How to lose most of an an entire collection in one shot

[Rik Bos]

> -----Oorspronkelijk bericht-----
> Van: cctalk-bounces at classiccmp.org 
> [mailto:cctalk-bounces at classiccmp.org] Namens Tony Duell
> Verzonden: zondag 21 juni 2009 22:30
> Aan: cctalk at classiccmp.org
> Onderwerp: Re: How to lose most of an an entire collection in one shot
> 
> > 
> > I really like the 125 for several reasons.  First, it has an HPIB
> 
> I wonder why you like the HP125 and not the HP120, given that 
> they're almost the same machine electronically. All the 
> points you make apply to the 120 as well.
> 
> > interface for disks, etc.   That interface also allowed it to be a 
> > controller for calibration instruments.  It also used an easy to 
> > create
> 
> Sure, but most HP machines have HPIB :-). The HP120 doesn't 
> properly support the HPIB port in the BIOS (IIRC there's no 
> BIOS function to read from an HPIB device) so you pretty much 
> have to talk to the 9914 directly. Not a big problem, but if 
> you get it into the wrong state you may find you can no 
> longer talk to the disk drives. 
> 
> For talking to instruments, I prefer to use an HP9000/200 
> machine with a second HPIB port (HP98624). Firstly there's 
> much better standard software support for the HPIB interface, 
> and secondly, if one of the instruments 'hangs the bus' 
> (likely in my case as I might well be repairing said 
> instrument), I can still talk to the disks.
> 
> > disk format.  Also handy.
> > 
> > 
> > > When I said I didn't like the design of the HP120, I 
> didn't mean the 
> > > 'looks ' of the machine. I meant the electronic design -- 
> a separate 
> > > terminal processor communicating with the application processor 
> > > through a little 'mailbox' and a very strange video circuit.
> > >   
> > 
> > I worked for two companies which made terminal / PC combo 
> devices.  I 
> > suppose I have a weakness for them.  The 125 behaved as a decent 
> > terminal on an HP 3000, and ran as a CP/M computer simultaneously, 
> > allowing a switch between disparate processes that the standard PC 
> > world wouldn't see for many years.  The "strange" circuitry made it 
> > easy for the user to alternate processes, and allowed communication 
> > between
> 
> It's not so much that, but rather the actual design of the 
> video circuit. 
> It uses that National 8350 chip (actually a differently 
> mask-programmed one for a different screen format). That's a 
> strange chip, it interrupts the Z80 at the start of each 
> character line, and fills an 80 byte shift register with characters. 
> 
> And then there's the attributesm which are set on a character 
> line basis. 
> Basically, every character is either normal or enhanced 
> (decided by bit 7 of the chracter code). You can only have 
> one type of enhancement in a given line. So you could have 
> normal and underlined characters in the same line, but you 
> can't have normal, inverse, and underlined characters all in 
> the same line.
> 
> Another problem is that AFAIK there's no official way for a 
> CP/M program to set the parameters of the serial ports (not 
> even the 'printer' port). 
> The serial chips are on the terminal processor bus, there's 
> no direct way for the application processor to talk to them. 
> There's an undocumented way to run code on the terminal 
> processor (in that at least one HP application does that), 
> but I can't find out how to do it.
>  
> > them.  It's appropriate to have complex hardware and 
> software to make 
> > the use of the machine easier.  At least, that's my theory.  The HP 
> > 125
> 
> Sure, but I don't think the HP120 falls into that category. 
>  
> > was both pretty and easy to use, as an HPIB controller, an HP 
> > terminal, and as a CP/M machine.
> 
> I'd much rather have an HP9000/200....
> 
> -tony
> 
Me too, and for the speed a HP 9000/300 ;-)
I like the view of a HP 125 ET-head but it is not a very handy machine.
The 9000's series 200 or 300 are much more useful.

Rik