We did a lot more debugging on the TC12 LINCtape controller.
We saw a 500ns glitch in the LMU MOTION signal that corresponded to a short
slowdown in tape speed. We will investigate this next week.
We entered the LINC instruction to check a single block (0707) in the left
switches and a block number (0777-0000) in the right switches. When we
pressed the DO key it should go to that block on the LINCtape. With large
block numbers (07xx) and with the tape positioned half way through the tape
it worked OK. With lower block numbers it sometimes could not find the
block and searched back-and-forth on the tape. The logic analyzer showed
that the block numbers were correct in a sequence of several blocks, and
then it will read a bad block number. The TC12 would tell the TU55 to turn
around, it would read a good block number, realize that it was going the
wrong direction, and turn the tape around. It would then read a good block
number, and then a bad block number, and turn around.
At this point we don't think that we are working with bad tapes, but the
problem might be in either the TU56 tape drive, or the TC12 LINCtape
controller. We see bad behavior in both devices so we will do as Charles
Lasner suggested and swap a TU55 and TU56 between the PDP-12 and the
PDP-8/I. This will let us test the TU56 with a known good TC01 LINCtape
controller, and test a known good TU55 with a questionable TC12 LINCtape
controller.
We ran the A-to-D converter test and were rewarded with a display on the
VR14 that showed correct operation of the knobs and A-to-D converters.
--
Michael Thompson
Hi all,
Out of curiosity, did anybody on here subscribe to any of the newsletters published by a company called Aresco back in the late 70s and early 80s? These newsletters were VIPER (Cosmac VIP), Paper (Commodore PET), Source (Exidy Sorcerer), and Rainbow (Apple II). Aresco also published a series of books by Tom Swan titled PIPs for VIPs.
I own several issues of VIPER, but I'm still looking for copies of the others. Does anybody have these newsletters in their collection?
Matt
Hi everyone,
I've made tremendous progress on my 3B2 emulator. It's being
implemented under the SIMH simulator platform, which has been a huge
help.
My WE32100 core is getting closer to being complete. I'd consider it
alpha quality right now, but it has enough instruction coverage to
pass the 3B2's power-on self tests and to (barely) run some of the 3B2
firmware mode tools.
Implementing the WE32100 core has been thanks to the processor manual
and assembly language manuals that are available on BitSavers, but
outside of the CPU, virtually all of my understanding of the 3B2's
architecture has come from studying the ROMs and the SYSVR3 source
code. I've also been helped by having remote access to a running 3B2
so I can assemble and disassemble code using the real AT&T tools.
Beyond that, I have found precious little documentation.
I'm at the point now where I'm pretty well stuck until I can find more
information. I understand large chunks of the memory map now and
should be able to do things like simulate the floppy and hard disk
controller, but there are large gaps in my understanding. There are
many undocumented registers that are used by the firmware, but don't
appear in the SYSV source code anywhere. What they mean and what
they're for is anybody's guess. I've just stubbed them out for now.
If anybody has access to schematics, architecture docs, or other
memory map information, I'd be eternally grateful if you could share
it!
-Seth
Hi all,
I have a PDP-11/55 for sale (Ottawa, Ontario, Canada). Bids open
until 2015 09 15, buyer to arrange shipping, I will have it wrapped
and ready to go.
Please visit:
www.krten.com/~rk/museum/index.html
For pictures, detailed inventory and contact info. Sealed bids via
eamil please. Winner will be notified 2015 09 16, machine will be
ready to ship same day. Must be shipped / picked up no later than
2015 10 09.
Sold AS-IS / where is, untested, unpowered since received.
Comes with H960 rack and 2 side panels.
Cheers,
-RK
--
Robert Krten
Visit me at http://www.ironkrten.com
+1-410-734-6804
New hobby thing. ;)
Wildcat! 4 running on it, stock out of box config. If you don't see all the
menus except for help and send to sysop, wait till I validate users. When I
get back home i'll set it to give non-validated users more permissions,
though.
--
Gary G. Sparkes Jr.
KB3HAG
> From: Ethan Dicks
> That looks like a great haul.
We're talking about the guy on eBay whom I posted a pointer to a couple of
days back, the one with large lots of QBUS CPUs, memory, DLV11s, etc?
> I hope they are working cards.
All the ones I've gotten from the guy above which I was able to test (couldn't
test, e.g. the RK05 cards 'cause I don't have a working RK05 yet) were OK -
QBUS memory, 11/23's, etc.
Noel
Here's a new picture of "George" -- aka the Philbrick analog computer
that MARCH rescued two months ago. It was used at M.I.T. from 1958-1970.
http://snarc.net/george.jpg
I'm making good progress on the MEM11 firmware. I spent the last few days
re-doing the firmware build environment. Previously, it would build all the
files each time. Now there is a proper Makefile (even though it takes about
a minute to build everything). I realized that I needed something
better than
what I had because there are multiple targets (emulator, FPGA eval board and
the MEM11 board itself). Right now I'm focused on getting as much debugged
on the emulator since it has a reasonable debuging environment.
I've also integrated various test programs into the build environment
and use
various low level code as part of the main firmware for hardware access.
This "kills two birds with one stone" since it tests not only the
various hardware
functions it also allows me to debug some of the firmware separately from
the full code base.
At this point, the emulator fully supports all of the J1 instructions
(and they
all work too!). In terms of I/O (that will be part of the MEM11 board) it
supports LEDs and various configuration inputs, FRAM, UART and timers.
The biggest risk that I'm taking is that the UART is emulated as being
directly exposed. On the MEM11 hardware, the UART will be connected
through a SPI interface which requires that all accesses to the UART are
asynchronous transactions.
The biggest piece of work remaining on the emulator will be emulating the
Unibus interface. The work here will mainly to create a means to script
various Unibus transactions.
However, before doing that, I'll be testing out the boot loader code and
the configuration firmware since none of that is dependent upon the
existence of functional Unibus hardware.
TTFN - Guy
Hi all,
I am trying to identify why my IBM 5151 display has no picture when
connected to a normal MDA card in a IBM PC 5150. So armed with an
oscilloscope, digital multi-meter and the SAMS Computerfacts for it I
started to investigate. First, the card does send out signal and that
signal does reach the board inside the monitor. I checked the power
part of the circuit, all diodes and the transistor check fine. I
probed some of the vertical and horizontal transistors and there is a
signal there too. Then on the video board both TR19 and TR20 have on
their collector and emitter (respectively) a signal (95Khz). What else
can possibly be wrong?
The SAMS manual talks about "injecting a video signal" at different
pins however I have no idea exactly how to do that.
So there is current going out of the power part and there is signal on
the video board attached to the neck of the CRT.
Regards,
Vlad.
