Playing with Junk 26 - DEC PDP 11/34 from 1978 - Page 1
Forum section: electronics / general

author: dexters_lab
author_rank: Unknown
timestamp: March 03, 2016, 10:08:38 am
content: is that your channel?been a subscriber since the M5000 server teardown a few months back

author: wkb
author_rank: Super Contributor
timestamp: March 03, 2016, 12:11:20 pm
content: People interested in PDP-11 / VAX-11 and other classic computers might want to take a look athttp://www.bejaardecomputers.nl/index-en.htmlGeert has gathered an extensive collection of classical computers, all housed in his big farmhouse. Most of them are in running condition.I myself make do with a PDP-11/83 and MicroVAX3000 housed in a MicroVAX2 cabinet, All running BSD Unix (what else..)

author: coppice
author_rank: Super Contributor
timestamp: March 03, 2016, 12:41:43 pm
content: I guess the 11/34 was the first round of PDP11s which dropped the long row of binary switches and lights.

author: rrinker
author_rank: Super Contributor
timestamp: March 03, 2016, 03:52:53 pm
content: Memories. At my first post-college job, they bought an old coordinate measuring machine that was both manual and automatic, the automatic drive controlled by a PDP11/T23. The computer was non-operational when it arrived, the manual part worked - a simple 8080 system with X, Y, and Z readouts and some simple math functions built in accessed from a keypad. I took the PDP11 apart and pulled and cleaned all the boards and managed to get it up and running. The supplied disks has RSX-11 for an operating system, along with a FORTRAN compiler and some other stuff. I managed to write some automated test routines for some of our parts. In case you don't know, a CMM is (in this case) a huge granite slab with a 3 axis carriage, a large bridge that moves fore and aft, a part on there that moves left and right which supports a column that moves up and down for the Z axis. All if it is VERY heavy, but the moving parts ride on air bearings so it is very easy to move by hand or via the servomotors (which could be controlled via a joystick or via computer control). Good hands on experience with the concept of inertia. At the base of the vertical shaft there was a sensor head with a very delicate ruby-tipped stylus which is what senses contact with the edges of what you are trying to measure. You can do things like find the radius of a bore, or distance between centers of two bores, or pretty much anything in 3 dimensions, with very high accuracy. Probably the coolest thing I worked on during my time there. Being a machine shop device, that PDP11 hadn't lived in the cleanest environment, but it really took only some good contact cleaning to get it operational again, and it ran quite reliably during my remaining time there. Amazing that I could have 3 user sessions going on all multitasking with just 4K of memory. Those removable drive platters were also something. Forget which model they were, but each drive unit was pretty heft, the platters themselves had a 2 part plastic case, you did a quarter turn of the handle to drop off the bottom cover then set the platter down in the drive unit like a top load clothes washer. I think they were like 14" in diameter, two platters in each cartridge, with a whopping 5MB per drive.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: March 03, 2016, 05:24:37 pm
content: Quote from: dexters_lab on March 03, 2016, 10:08:38 amDisclaimer: Not My Channel.

author: wkb
author_rank: Super Contributor
timestamp: March 03, 2016, 10:08:18 pm
content: Quote from: rrinker on March 03, 2016, 03:52:53 pmRL01 or RL02 disk packs?

author: rrinker
author_rank: Super Contributor
timestamp: March 04, 2016, 12:12:30 am
content: RL01's would be it, the 5MB version.

author: uncle_bob
author_rank: Unknown
timestamp: March 04, 2016, 12:38:24 am
content: HiMy first "home computer" was an PDP-11/20. No disks, only a model 33 Teletype to load it up. If I was lucky the pile of scrap boards might run for weeks before another repair was needed.Bob

author: SL4P
author_rank: Super Contributor
timestamp: March 04, 2016, 01:03:59 am
content: Quote from: coppice on March 03, 2016, 12:41:43 pmI think the 11/04 (a refresh of the 11/05) was the first - a little while before the 11/34I liked both panel systems...BTW I recall the pushbutton panel was driven by an Intel 8008 CPU !(I worked for DEC (#118138) at the time.)

author: MarkF
author_rank: Super Contributor
timestamp: March 04, 2016, 01:17:06 am
content: My first job used Honeywell 516 and PDP 11/55s. And lots and lots of punched cards........

author: wkb
author_rank: Super Contributor
timestamp: March 04, 2016, 09:24:24 am
content: Quote from: rrinker on March 04, 2016, 12:12:30 amThe one with grey handles, RL02 had DEC-blue handles. That is IIRC..

author: rrinker
author_rank: Super Contributor
timestamp: March 04, 2016, 01:30:41 pm
content: Quote from: wkb on March 04, 2016, 09:24:24 amAfter looking at pictures, such as here:http://www.pdp-11.nl/peripherals/disk/rl-info.htmldefinitely a pair of RL01's on the machine I used. ANd after reading that page, I'm surprised any of it actually worked - when they transported all the equipment they just used a forklift to load it all on a flatbed trailer (the CMM is HEAVY - the base is a huge chunk of granite) and the most definitely did not lock the heads on the RL01's before loading it. In fact I think the disk platters were in both drives.

author: Unknown
author_rank: Unknown
timestamp: March 04, 2016, 03:37:32 pm
content: One of my first tasks back when I was an apprentice was transferring caty programs from LP sized floppy disks onto a new fangled IBM XT via a serial link. The host system was an old PDP11, not sure which one but it was the type where the boot loader was stored remotely in the head of the grey beard at the end of the corridor. Back when computers were interesting things, sitting amongst several racks of camac modules it was like being on the set of a sci fi movie.

author: coppice
author_rank: Super Contributor
timestamp: March 04, 2016, 04:40:22 pm
content: Quote from: Z80 on March 04, 2016, 03:37:32 pmYour memory must be failing. The big floppies were 8", and LPs were 12".

author: Mechanical Menace
author_rank: Super Contributor
timestamp: March 04, 2016, 05:02:12 pm
content: Quote from: coppice on March 04, 2016, 04:40:22 pm8" floppy, but upto 70" hard...

author: strangersound
author_rank: Regular Contributor
timestamp: March 04, 2016, 05:54:23 pm
content: Quote from: dexters_lab on March 03, 2016, 10:08:38 amThe M5000 teardown was good stuff. That's one of my favorite teardowns I've seen. Just the case is mechanical engineering pron.

author: wkb
author_rank: Super Contributor
timestamp: March 04, 2016, 10:51:38 pm
content: Quote from: rrinker on March 04, 2016, 01:30:41 pmHm, its been a while but I think RL0x might have some kind of autolocking mechanism. Would need to dig up a service manual to check. I once wheeled RK07 over a cobble stone parking lot, they didn't care, just worked on arrival

author: rrinker
author_rank: Super Contributor
timestamp: March 05, 2016, 03:41:39 am
content: Quote from: wkb on March 04, 2016, 10:51:38 pmThere was a procedure shown on the linked site from the manuals on how to lock down the heads for transport - but then, this stuff was all built like a tank so probably unless you dropped it off the back of a truck it would be fine.

author: stejep
author_rank: Contributor
timestamp: March 05, 2016, 05:09:34 am
content: I had a friend who had two PDP 11's and 3 Prime Mini Computers in his shed. Due to the power requirements he could only run a couple of them at the same time.It was really nice in then on winter nights.