HP-IB, Amigo/cs80 was Re: hp 9153 floppy & disk

[Tony Duell]

> 
> On Fri, Feb 12, 2010 at 2:15 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> >> So, if I would make the hardware, how many people are interested in a
> >> box which emulates HP-IB, Amigo/cs80 ?
> >
> > I would be very interested provided (a) I can acutally build one (no
> > BGAs, but PQFPs, SOICs, etc are no problem) and (b) it's 'open'. Although
> > I am not much of a programmer, I'd be happy to help out where I can.
> 
> How about an AVR-based box (open, no BGAs, etc) perhaps with an SD
> socket or CF socket, with an HPIB interface that will work with a)

That would seem to be a good idea. 

I would suggest that the HPIB interface be buffered (using either the 
75160/1/2 series of chips, which would use 2 devices, or 4 off 3448 or 
similar.).  As I mentiond a few weeks back it is a lot easier to replace 
a buffer chip than a microcontorller iff something goes wrong).

> "real" IEEE-488 hosts and b) PET/CBM hosts which are electrically
> GPIB/IEEE-488, but might have some "Commodoreisms" when it comes to
> timing and throughput and such since they are implemented as 6502 code
> wiggling PIA and/or VIA I/O lines?

There should be no broblem with 'banging' the handshake on 
microcontroller port lines. HP haev been known to do this. IIRC you need 
a very small maount of external logic (let me check) to ensure one signal 
changes fast enough. It's only a couple of TTL chips, though (and common 
ones, like 74x00), not really worth putting in a PLD.

HPIB would take 16 port lines of the microcontroller + 2 or 3 to control 
the buffer driection. And then you need however many port lines it takes 
to talk to the flash memroy device. 

As regards code size, IIEC, the HP9133H (SS/80 protocol) has 16K of 6809 
conde in it. That should give you some idea as to the complexity.

> 
> Once you have a platform that is electrically and timing-compatible
> with HPs and PETs, it shouldn't matter if you choose to implement
> Amiga/CS80 or CBM "DOS" at the firmware level, and a generic "IEEE
> Disk" would be useful in a number of environments, not just HP and
> CBM.  I wouldn't require that the same box be able to do either
> Amiga/CS80 and CBM DOS without a reflash, but it might not be

The Commodore and HP command sets are very different. The major 
difference is that Commodore drives are file-oriented devices (you open a 
file by name, you can get a directory, etc), while HP devices are block 
oriented (you ask to read a particular block on the disk, the host OD 
reads the appropratie blocks to read the directory, then finds the blocks 
that comprise the file you want, and reads those, etc). Yes, I know the 
Commodore drives let you read disks at hte block level, but most of the 
time you didn't do that. H


-tony