The fascinating discussion Jim just started on buses got me thinking
again about a book I've been trying to track down for a while. While
it's not necessarily classic-computing-oriented, it's not really about
newfangled computers either; heck, I encountered it in 2003 or so, so
it'd be pretty dated by now.
Basically, I'm looking for a certain book (although really any book in
the same vein would satisfy), which was on computer system architecture,
organization, etc.; it talked about the usual boolean logic, assembly
programming in some fictitious instruction set, an overview of two
actual architectures (I think at that time they were 32-bit x86 and
64-bit POWER). The other thing I remember very specifically was there
was a place near the back (probably an appendix) that talked about
one or more specific buses (I think at least PCI was there), with timing
diagrams to tell you what was actually going back and forth between the
bus and CPU.
Like I said, I'm sort of keen on finding the exact book I had, but I
realize that's somewhat unrealistic, so I'm open to recommendations on
any book like that. And if it can cover the relavant concepts for both
classic and newish computers, that would be great.
Basically what I hope to learn is how you actually deal with
peripherals, add-in cards, etc., on the assembly language level, and
what that really translates into on a signaling level. I only really
know a little about how to do that in memory-mapped IO systems like the
Commodores (and to be honest I don't understand how the buses work
there, just how to poke and peek.)
On Tue, Nov 21, 2017 at 1:51 AM, Mattis Lind <mattislind at gmail.com> wrote:
> I think this is a 3/60 processor. Not 3/50.
I said 3/50 because that is what the silkscreen says. I found some
picture online and the 3/50 was a different layout. It sure looks like
Looking at some online schematics it looks like the P3 96 pin DIN
connector may only be for power. Is it possible to power this thing
through that connector without a proper chassis?
I know nothing about Sun hardware.
I'm picking my way through an LA30 restoration right now. It was pretty
filthy, so I've needed to pretty thoroughly disassemble it for proper
I noticed that a few of the thin steel ribbon springs in the paper path
are missing or broken on my unit, and some of the rubber bushings have
hardened and deteriorated. Long shot ask, but wondering if anybody out
there has spares of:
74-08648 (Spring, paper drag)
12-10357-3 (Bushing, rubber mount)
12-10358-3 (Ring, rubber mount)
Also, the maintenance manual recommends Molykote B2KR for lubrication in
a few places, but I can't seem to find specs on what this was. Can
anybody recommend an equivalent modern alternative grease?
> From: Fritz Mueller
> Overall, I have been pretty amazed by the sheer number of machined
> parts, castings, high quality bearings, etc. within this beast. Lots of
> stainless steel throughout. Sure wouldn't find anything built this way
> these days! What a tank.
That's DEC for you - quality engineering (mostly :-). Reminds me of this
Alas, that kind of engineering turned into a liability when DEC tried to
compete in the 'new world' of personal computers... :-(
> From: Charles Anthony
> a hybrid PDP-11 (16 bits) / PDP-15 (18 bits) on a shared bus (UNIBUS?)
That's a UNICHANNEL-15: it allowed devices on the -11 to do DMA directly into
the PDP-15's memory through the MX15-B Memory Multiplexer.
Odd factoid: this UNIBUS could run in 18-bit mode (!!), where the UNIBUS' two
parity lines were recycled into 2 extra data lines. Some DMA interfaces (e.g.
the RK11) could support this; in this particular case, it allowed the PDP-15
to use RK05 drives.
While working on some old (again!) half-inch tapes, I note that some of
the very old ones have an oxide coating about the color of milk
chocolate. Newer ones are anywhere from dark chocolate to black.
Reel construction is another aspect. The really old ones tend to be all
clear plastic, including the hub area. Newer ones have either a black
plastic reinforcement to the hub or employ an aluminum sleeve.
In most cases, the oldest of these is from around 1964, but probably
older than that, as the only clues I have are dates placed by the tape
librarian when a tape is put back into the pool or a label indicating
when the tape was last recertified.
Was there a date after which *all* half-inch tape became the dark brown
to nearly black in color?
I have a couple of vaxes that output 'unique' video, Alpha 3000 300,
Alpha 3000 400, Vax 4000 VLC, and Vax Station 3100 M76.
The Alpha and VLC each have a 3W3 type of connector and the 3100 has a
15 pin DEC designed connector.
What does it take to connect these to inexpensive, modern VGA light
On Nov 20, 2017 7:41 AM, "Tapley, Mark via cctalk" <cctalk at classiccmp.org>
Catching up late, sorry if this is an old question, but what did
the Digital Group computers use? My recollection is that they offered cards
with 6800, 6502, 8080, and Z-80 CPUs on the same bus, and that part of the
system seemed to work reasonably well.
The Digital Group had two separate buses, a memory bys and an I/O bus, as
well as two other slot types incompatible with either bus, for a CPU card
and a TVC (video and cassette) card. They didn't support interrupts or DMA
on any bus. If you wanted to use an interrupt, you had to wire it over the
top. Doc Suding said that he didn't put interrupts on the bus because
(paraphrasing) they are complicated and you don't need them.
As you say, they did support various CPUs, but not more than one in a
system. I wouldn't recommend that anyone consider The Digital Group as an
example of good bus design.