I have, surprisingly, a non IBM 1130 related issue to ask about. I have a
PIC16C55A-04/P 28 pin plastic MPU that I would like to reproduce --- but
don't have a PIC debugger on hand and in fact don't know whether or not the
existing device is code protected. (If it's code protected, then the path
forward is going to be very different).
Does anyone have the ability to check one of the chips that I have here is
code protected so I can see if I should pursue this any further?
Located in the San Francisco Bay Area but can mail a sample chip.
> From: Al Kossow
> It is in the Dick Best Options and Modules List 197503
Ah, thanks for the pointer; I see it's listed as a "Memory Extension
Control" - not sure that tells me much, alas!
Interestingly, it's not in the earlier Options and Modules lists, e.g.
June '74, but the KS11 is in that earlier list, so the MX11's a later
While I asking on the TUHS list about the KS11, someone mentioned the MX11
Memory Extension Option, described as "enabl[ing] the usage of 128 KW memory
(18-bit addressing range) ... developed by the Digital CSS (Computer Special
I'm not familiar with this, and I couldn't find anything about it. (It's not
even in the Spare Modules Handbook, but then again, neither is the KS11 -
although the KT11-B is). Some early UNIBUS device address lists (e.g. the '72
"peripherals and interfacing handbook") list up to six, from #1 at 777600-06
to #6 at 777650-56.
I can _guess_ what it did, from the description above (e.g. maps an 8KB block,
since there can be up to 6), but I was wondering if anyone had any hard data;
e.g. memories based on using one BITD, etc, etc.
Even a high level description (e.g. 'sat on the UNIBUS between the CPU and
extra memory, and mapped a fixed block of low UNIBUS address space to a block
controlled by a register') would be an improvement on what we have now, which
is basically nothing.
Someone gave me your info. I have a very important tape I need help with. The tape spooled off the end and I need the belt put back on. Maybe getting the data off the tape too.
It?s a 3m dc2120 120Megabyte tape.
I?ve tried to do some practice tapes with junk tapes but I?m not confident enough to do it.
> From: Steve Malikoff
>> According to this page that Dennis Ritchie wrote ...
> It states that their 11/20 had a KS-11 memory management unit, was
> that mandatory for running v1 Unix on an 11/20?
Well, the page does say they had two -11/20's, apparently one with and one
without the KS11.
Also, ISTR that the source for the -11/20 system has been recovered from a
listing and run, and IIRC that didn't have the KS11 stuff in it (but it
might be worth checking).
Next to nothing is known of the KS11. Dennis' page "Odd Comments and
Strange Doings in Unix":
has a story involving it (at the end), and that is all I've ever been able
to find out about it (if anyone has anything more, please let me know).
My original guess as to its functionality, from that, was that it's not
part of the CPU, but a UNIBUS device, which perhaps maps addresses around
(and definitely limits user access to I/O page addresses). It might also
have mapped part of the UNIBUS space which the -11/20 CPU _can_ see (i.e.
in the 0-56KB range) up to higher addresses, where 'extra' memory is
However, on re-reading that page, I see it apparently supported some sort
of user/kernel mode distinction, which might have require a tie-in to the
CPU. (But not necessarily; if there was a flop in the KS11 which stored
the 'CPU mode' bit, it might be automatically cleared on all interrupts.
Not sure how it would have handled traps, though.
I'll have to enquire on the TUHS list.
I've recently acquired an RK05 that's missing the lenses for its indicator
Does anyone know a part number or where I could find replacements?
I was hoping there would be a clue in the engineering drawings, but
mosst at sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org
I'm looking for some reliable RSS feeds (I appreciate they seem to be coming
rare these days) to do with classic computers, preferably with a TRS-80
flavour but I'm not going to be precious about it.
Google didn't seem to produce too many and those it did were either not
there anymore or broken or monumentally out of date.
If anyone can point me any where I'd be most grateful.
0418 815 527
My warehouse will be open on Sat, Jun 22, from 10-3 for anyone that wants to
come scrounge. I am 1 hour from San Antonio, or 2.5 hours from Austin, or
4-5 hours from Houston or Dallas (in decent traffic and weather).
1613 Water Street
Kerrville, TX 78028
sales at elecplus.com
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