be good to see if the drive is around so it can be kept together with the computer. This machine had the battery holder installed. I removed the BR2325 battery. You likely can install a BR2330 to get a little longer life. BR2330 is the battery I have in the museum 3B1. After I put everything back together the computer was running but the hard drive wasn't spinning up. Likely the drive is unhappy. I didn't open it back up to check that I got the power plug fully seated. I also did not test the floppy drive. This machine is more tricked out than the one in the museum except for not having the DOS expansion board. I haven't looked that much at the disk image. It does have some things I haven't seem before, a CAD program and an office suite Smart Software System with wordprocessor, database, spreadsheet, and spellchecker. It had noticable usage by one user and a couple other accounts.
A few pictures here http://www.pdp8online.com/3b1/vcf-p5.1/pics.shtml
The second 3B1 is labeled 370429065 on the bottom. I was able to read the drive but it had 50 bad sectors and got worse with further read attempts. The drive didn't sound too bad. It's possible that the drive is useable with a reformat. The system files were similar to the previous machine and it only had one user account with no significant content so I didn't try harder to recover the bad sectors. This machine does not complete its power on diagnostics. It has one green LED lit which indicates that the video ram failed its test. I did not try to fix the fault. This machine still had the soldered in battery so I cut it out. It was a CR2430. It has a dual serial port expansion board installed without memory installed so only has the 2 MB on the motherboard.
I opened the museum 3B1 and ran a USB cable from the emulator with the end tucked above the center expansion slot memory board. It can be accessed by removing the center slot cover. It is a USB-C connector. I updated the image with some more demo software. Some of the additions are it has BASIC, Logo, gcc, Microsoft Word & Multiplan, simple hello world in C, BASIC, and Logo, a ~10 line Logo program which draws a tree and the software to use the DOS coprocessor board. I need to write up a description of how to use the stuff installed. I demoed at the workday.
Connor was working on a VAX which didn't want to boot. We used my mfm board to verify that the RD54 drive wasn't going ready. Comparing to the 3B1 RD54 it sounded like the heads were stuck. He opened the drive and it had a deteriorating rubber stop for the heads that was likely preventing them from moving. It was a blue rubber ring on the bottom plate of the drive and reasonably accessible. He removed as much of it as he could and the heads properly went through the startup sequence. I tried to read the drive with my mfm board and it had an excessive number of read errors to be useful. I did verify it was a VMS disk. It appears to have the problem commonly seen where the head stack is out of alignment. Some of the heads are so far out of alignment you read the data from the next cylinder. Drive may be recoverable with methods like this. http://www.pdp8online.com/mfm/head_servo/ Connor pulled 2 more RD54's from warehouse machines to try to get a good image for the emulator in case we can't get one formatted by the VAX. One drive wouldn't work, I think stuck heads again. The other was readable. It was from a PDP-11, possibly a 73. It is RT-11 with KASTLE SYSTEMS building monitoring software.
Only a few hours were left when I got to the Xerox 8010. I pulled the boards and power to the hard drive and verified the power supply voltages were within specification. I also inspected for anything suspicious. For some reason the floppy drive power and data cables were disconnected. I released the spindle and head shipping locks on the hard drive and verified the spindle would turn. I hooked up my mfm board and tried to read the drive. The drive barely spun. I think the belt is slipping. I didn't have time to remove the drive from the machine to work on further. We installed the cards and powered on the machine after Connor found the power button hiding behind a cover. As previously reported the diagnostic display counted from 0 to 10 repeatedly. If I understand the documentation, the machine is supposed to cycle through these codes when the alt boot button is pressed and you release it when the code matches the operation you wish to perform. I played with the button but it still always went though the 0-10 sequence. It is reading the button as always depressed. The reset button next to it did function. The hard drive power is currently disabled and the shipping locks installed. The floppy power and data cables were reconnected. The machine is missing its castors. They need to be replaced. It still needs cleaning. The one I was working on one of the side panels is broken at the bootom. I think the other machine had a good side panel. Their is some rust but the machine looks in reasonable condition. I did not do any testing on the second machine.
-- ========================================= Jeff Brace Vice President & Board Member, VCF East Showrunner Vintage Computer Federation http://www.vcfed.org/ jeffrey@vcfed.org