Rear Admiral goods received (upgrade for the Lt. Kernal)

[maraud]

Wow.  The impression I got from your post was that the Rear Admiral was for existing Lt. Kernal units.  I had no idea this would translate into ACTUAL Lt. Kernal II units being sold. 

http://cgi.ebay.com/XETEC-LT-KERNAL-II-160MB-HARD-DRIVE-COMMODORE-128-NEW-/300486908771?pt=LH_DefaultDomain_0&hash=item45f66a5b63

Thinking about brand new Commodore hard drive systems being sold in 2010 makes me smile.  I hope he sells lots of units.

Nice... I remember the extreme negativity and skepticism when word of the Rear Admiral first came out. It is nice to see that indeed an actual product followed. I'm doubtful I'll ever get one as it seems to not be compatible with the SuperCPU 128. Still, nice to see new product on the market.

I'm not sure this is true.  I do know of a Centipede BBS run by DEADMAN, which I know is running an RA unit, and I believe is using a SCPU128.

[RobertB]

...which I know is running an RA unit, and I believe is using a SCPU128.

How do the SuperCPU 128's MMU adapter and the Rear Admiral's MMU adapter coexist with each other?

          I thought it was one or the other,
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug
          The Other Group of Amigoids
          http://www.calweb.com/~rabel1/
          Southern California Commodore & Amiga Network
          http://www.sccaners.org

[RobertB]

     Over at retro-link.com/smf , I've posted a more complete, summary description of the Rear Admiral, thanks to various postings at Lemon64.  Go to

     http://retro-link.com/smf/index.php?topic=542.msg2172#msg2172

          Truly,
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug
          The Other Group of Amigoids
          http://www.calweb.com/~rabel1/
          Southern California Commodore & Amiga Network
          http://www.sccaners.org

[RobertB]

Here's what I received in the package -- the Rear Admiral DOS v7.3 disk (improved over the original LtK DOS)...

On comp.sys.cbm, Steve, who has the complete Rear Admiral system, says that MyTec Electronics installed a larger capacity mechanism (1.2 gig) in preparation for RA DOS 7.4.  Getting rid of the limitation of 320 megs which the original Lt. Kernal DOS and the RA DOS 7.3 have, the future RA DOS should have 100 LU's and a capacity of 1GB.

          Truly,
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug
          The Other Group of Amigoids
          http://www.calweb.com/~rabel1/
          Southern California Commodore & Amiga Network
          http://www.sccaners.org

[BigDumbDinosaur]

Here's what I received in the package -- the Rear Admiral DOS v7.3 disk (improved over the original LtK DOS)...

On comp.sys.cbm, Steve, who has the complete Rear Admiral system, says that MyTec Electronics installed a larger capacity mechanism (1.2 gig) in preparation for RA DOS 7.4.  Getting rid of the limitation of 320 megs which the original Lt. Kernal DOS and the RA DOS 7.3 have, the future RA DOS should have 100 LU's and a capacity of 1GB.

That would entail a significant rewrite of the LK DOS, as the 11 LU limit is somewhat cast in concrete.  The LU parameters are maintained in a fixed sized table on SCSI device zero, said information being loaded into the host adapter shadow RAM at boot-time.  The table would have to be expanded ten-fold to accommodate 100 LUs, with a corresponding increase in shadow RAM consumption.  This is not to imply that it can't be done, only that it won't be trivial.

I've always felt that the designation of LU 10 as the DOS LU was a design error, as it needlessly encumbered the ability to expand the system.  Had the DOS LU been 2 instead of 10, with user-defined LUs extending from 3 onward, the expansion of the system would have been less painful.  Oh well, that's water under the bridge.  After all, we're talking about a system whose production ceased nearly 20 years ago.

Incidentally, the 1 GB limit has to do with the use of the SCSI-1 protocol to talk to the drive.  SCSI-1 uses 21 bit LBAs, which can address a maximum of 2,097,152 disk blocks, or 1,048,576 KB.  Back when the Lt. Kernal was designed, a 20 MB disk was huge.  It would take a significant hardware revision to the host adapter to allow the use of SCSI-2 and its ability to address the disk with 32 bit LBAs.