I picked up this system from its previous caretaker yesterday, to hold onto for a friend. I’ve also inventoried the major functional ICs and archived the “IPL-M” ROMs.
Here’s what’s in the Eagle-32:
- Main Logic Board
- 8MHz 68000 CPU
- 2x D8255 programmable peripheral interface
- left 8255 is clearly for parallel and user port
- right 8255 I strongly suspect is for hard disk, possibly ANSI or SASI
- D8253C programmable interval timer
- 2x 2651N programmable communications interface for serial ports
- 2x 2716 for IPL-M 0/1 ROMs
- Disk Controller Board
- FD1701B-02 floppy disk controller
- No video board, whether text or graphics
Since there’s no video board in the system, and a couple of cables internally that aren’t attached to anything, I expect it was removed by a previous caretaker. This is sad because without one it’s unlikely to come up, not that anyone has found any software for it. On the other hand, there are zero PALs, so both full reverse engineering and maintenance should be straightforward.
I threw the 4KB of boot ROM in Ghidra and confirmed a couple things:
- At boot, ROM is mapped to 0, and then remapped either by a write to the location or by a cycle counter: The initial stack pointer at 0x0 is 0x0001fffe and the initial program counter at 0x4 is 0x00ffc026, indicating the ROM is normally located at 0x00ffc000.
- The ROM freely interchanges addresses in the 0x00ffc000..0x00ffffff range and addresses in the 0xffffc000..0xffffffff range, which is annoying to deal with in Ghidra.
- I/O devices appear to be in the 0x00ff8000..0x00ffbfff range, all of the devices accessed via the bootstrap seem to be barely above 0x00ff8000.
- Only NMI, bus error, interrupt 2, and interrupt 5 are set up by the bootstrap.
- The bootstrap is very bare-bones but still has a bunch of indirection in it; it’s obviously written in assembly, but it does seem to have parameterization so it may support both console and serial I/O.
I suspect that I can figure out from the pattern of I/O accesses which devices are at which address in the memory map, at least if I bring up an emulation in MAME. That should at least allow writing new code for it, and _maybe_ even figuring out which CRT controller the video hardware uses and where in the memory map it is. (I suspect the 6845 and/or 6847 just from the time period, but who knows? Gotta see what it actually do when trying to show the “IPL IN PROGRESS” string contained in the ROM, or one of the couple error strings…)
— Chris
Perhaps slightly off topic, but perhaps someone here has a contact or idea
on how to get started on this:
Someone has done a Q-Bert port in 2023 to a new system. The title is
different, but the "look and feel" (and audio) is pretty "authentic" to the
original (not sure if using exactly the same original tiles and such, I
believe it was all original work - but still, it's very much an
arcade-style clone). We see now that Sony "owns" it these days (I seem
to remember decades ago there a Q-bert cartoon? But perhaps remembering it
wrong).
The question is, how would one start on obtaining a license? I assume it
wouldn't be cost effective (for a free casual port), but still just
curious. I've tried to contact Sony in the past (on a different software
title), but it's just a huge enterprise it's a bit challenging to
approach. Just wondering on the off chance if maybe someone around here
has gone down this road already?
-Steve
I am back to playing with RSTS/E 10.1 again and have a couple questions
if there is still anyone around with experience.
First: Is there a way to change the allowed length for passwords?
Second: Is there a way to make login take the assigned name rather than
the x,x format for logins? I seem to remember using a system once that
did but I have no idea if it was legit or a local hack. Although I have
no problem using local hacks. :-)
Need to get a system going and maybe even join HECNET.
I really wish there was TCP/IP for RSTS.
bill
I have been scanning in a lot of manuals that I have that relate to
computers that are not in my collectiion, but which may be unique, or
nearly so.
Today I scanned in the Sorbus Micro Handbook 1990 Update, which has
information provided to Sorbus FEs who might service various microcomputers.
There is info in there on all sorts of stuff, including motherboard
jumper/switch info up through a PS/2 model 80, for example, and lots of
other manufacturer's computers and expansion cards, stuff like IOMEGA,
AST, Zenith Tandon, etc. etc.
It can be found in my Google drive under my directory of things I have
provided for bitsavers to snag:
https://drive.google.com/open?id=0B2v4WRwISEQRWWFFdVpCZWFTZEU&resourcekey=0…
in subdirectory pdf/sorbus
JRJ
Did IBM ever publish programming information for their PC SDLC or BiSync communications boards? I’m wondering about the possibility of programming one to drive the synchronous protocol needed for “booting” a Northstar Advantage over its serial port.
Or, for that matter, wondering what Northstar had in mind when they made that protocol synchronous - what would they have had driving it?
ok
bear.
Hey all!
I'm looking for a couple "file manager" type pieces of software. I can't
find them on WinWorld.
