Jim Brain brain at jbrain.com
Tue Dec 30 17:35:09 CST 2008

Tony Duell wrote:
> The HP drives work at a much lower level. The file system is managed by 
> the host computer. The commands to the disk drive unit read/write bocks 
> (essentially the same thign as sectors). It's up to the host to turn 
> those into a file system.
This is not as problematic as it may seem.  The uIEC can auto-update the 
firmware, so I could simply write a special version of the SW for 
HPIG/GPIB (even different flavors for the various command sets) and the 
owner can simply place the flavor desired onto a flash drive, turn on 
the unit, and it will program itself with the correct DOS.

> You could probaly find an HP150 or an HP9000/200 machine fairly easily 
> on E-bay. 
I am hopeful someone finds enough value in the possibility to provide a 
unit for testing.  Still, this is very premature, since I still need to 
get the PET IEEE stuff working.
> Now I don;'t know the exact details, but I read (I think on one of the 
> HP9845 pages) that somebody had written an HP drive simulator programs 
> for PCs fitted with an HPIB card (I believe said program has source 
> available if you want to look for hints on the command set, etc). But one 
> thing that this weg page siad was that it couldn't run with a 9914-based 
> HPIB card, since HP did something that was essentially against the 
> standard and which the 9914 couldn';t do. I do know that HP used the 9914 
> in their computers quite a bit, but that the drives used the Intel 8291. 
> Of course if you're planning on bit-banging the HPIB protocol on the pins 
> of a microcontroller (I think you need a little external logic, there is 
> one transition where you can't take arbitrarily long to change one of the 
> signals), then this won;'t be a problem.
It'll be a bit-bang approach, so save HW costs, but I can wire up some 
TTL logic if needed.


More information about the cctalk mailing list