Removable storage on VaxStation 3100 model 38?

[jplr]

Hi all,

I guess any Floppy/CDROM on a VaxStation 3100 model 38 would have to use Centronics CN-50 SCSI interface?
On ebay a SCSI floppy drive costs more than my VaxStation, is there some means to use a PC floppy disk (Shugart Associates SA400 FDD interface) through some SCSI CN-50 => Shugart converter? Is there such a thing?

As I am lazy: There are two internal SCSI CN-50 in my machine, one seems to have been used (cartridge reader?) but what was the common use for the other?
Is there some order, for example, does some device must be connected preferably to one of these two connectors?

Thanks!

Jean-Pierre

 

[g4ugm]

OK so the SCSI floppies I have seen, were, on investigation, normal floppies with a SCSI adaptor board. Look at this one on E-Bay

TEAC FD-235HS FC-1 SCSI Floppy Drive | eBay

For sale is a very rare SCSI floppy drive from my collection.

www.ebay.com

See there is a second board underneath. I have had a coupe of these, one in a SUN tower and the other in a VaxStation. Both the same.

The model 30 is limited to a 1gb boot disk so there were probably multiple hard drives and a CD, Floppy or SCSI tape. The user manual is here:-

http://www.vaxhaven.com/images/0/00/EK-VSM31-OM-002.pdf

Which explains some of the options. Hope this is helpfull...

 

[Wildfire]

Hi all,

I guess any Floppy/CDROM on a VaxStation 3100 model 38 would have to use Centronics CN-50 SCSI interface?
On ebay a SCSI floppy drive costs more than my VaxStation, is there some means to use a PC floppy disk (Shugart Associates SA400 FDD interface) through some SCSI CN-50 => Shugart converter? Is there such a thing?

As I am lazy: There are two internal SCSI CN-50 in my machine, one seems to have been used (cartridge reader?) but what was the common use for the other?
Is there some order, for example, does some device must be connected preferably to one of these two connectors?

Thanks!

Jean-Pierre

Hello Jean-Pierre,

all Floppy/CDrom drives who have SCSI should run, the CDrom needs to be jumpered to block-size 512.
If i remember it correctly the external SCSI connector on the 38 is an inverted one, so the box has male and the cable must have female connectors.
If you don't have it you need an original or 3rd party cable for the external SCSI, as an alternative if you are able to make yourself an adapter with female-female
you can use normal SCSI cables from that adapter on...
The 38 has two SCSI buses, the extermal port should be bus b.

https://web-docs.gsi.de/~kraemer/COLLECTION/DEC/vs3kc.insidedisk.jpg

Your system should look identically, the blue flat cable is normally used for the SCSI floppy -- i assume that also another harddrive would also fit without problems...

The only other thing to have an eye on is the right SCSI id order bc of booting/tape/cdrom and so on, should be readable in the manual...

 

[Wildfire]

OK so the SCSI floppies I have seen, were, on investigation, normal floppies with a SCSI adaptor board. Look at this one on E-Bay

TEAC FD-235HS FC-1 SCSI Floppy Drive | eBay

For sale is a very rare SCSI floppy drive from my collection.

www.ebay.com

You are absolutely right, DEC took normal floppy drives and designed their own SCSI adapter, but the TEAC ones in the aution seen do also run in the 38, i saw systems of other hobbyists using them.

 

[Wildfire]

The model 30 is limited to a 1gb boot disk

Yes, due to firmware limitations.

But i read that people used bigger disks with f.e. 9gb and used only the first gig and it also ran.

The other possibility is the "Moeller patch", he wrote not only the one used with the VAXstation/MicroVAX 2000 but also a one for the 3100 series...

 

[gslick]

Yes, due to firmware limitations.

But i read that people used bigger disks with f.e. 9gb and used only the first gig and it also ran.

