D9090 (was Re: VIC-1001 ROM sighting)

From: Ethan Dicks (ethan_dicks_at_yahoo.com)
Date: 2001-09-17 23:42:16

--- Daniele Gratteri <daniele_gratteri@inwind.it> wrote:
> ----- Original Message -----
> From: "Ethan Dicks" <ethan_dicks@yahoo.com>
> To: <cbm-hackers@cling.gu.se>
> Sent: Monday, September 17, 2001 4:07 PM
> Subject: Re: VIC-1001 ROM sighting
> > I don't know how anyone else does it, but I got an IEEE-488 cart and
> > plugged in a D9090.  Not widely available, but if it works on a BASIC2
> > PET, it'll work on a VIC-20 or anything else out there.
> I didn't think about this solution, effectively. I didn't remember the
> existence of that cart.

It's a simple one - four chips - two IEEE line drivers (TI 75xxx series),
a VLSI I/O chip (6522, ISTR) and a ROM.  I remember reverse engineering
it when I got it years and years ago, and I think there's a little extra
work involved in twiddling the I/O lines compared to the original CBM GPIB
design, but it should be *about* the same speed - 4Kb/sec IIRC.

> You are lucky to own a D9090! I think it is a good piece of hardware.

Luck had little to do with it.  I picked up a few broken drives years ago
for hundreds of dollars.  Between sending HDAs out for repair ($70 each!)
and a little minor troubleshooting, I got stuff working.

The good news is that between Germany, Australia and the States, there's
renewed interest in them.  We've cleared up some naming issues with the
ROM files, and have a good start on delving into the internals.  My goal
is to be able to use something other than a 5Mb or 7.5Mb ancient MFM drive
inside.  It is possible to use a larger drive, but only at the capacities
it's expecting (i.e., it ignores heads over 6 and cyls over 153).  Eventually,
we should be able to patch the ROMs for other drives, up to the limit of
the filesystem (probably 255 cyls).

Stay tuned to the D9090 directory on funet as interesting things worth
downloading appear.


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