uIEC/SD == AWESOME!
ard at p850ug1.demon.co.uk
Thu Jan 1 17:29:23 CST 2009
> > I don;t know how much firmware space you have, but it would be nice if at
> > least Amigo and SS/80 could be fitted in together with a jumper/switch to
> > select between them. I'd also suggest some kind of configuration
> > switch-thingy to select the drive size -- some HP machines moan if the
> > drive is not the one they're expecting...
> Anything is possible.
... except skiing through a revolving door :-)
More seriously, there must be a limit to the code size.
To goive you some idea as to the complexity, I think the HP Amigo drives
had 8K of ROM, the SS/80 ones that I've worked on had 16K. This is 6809
machine code. The controller board contains a 6809, EPROM, RAM, the HPIB
chip and standard-ish hard and/or floppy controller chips
Obviously if you bit-banged it, it would take a little more code for that
than to talk to the HPIB chips. I don't know how talking to a CF card (or
whatever) compares to talking to a WD2973 floppy controller or a WD1010
hard disk contorller. But that should give you some idea.
> > HO did bti-bang HPIB on several devices. The 82169 (HPIL-HPIB translator)
> > uses an 8049 IIRC, a custom HP buffer chip (which is nothing more than
> > line drivers/receivers) and a couple of TTL chips. The 98034 (HPIB
> > interface for the 98x5 machines) used HP's custom 'nanocontroller', some
> > standard buffer chips (3448s?) and a little TTL. Scheamtics for the
> > latter should eb on the Austalian Museum site.
> I'll check into this (any other links to HPIB interfaces?) Right now,
HPIB == GPIB == IEEE-488 (at least at the hardware level). Alas I don't
think the standard -- IIEE-488-1975 is freely distributable (IMHO
standards _should_ be, but they rarely are). I did read it once -- many
years ago -- but I don't have it. If you can find it, it's somehting you
should read. HPIB disk units tend to use many of the features of the HPIB
Early HPIB instruments tended to do the IEEE handshakes in hardware
(either monostales, or state machines), so that's probably not a lot of
use to you. The conputers tended to use 9914 interface chips, again not a
lot of use. And HP's custom HPIB chip, the 1TL1 (Medusa) is nice, but not
a lot of interest to you.
Commodore almost always bit-banged it, so looking at the schematics of
PETs and their peripherals might be a help.
Otherwise just poke about on the Australian museum.
> I'm fighting with the fact that I believe the full complement of
> IEEE-488 signals is 17, and it sure would be nice if I could get it down
> to 16
Don't worry, it's 16 active signals :
8 data lines
3 handshake lines (DAV, NRFD, NDAC)
5 control lines (ATN, EOI, IFC, SRQ, REN)
And then 7 logic grounds and a shield ground.
All signals are bidirectional (although, unless you intend to be a
controller, you don't ened to be able to drive some of them). Some devices
drive them with totem-poll drivers, others open-collector (with passive
termination). There are arguements in favour of either for particular
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