On Friday 14 May 2004 08:45, Tom Uban wrote:
> >So, what devices would give us the largest range of possibilties for
> >software compatibilty at the larges size?
>
> I'm thinking RK11 and RP11.
I'd tend to agree with that, and add at least an RH11 (massbus)
controller to that, so you have access to large-ish disks (RP07/516MB).
As a starting place, I'd probably use an RL11 as the programming
interface looks very simple (4 registers) and I've got a real one that
I can test against.
> >If we're to use a microcontroller to run this board, then it'd be
> >possible to have "changable firmware", and either change it to
> > emulate the type of device you want, or to emulate multiple
> > devices. On second thought, you probably don't need a
> > microcontroller for that, but it seems easier than going the
> > FPGA/PLD route to do it.
>
> An FPGA would potentially allow for a large number of registers all
> in a single package, that could be "re-wired" as necessary after the
> design was completed. If discrete logic is used for the registers,
> then the design will end up being fixed. A micro-controller would
> allow for the management of the disk space independent of the PDP-11.
Right. I'd consider doing this with a couple of PALs and a
microcontroller for my first run at it. After working with FPGAs at
school, I vehemently hate having to write VHDL for them. As well, PALs
use cheaper development tools, and are usually cheaper for small,
simple designs, and if you chose the right ones (AMD's PALCE line),
they're easily erasable.
> I'm not sure how much it matters if the emulated controllers match up
> with the physical ones that we have or not. An RL11 shouldn't be much
> more difficult than an RK11 emulation.
In fact, I think it'd be simpler, but I haven't looked closely at it
yet, so I might be wrong.
> >For the actually data storage, I think you'll want to use flash or a
> >writeable hard drive (perhaps even a 2.5" laptop IDE drive mounted
> > on the UNIBUS controller card). It seems novel to have a 8
> > (emulated drive) x 516MB (4GB total) UNIBUS storage card that takes
> > up a single SPC slot.
> >
> >Hey Tom, have you started at all on your RK11 emulator? Want to
> > compare notes on this?
>
> I've started thinking more about it, so if that counts... I've also
> been collecting people's comments on the idea over the years. When I
> get started in earnest depends on what my schedule ends up looking
> like this summer.
Ahh, you're about where I am with this. With any luck, I should be able
to start working on this really soon, perhaps as soon as this
weekend. :)
Pat
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Received on Fri May 14 2004 - 10:48:17 BST