DEC RK07 drive interface specs wanted

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Thu May 13 16:34:22 2004

> The real question is: What is more time consuming? Rebuild the RK07 or
> build a solid state RK07 replacement.

It also depends on what you want to do. To me, a classic computer system
is more than just the CPU. The peripherals are part of it as well.
Running a PDP11 with flash memory mass storage is not the same as running
one with a demountable hard disk.

> > Wouldn't it be simpler to make a Unibus card with the flash memory and
> > interface on it that pretended to be a disk controller?=20
> I don't know. I suspect that I would need a FPGA for bus glue logic and

DEC managed with a handful of TTL. You don't _need_ an FPGA. You'd want
to do DMA, which means that your device has to source the bus address,
but that's not hard (a counter + buffers, basically). You also need the
word count register (another counter), and some glue logic. Not that hard
to build.

> maybe a microcontroller a bit more powerfull then a 8 bit Atmel AVR.
> This seems to be more complex then a solid state RK07 replacement. A
> RK07 replacement should be doable with a hand full of serial <=3D>
> parallel converter chips (data and controll words are transfered
> serially between drive and controler), a 8 bit Atmel AVR and a FLASH,
> IDE, whatever disk.

One big difference is that the RK07 interface speed is determined by the
conotroller, and your device has to keep up, keep on squirting out the
bitstream at the right rate. The Unibus can be run as slow as you like
(within reason). You don't have to keep up with anything.

-tony
Received on Thu May 13 2004 - 16:34:22 BST