[vcf-midatlantic] Found: VMS Hobbyist CDs

Jameel Akari jakari at bithose.com
Tue Jun 6 16:35:10 EDT 2017

On Tue, 6 Jun 2017, Dave Wade via vcf-midatlantic wrote:

> The CDs can be ripped an written on a normal drive, so that makes sense.
> Dave

Yeah, I went through this recently-ish with IRIX CDs.  (They're EFS 
filesystem images, not ISO-9660, and the bootloader doesn't handle 2k 
blocks in that context.  Meanwhile, the drives I have that can do this 
512-byte thing are old enough that burned CDs are iffy.)

Thank you, Neil, for dumping the CD and posting it, even it wasn't in 
proper .dogfood or whatever "format." :)


> On 6 Jun 2017 20:05, "Jonathan Gevaryahu via vcf-midatlantic" <
> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>> AFAIK OSes which require drives with '512 byte blocks' is sort of a scsi
>> hack.
>> The physical data on the cd surface is 2048 byte blocks (plus ECC and
>> subchannel data you don't normally see for 2532 bytes per sector, plus
>> headers and sync marks etc)
>> The whole 512 byte thing is a special mode certain cd drives have which
>> sends each 2048 byte block to the host computer as if it was four separate
>> 512 byte blocks/sectors, but its really just a translation layer. Not all
>> drives do it.
>> The actual CD contents for these VMS cds are 2048 byte blocks, the 512
>> byte magic happens in the drive, AFAIK.
>> I could be wrong about this.
>> On 6/5/2017 12:48 PM, Brian Schenkenberger via vcf-midatlantic wrote:
>>> Neil Cherry via vcf-midatlantic writes:
>>> On 06/03/2017 11:21 PM, Jim Scheef wrote: > Neil, > Could you pull ISOs
>>>> of a couple of the CDs before you take them to IA? > Jim
>>>> I'm using my Linux box to see if I can copy the entire CD to an image. I
>>>> don't know how well this will work but it won't take much space.
>>> http://tmesis.net/OpenVMS_Hobbyist/
>> --
>> Jonathan Gevaryahu
>> jgevaryahu at gmail.com
>> jgevaryahu at hotmail.com

Jameel Akari

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