20 Jan
2015
20 Jan
'15
5:04 p.m.
From: Henk Gooijen
but RP11 will never be possible, isn't that
MASSBUSS!?
Maybe you're thinking of the RH70, the MASSBUS <-> PDP-11/70 memory bus
interface? But there was also the RH11, a MASSBUS <-> UNIBUS interface, which
supported all the same devices (RP04-6, etc) as the RH70, but plugged into a
UNIBUS. (The two were programming-wise almost identical, the RH70 had an extra
register for the extended memory address bits, plus a 'CSR3'.)
But I was speaking of the RP11, a UNIBUS interface for the RP03 (different
beast from the RH11, although very similar).
Noel
20 Jan
20 Jan
6:20 p.m.
-----Oorspronkelijk bericht-----
From: Noel Chiappa
Sent: Tuesday, January 20, 2015 6:04 PM
To: cctalk at classiccmp.org
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: MEM11 Status Update
From: Henk Gooijen
but RP11 will never be possible, isn't that
MASSBUSS!?
Maybe you're thinking of the RH70, the MASSBUS <-> PDP-11/70 memory bus
interface? But there was also the RH11, a MASSBUS <-> UNIBUS interface,
which
supported all the same devices (RP04-6, etc) as the RH70, but plugged into a
UNIBUS. (The two were programming-wise almost identical, the RH70 had an
extra
register for the extended memory address bits, plus a 'CSR3'.)
But I was speaking of the RP11, a UNIBUS interface for the RP03 (different
beast from the RH11, although very similar).
Noel
Ahhh, thanks Noel. My goof up. I associate anything "RP<whatever>"
with MASSBUS devices. I even wrote "BUS" with double S. Clearly a case
of finger movement on the keyboard before enabled brain activity ;-)
I have both RH11 (on my 11/35) and RH70 interfaces on my /70, but I
never saw any RPxx drive in real life :-/
- Henk, PA8PDP
7:21 p.m.
On 2015-01-20 18:04, Noel Chiappa wrote:
Correct.
One also needs to remember that the Massbus is a pure I/O bus. It's
never a CPU bus. So you always needs to have a bus adapter if you are
hooking up a Massbus drive to a machine. And of course, from the CPU
point of view, you then talk to the bus adapter.
So really, emulating any Massbus device on a PDP-11 is not a problem.
You essentially emulate the Massbus adapter, and whatever sits behind that.
And yes, for PDP-11s you had the RH11 that was the adapter, except for
the 11/70 which used the RH70. Software downwards compatible, but the
RH70 is more capable, in that it can do direct DMA to the whole memory
space of the 11/70, without using the Unibus map.
It's also a whole lot faster than the RH11, which means it can run some
devices that the RH11 did not support.
RP07, RM03, RM05 are the ones that comes to mind.
Probably also the TU78.
Johnny
From: Henk
Gooijen
but RP11 will never be possible, isn't that
MASSBUSS!?
Maybe you're thinking of the RH70, the MASSBUS <-> PDP-11/70 memory bus
interface? But there was also the RH11, a MASSBUS <-> UNIBUS interface, which
supported all the same devices (RP04-6, etc) as the RH70, but plugged into a
UNIBUS. (The two were programming-wise almost identical, the RH70 had an extra
register for the extended memory address bits, plus a 'CSR3'.)
But I was speaking of the RP11, a UNIBUS interface for the RP03 (different
beast from the RH11, although very similar).
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