--- Joe <rigdonj(a)intellistar.net> wrote:
> OK all you DECheads, here's a question for you. I have a DEC core memory
> board that says H213 on the handle. A stick on label on the back says "4K
> x16" but etched into the board it says "16k x 19 bits". Why the
> difference? (I know about parity so forget the extra three bits.)
Can you see the core mats or is there an opaque cover? I have some stuff
that may be the same thing you have (from an 11/05). Mine is marked
similarly, but three of the mats are blank.
I suspect that the same PCB could be used in several machines, including
an 18-bit machine w/parity, depending on how many mats were wired.
-ethan
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Sorry about my omission from the previous message; I meant the card-to-drive cabling,
not the card-to-card cabling.
Thanks!
-Sean Caron (root(a)diablonet.net)
-----Original Message-----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Saturday, December 11, 1999 6:57 PM
Subject: Re: Weirdest RK05 problem I have *ever* seen.
>>
>> I have not even begun to look at the drive yet but I thought I would
float
>> the problem here in case someone has actually had something happen as
weird
>> as this.
>>
>> PROBLEM: Both drives don't work.. only "Write Protect". Is you tip either
>> drive on it's left side they work fine, (blower starts up, lights,
>> everything..). [not the right side]
>
>Are you saying that tipping one drive on its side makes _both_ of them
>come up?
>
No.. even weirder.... Take any one drive (they are not connected
together)..and plug it in. The 5V supply works (Write Protect).. nothing
else happens. Flip EITHER drive on it's left side and it happily comes up!
I can't believe both drives have the same problem. Also, both drives have a
bad -15V when mounted.. flip it on its side and away it goes...
>>From what I rememberm the blower is controlled by a relay on the relay
>board on top of the PSU chassis (rear left of the drive). The other relay
>controls the spindle motor. The blower relay is controlled by either ACLO
>or DCLO (I forget which), which, of course, is bussed between the drives.
>I'd start there -- sounds like something is pulling that line active, and
>turning off the relay.
>
Yes.. the control logic won't let anything come on unless all three supplies
are functioning right.. -15V is the problem.
>>
>> Looks to be PSU problem but I have not popped the top yet.
>
>Possibly, although WrtProt working implies the PSU is doing something.
Yes +5V is okay on both.
>
>>
>> In all the years I have worked on RK05s I have never seen this!
>
>Ditto...
>
I have 13 right now but 11 are 2 hours away.... so I have to get these
running quickly to test the 8A.. (it seems to be running).
>Do you have the prints? I'd certainly start by looking at that relay
>board (take care -- live mains!!!) and the signals that control it.
>
Yes.. but again far away - storage (my home is filled with older PDP-8
stuff right now).. I went on highgate and had a look. It will be nice to
have a print set for everything next weekend (no more travelling).
john
PDP-8 and other rare mini computers
http://www.pdp8.com
>-tony
>
>
OK all you DECheads, here's a question for you. I have a DEC core memory
board that says H213 on the handle. A stick on label on the back says "4K
x16" but etched into the board it says "16k x 19 bits". Why the
difference? (I know about parity so forget the extra three bits.)
Joe
Just came in last night:
PDP-8A500 with:
M8315 \
M8317 > CPU, clock, serial, parallel
M8316 /
H219B - 16K core
M8365 - printer
M7104 \
M7105 > RK8E RK05 Disk Interface
M7106 /
Also got two RK05 drives with the M993 RK05 cable.
I got a disk pack filled with diagnostics for all the Dec devices and Dec
x/8.
Pretty cool.
It looks to be in running condition.
A few 8Es and another 8A coming in this week. Next weekend a UFO will be
dropping off 50+ PDP8s and PDP11s.
john
PDP-8 and other rare mini computers
http://www.pdp8.com
Well, I can't say much from the Amiga side, but after playing around with
Macs for a number of years, I don't think there were really any instances
where instructions were _removed_ that broke software... I do remember
there were a few specific issues when features were _added_ and a lot of
software broke, like when the 68020 macs were introduced with onboard
caches that broke some software that used self-modifying code, and when
the 68040 was introduced with its onboard caches, I think it ended up
breaking some software as well. This is all mac-related stuff, though,
so I don't know if there were ever any similar issues over on the Amiga
side.
-Sean Caron (root(a)diablonet.net)
-----Original Message-----
From: Ethan Dicks <ethan_dicks(a)yahoo.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Saturday, December 11, 1999 5:40 PM
Subject: Re: Two PDP-8A questions
>
>
>--- John B <dylanb(a)sympatico.ca> wrote:
>> I hope someone can answer these questions...
>>
>> Where does the 16 pin front panel connector plug into the main options
board
>> and which way? (There are two sockets on the Options board)
>
>It doesn't. It plugs into a 16-pin header/ribbon cable that comes from the
>backplane. The two empty sockets are for user boot roms.
>
Thank you. I don't get books on all these systems until next weekend.
>> Where does the main serial line plug into (which port on which board)?
>
>The DKC8AA (I don't have the handle number here) - it has two Berg
connectors
>facing front (for the full front panel) and three facing backwards - the
>one closest to the edge fingers is the serial connector. The other two,
>for the sake of completeness, are 12-bits in and out. The output port can
>be used to drive an LA-180, but the data is inverted from normal and the
IOTs
>are not the same. With a recompiled driver, however, you could drive a
>parallel printer with it.
>
Okay thanks.. I will work on the RK05s now.. they both have a bad -15V
supply...but bioth work fine when tipped on their left hand side.
>Do you need a copy of the 1977-1978 microcomputer handbook? I have a
spare.
>Let's talk.
>
>-ethan
>
>
>=====
>Infinet has been sold. The domain is going away in February.
>Please send all replies to
>
> erd(a)iname.com
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>
In re-reading the PDP08 FAQs, I came across a mention that the older KK8E
cards (three digit handle numbers) are somehow "broken". Can anyone elaborate?
I have a couple of KK8E sets, one with the M833 timing module and M865 20mA-
only TTY interface. What might be odd about them? I need to be able to use
the M865 as I only have one M8650 KL8J interface (with two cables - one EIA
and one 20mA, but the 20mA cable is missing the Berg housing - it's a bundle
of loose connector pins on the interface end).
Speaking of cables, I was attempting to build a new cable for my PDP-8/a and
re-discovered a minor detail - the DKC8AA has this interesting feature - the
EIA input and the TTL input to the serial hardware are not connected at the
board level. There is this loopback wire that must be installed on the Berg
connector to get the input data into the hardware. I remembered this after
much frustration from the days when I used to get discarded cables from my
former employer who made sync serial hardware. We shipped a nearly-fully-
compatible cable with each and every one of our boards. All I need to do to
convert these to PDP-8/a use is to add that jumper wire. If anyone is in need
of a Berg-to-DB25 cable, let me know. I have a box of them that can be
converted to PDP-8 use (for a nominal fee, of course ;-)
-ethan
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--- "Zane H. Healy" <healyzh(a)aracnet.com> wrote:
> Unfortunatly I don't remember where I read that for sure, and I'm not 100%
> sure it's the Dragonball, but the Dragonball sounds like the right follow
> on processor.
I recall the same thing.
> I think I read it in the TEAM Amiga Mailing list, in one of
> Dave Haynie's posts, but like I said, I don't remember.
I did see Dave Haynie mention that there were some fundamental differences
in the Dragonball that caused binary-level compatibility problems, but I
don't recall the specifics, either.
> However, I think even some of the 68040 and 68060 series chips don't have
> all the instructions of earlier processors. We got any 68k pro's around
> here?
For all practical purposes, the differences with the 68000 and the '40 (and
higher) are more related to priv'ed instructions, not missing instructions.
There may be some missing ones, but they are not ones that were well used
(BCD packing and unpacking instructions come to mind, but I'm not 100% sure
of that). Cache and timing issues for instruction-set-dependeng loops are
much more of a problem. Because the 68K family didn't change as massively as
the Intel x86 family, programmers tended to use cycle-counting loops more often
than they should. Who here remembers the first generation of VGA games that
didn't run right on the 486 because the loops were running too fast? DOS
programmers learned their lesson years ago when poorly-written software broke
with every new hardware design. Such things came more slowly to the Motorola
world.
The first compatibility problem came with the 68010 and the MOVEcc
instruction. It's unpriv'ed on the 68000, and priv'ed on the 68010
and up. AmigaDOS provides a call to extract the relevant condition bits
that one is supposed to use. The practical solution was to install an
exception trap to handle when some errant programmer used the forbidden
instruction and emulate the real thing. It's much, much slower, but
it's the kind of thing that doesn't get executed in a loop, so wall-time
execution speed is essentially unaffected. For the trivial-minded, the
AmigaDOS calculator that came with AmigaDOS 1.1 uses the offending instruction
and makes a good test that the exception handler is installed.
-ethan
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--- John B <dylanb(a)sympatico.ca> wrote:
> Okay thanks.. I will work on the RK05s now.. they both have a bad -15V
> supply...but bioth work fine when tipped on their left hand side.
I saw that posting. How odd. I have a similar problem with one of my
PDP-8/Ls.
A retaining nut is loose on one of the three fuse holders. IIRC, the RK05 has
an external circuit breaker, but no exernally mounted individual fuses like the
power supplies from the late 1960s. I'd suppose your problem is some kind of
loose component or connection, but I couldn't suggest where to look.
-ethan
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