Disk hardware emulation, was Re: Grandfather system RTE6/VM?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Dec 10 18:44:45 2003

>
> On Wednesday 10 December 2003 10:47, Peter C. Wallace wrote:
> > Usually you know the encoding scheme, and I dont see anything wrong
> > with using whatever knowledge you have of the interface to optimize
> > it. If a different encoding scheme is used, an FPGA based design
> > could easily adapt.
>
> "Knowing the encoding scheme" prevents this from being a "universal"
> interface. You'd need to make different version for, say, your PC/XT,
> your PDP-11 with an RQDXn, and TeleVideo TS816. (Or shouse I say "my"

Let's add the PERQ 2T2, the OMTI5200 series controllers (used in PERQ
3a's, Torch XXX's, etc), the Adaptec ACB4000, the Xebec whatever, the
Xeroc Daybreak, another Q-bus PDP11 controller, which pretends to be an
RP-something on the PDP11 side (it doesn't use MSCP), and a couple of
others.

> as those are all system I have that'd benefit from this). At most, (I
> think) you'd need a different cable set for all three of these if you
> didn't claim to "know" the encoding.

Don't all ST506 drives have a 34 pin control connector and a 20 pin data
connector? There were a couple of changess to the former (most common
being that pin 2 (IIRC) changed from RWC/ to HS3/) but apart from that,
the pinout was standardised.

> Also, with at least two of these examples, you probably *don't* know the
> encoding method... as mentioned earlier, the RQDX(1) isn't based on any
> 'standard' controller IC. Also, the TeleVideo's controller is based
> upon an 8X300 microprocessor, and may not be RLL/MFM/FM.

At least you _could_ trace out the schematics (if you don't already have
them) and disassemble the 8X300 code. No I am not suggesting you need to
do this, but it's a lot easier than figuring out what happens inside an
ASIC..

-tony
Received on Wed Dec 10 2003 - 18:44:45 GMT