21 Jan
2009
21 Jan
'09
12:35 p.m.
Paul Koning <Paul_Koning at Dell.com> wrote:
I think he might have meant PRO-385 as an improvement on the PRO-380...? :-)
However, the J11 originally didn't deliver the planned 20 MHz, but it
sure delivered more than 10 MHz. The reason the PRO-380 stayed at 10 MHz
anyway was because the support chips DEC used for the PRO couldn't
handle higher speeds. So even though the J11 could deliver atleast 15
MHz (which is what the 11/53 and 11/73 uses) and probably 18 MHz (which
is what later 11/73 and the 11/8x use), the PRO (unfortunately) stopped
at 10 MHz (which you can't blame on the J11). Even worse (I think) is
that P/OS never supported split I/D space, nor supervisor mode, so the
PRO makes very little use of the J11 cpu.
(The 11/9x machines eventually used 20 MHz J11 cpus.)
>>>> >>>>> "emu" == emu <emu at e-bbes.com>
writes:
emu> Quoting Gordon JC Pearce MM3YEQ <gordonjcp at gjcp.net>:
>
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=12036621970
>
> Two things I wonder about: How many has he got, and how hard would
> it be to make an SBC-6120-alike for the -11 with that?
emu> What's wrong with the original J11's ? I think they look even
emu> nicer than the black ones ...
emu> And then you could make something like a PRO-385 ;-)
Wouldn't it be a PRO-380? Well, unless you can clock it at 20 MHz
which was the original plan for the 380, but the J-11 failed to
deliver so they ended up at 10. Note that making a PRO-38x means you have to reverse
engineer the I/O
control gate array and the video hardware, both of which are likely to
be serious exercises in masochism. (Why reverse engineer the most
bone-headed I/O design in the history of DEC?) Either that, or a lot
of discrete parts to make a PRO-350 clone.
I couldn't agree more. :-)
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol