[Simh] CI750 tech docs and VAX firmware

[Tim Stark]

Hmm, interesting.  K.scsi is not mentioned in my HSC50/70 docs.  Does anyone have any docs contains K.scsi tech info?

Thanks again,
Tim

-----Original Message-----
From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Johnny Billquist
Sent: Monday, March 6, 2017 6:47 PM
To: simh at trailing-edge.com
Subject: Re: [Simh] CI750 tech docs and VAX firmware

On 2017-03-06 15:03, Timothe Litt wrote:
> There were also HSC40 & hsc60.

Right. Pretty similar to all the others. The differences (as far as I can remember) were mostly on the number of SDI/STI ports available, and the amount of cache in the machine.

> The differences in the hsc family members were the processor, cache, 
> load device, number of channels, and maximum number of ports.  Some 
> models were field-upgradable.  Also, later models supported
> (reluctantly) the K.scsi module, which allowed the HSC to serve SCSI 
> disks and tapes.  (SCSI was carefully analyzed & found to have 
> reliability/data integrity issues; DEC's answer was DSSI.  Rather like 
> Beta & VHS - "good enough, but cheaper" won.)

Right. However, to use the K.scsi, you actually needed to upgrade. The
HSC90 with the capability to use K.scsi was the HSC95. I don't think the
HSC70 could at all. The 40 and 60 could, I think, but I wonder if they then were renamed 45 and 65. I think I still have some documentation somewhere, but it would take some digging to find this.

> At some point, support for 18-bit disks (576 byte sectors) was dropped.
> The HSC50 definitely had it; the HSC90 did not.  I'm unsure about the HSC70.

Unless I remember totally wrong, only the HSC50 could do 576 byte sectors. It was dropped in a pretty early version of CRONIC, before support for any other HSC controller existed.

	Johnny