I have a bunch of 9GB SCSI disks. I have used them as boot disks on VAXstation/MicroVAX systems by using sg3_utils sg_format to soft resize them down to 1GB in size (2,097,152 LBAs).

http://sg.danny.cz/sg/sg3_utils.html

For example:

C:\sg3_utils>sg_readcap.exe pd1
Read Capacity results:
Last logical block address=17849999 (0x1105e8f), Number of blocks=17850000
Logical block length=512 bytes
Hence:
Device size: 9139200000 bytes, 8715.82 MiB, 9.1392 GB

C:\sg3_utils>sg_format.exe --count=2097152 --resize --verbose pd1
inquiry cdb: 12 00 00 00 24 00
IBM DDRS-39130D DC1B peripheral_type: disk [0x0]
PROTECT=0
mode sense (10) cdb: 5a 00 01 00 00 00 00 00 fc 00
mode sense (10): pass-through requested 252 bytes but got 28 bytes
Mode Sense (block descriptor) data, prior to changes:
Number of blocks=17850000 [0x1105e90]
Block size=512 [0x200]
mode select (10) cdb: 55 11 00 00 00 00 00 00 1c 00
Resize operation seems to have been successful

C:\sg3_utils>sg_readcap.exe pd1
Read Capacity results:
Last logical block address=2097151 (0x1fffff), Number of blocks=2097152
Logical block length=512 bytes
Hence:
Device size: 1073741824 bytes, 1024 MiB, 1.07374 GB

 

[leegleason]

Yes, due to firmware limitations.

But i read that people used bigger disks with f.e. 9gb and used only the first gig and it also ran.

The other possibility is the "Moeller patch", he wrote not only the one used with the VAXstation/MicroVAX 2000 but also a one for the 3100 series...

For the interested, the Moeller patch for the large disk booting problem is discussed at Moeller 3100 patch message

 

[Wildfire]

For the interested, the Moeller patch for the large disk booting problem is discussed at Moeller 3100 patch message

Thanks !

I totally lost where it is...
Funfact:
Wolfgang had at that time an account on GWDVMS.
This system was an DEC4000/620 with 512MB.
After it's last shutdown it came to the usual recycler companies.
Accidentally i rescued it there and noticed a while later bc of the name written on a sticker where it came from...
I still have it

 

[Wildfire]

I have a bunch of 9GB SCSI disks. I have used them as boot disks on VAXstation/MicroVAX systems by using sg3_utils sg_format to soft resize them down to 1GB in size (2,097,152 LBAs).

http://sg.danny.cz/sg/sg3_utils.html

For example:

C:\sg3_utils>sg_format.exe --count=2097152 --resize --verbose pd1

Hmmm, interesting.
You wrote soft resize, so this is not doing the changes in the firmware directly ?

Years ago i did something similar to some ide/pata drives - setting them from the original 20/40 gig to 1-2 gig.
I used a tool which booted directly from cd and then one has to go through some cryptic menu things and change the settings directly in the drives firmware.

The former sg_utils is a name i heard of some time ago but up to now i did not use it - quite interesting what it can do!
Thanks for the link, now on my list of reading/testing the next weeks

 

[gslick]

Hmmm, interesting.
You wrote soft resize, so this is not doing the changes in the firmware directly ?

What I meant by "soft resize" is that the sg_format utility isn't doing a low level format of the drive using a SCSI FORMAT UNIT request, but I believe it is using a SCSI MODE SELECT request to effectively alter the value that is returned by a SCSI READ CAPACITY request, which used by the host firmware and operating system to determine the size of the drive. This is a non-volatile change that persists across power cycles of the drive. I don't know how that is typically implemented on the drive, maybe there is a private section of the disk that the firmware uses to store various disk parameters.

I'm pretty sure that if the sg_format utility is used to "soft resize" the drive back to the full capacity, the data that was previously hidden above the reduced capacity size is fully visible again as it was before and hasn't been lost, although I don't think I have tried to verify that.