DEC RK07 drive interface specs wanted

From: Peter C. Wallace <>
Date: Thu May 13 09:25:20 2004

On Thu, 13 May 2004, Jochen Kunz wrote:

> On Thu, May 13, 2004 at 11:31:25AM +0200, Fred N. van Kempen wrote:
> > > Hmmm. Replicating the RK611 in an FPGA is an interresting idea. - If you
> > > can get complete shematics and there are no funky things like an AMD bit
> > > slice CPU in it.
> > Nope, just logic.
> The RK611, but not a UDA50 or anything else that is "smart".
> When I go through the work of designing a UniBus board, I would put
> enough on it to run NetBSD on the controller. The UniBus attachment
> should be implemented in a FPGA to have maximum flexibility in the
> hardware. Software on top of this should be a NetBSD kernel driver,
> perhaps with a userland daemon to support the kernel driver and control
> it. It would be possible to emulate any UniBus device, including a
> PDP-11, VAX, PDP-10, ... CPU. Unfortunately I don't have the experience
> nor the resources to build a board like this.
> "Hey, I can telnet / slogin to the disk controler of my PDP-11!"
> That would be expensive, but you can do _anything_ with it. So you can
> use the board for a wide range of applications, resulting in higher
> production volume and lower cost. I know that a list member was
> designing a board like this. I don't know how far he got. But my offer
> is still valid: Give me hardware and I'll care about the NetBSD port.

Thats a dangerous offer...

I may not be that expensive nowadays. A MIPS or ARM SOC with PCI for I/O
expansion and Built in Ethernet, SDRAM support and simple I/O bus are
available for between $15 and $30. The bus interface FPGA is really simple and
probably in the $10-15 region. PCI is nice as it makes it easy to add MiniPCI
slot for wireless, USB, IDE, SCSI etc. CPUs without PCI are even cheaper.

> > The Unibus transceivers is indeed an issue- we dont have heaps of
> > those laying around. On the other hand, their exact function and
> > specs are known (see the Peripherals handbook, 1972-ish or so),
> > and we should be able to re-implement them in discrete logic,
> > or bite the bullet and do a pin-compatible replacement, and
> > have 1,000 made.
> A re-implementation in discrete logic was my thought too. Depending how
> it fits it may be possible to build a UniBus / QBus combi-board that
> could be used in both busses depending on jumper settings.
> --

Discrete mosfets with RC at the gates (say sot23 if surface mount) would give
you all the drive you needed without excessive edge rates. The input side
could be done with Schmitt trigger CMOS parts or even quad comparators if you
wanted to get fancy about input threshold...

> tschüß,
> Jochen
> Homepage:

Peter Wallace
Mesa Electronics
Received on Thu May 13 2004 - 09:25:20 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:10 BST