First one is from about 1984-1985, possibly called DRBOSS.COM, I just
remember it used IBM extended graphics for "window" borders (which were
colored red) and the filenames were either in gray or green. The main
feature was you could select a few files at a time, then do some operation
on those selected ones. And as a .COM it was well under 64K.
The other is from around 1996, and called MWIZ or Menu Wizard. Apparently
there were a few variations with possibly the same/similar name. All I
recall about this one is it came with both a .EXE and a .COM, and was
written by a person named Tony. I believe it was available on the '96 or
'97 BYTE magazine CD, and possibly also on CompuServe (I'm not current on
what the state of any CompuServe archives are these days).
Not urgent - just curious if they could be found.
And if anyone is in an MS-DOS mood throughout the holiday break: I still
find my ancient CDIR.EXE useful even in DOSBOX or on my physical IBM 5150.
It is available in my utility collection archived here:
https://github.com/voidstar78/VUC4DOS
For other early IBM PC notes (like floppy drive emulators and NIC setup), I
have some notes here: https://voidstar.blog/ibm-pc-5150-notes/
(including all about using the tape deck!)
-Steve / v*
I think I have got my VT100 basically working now except for the actual
video display. I think there is a problem with the transistor that drives
the flyback transformer. This is Q414 on page 58 of the Feb82 schematic on
BitSavers
(https://bitsavers.org/pdf/dec/terminal/vt100/MP00633_VT100_Schematic_Feb82.
pdf). I have removed it from the circuit and tested it with the diode tester
of my multimeter. It does not test as two diodes, indeed across
Collector-Base the multimeter beeps for a short circuit, and so I am fairly
sure it is bad,
The part is the one with the heatsink as shown in this picture:
https://rjarratt.files.wordpress.com/2023/12/img_20231221_112305.jpg. I have
found some information on it here:
https://www.web-bcs.com/transistor/tc/b0/B411.php but the Feb82 schematic
shows it is a BU407D. My video board is not exactly the same as the one in
the schematic despite having the same DEC part number, but the circuit that
drives the flyback is the same on the secondary side of T403, and includes
the optional diode CR406 in the form of another B411 transistor that is not
connected at the emitter.
I am trying to identify a replacement and could do with some help
identifying one. I can't find a full datasheet for the B411, all I can find
is this https://www.web-bcs.com/transistor/tc/b0/B411.php, which seems to
match the part I need to replace, and I have also found one for a BU407 (not
BU407D) here https://www.mouser.co.uk/datasheet/2/308/1/BU407_D-2310257.pdf.
I have tried to find something that meets or exceeds the voltage, current
and switching time specs. I have found a couple of possible replacements and
would welcome opinions on their suitability:
https://www.farnell.com/datasheets/2861437.pdf
and
https://www.farnell.com/datasheets/3033460.pdf (assuming that the switching
times are a typo and they are in microseconds rather than seconds)
Do these seem like suitable replacements?
Thanks
Rob
Happy DEC-20 Day!
My late friend Mark always noted that TOPS-20 (and the DECSYSTEM-20 on which it
runs) was a great improvement on its successors.
I wish you all a joyous Winter Solstice Festival, however you may choose to
celebrate it.
Rich
The PDP 11/34 and 11/04 front panels (both operator and programmer) use a
somewhat stiff plastic sheet of 1.0 mm thickness with DEC logo, model
designation, labels for the keys printed on it, cut-outs for the keypad and
knob and red transparent sections for LEDs and 6 digit 7-segment display.
I don't know what the industry calls this type of plastic sheet? Is it a
"decal"???
This plastic sheet is (was) fixed to an anodized aluminium plate (1.6 mm
thickness) using some type of glue which has deteriorated so that the
plastic sheet has separated from the aluminium plate.
The glue looks like it has been sprayed on and has a light yellowish-brown
appearance. The glue readily dissolves in ethyl-alcohol and acetone, but is
unaffected by water, petrol (gasoline) and dry cleaning fluid (white
spirits).
I would like to glue the plastic sheet back onto the aluminium plate, but
worry about damaging the plastic sheet and/or paint by the solvents in
typical glues.
Also some glues don't allow any adjustment once you combine the two halves
of whatever you glue together.
What type of plastic is this plastic sheet likely made of (polycarbonate?)
and what paint was used? I am asking to determine what solvent based glues
may attack either the plastic sheet or the painted surfaces.
The dark grey and transparent red paints are applied to the back side of
the plastic sheet, so they are vulnerable to solvent attack when glueing. I
tried ethyl-alcohol in one corner which is obscured by the cast metal
surround and some of the dark gray colour came off with the alcohol and
gentle rubbing.
Has anyone successfully glued back the plastic sheet to the aluminium
plate? If yes, what type of glue did you use and how exactly did you do the
operation?
Any suggestions, advice or tips?
Thanks and best regards
Tom Hunter
