There were a number of electronic 'desk' (meaning the 'size of a desk') calculators that were developed in the late '50's and early '60's. These included the IBM 610 "Autopoint", the Monroe Monrobot I, II, and III, the Clary DE-60, and others that I can't recall off the top of my head. These machines were generally programmable in some, generally by storing learned steps (learn mode programming) on the drum or paper tape. All had magnetic drums for storage of working registers, and, in the case of the IBM 610, the drum also stored program steps. These machines all utilized tube or early transistor electronics, and generally interfaced to punched card or paper tape units, and IBM output typewriters or Friden Flexowriters for output. These machines were the precursors to desktop-sized programmable calculators such as the Mathatronics Mathatron, Olivetti Programma 101, Wang LOCI and 300-series, Monroe EPIC 2000/3000, Friden 1152, Wyle Scientific, and the HP 9100A. In the late 1960's, SCM made a machine called the 7816 that used a fixed-head magnetic disk for register storage. It was a four function calculator in a 'desk' that had two paper tape readers, two paper tape punches, an I/O typewriter, and a calculating unit that was programmable via the paper tape readers. It used transistor logic, and a bit-serial architecture.

The big difference is that the disk has flying heads which essentially set their own working clearance, the drum has haads fixed to the chassis (which are adjustable for running height when the drum is set up). You need a pretty low run-out in a drum's bearings. Incidnetally, I have a graphics display for a PDP11 using a fixed head disk. The disk rotates once per video frame (or maybe field, I forget). The video data is recorded using analogue FM recording on a track of the disk -- 3 tracks for R,G,B, and you can switch heads to switch between images. There's some electronics to DMA data from the PDP11's memory (it connects to a DR11-B interface), feed it into a DAC and FM modulator, and record it on the disk. It's not hard to do this if you don't mind the head touching the media (tape) as it does in a cassette recorder, but the life of the tape is probably too short to use for serious data storage if you do this -tony

On Fri, 26 Mar 2004, Peter C. Wallace wrote: LGP-21 fixed-head-platter mechanical memory (main store, not "disk") the heads sit crashed (sic) and lift when up to speed. The platter surface has fine scoring -- it's normal. It's only 80 bits per inch. Nickel plated steel. In fact, there's little springs that press the heads DOWNWARD.

Tony> FWIW, the springs on hard disk heads press the heads _towards_ Tony> the platter too. Look at something like an RK05 sometime. The Tony> heads are lifted by flying on the air dragged round by the Tony> platter. Drives like the RK05 retract the heads as part of spindown, so the heads never land on the platter. They only load when the disk is up to speed. Gravity is a component of the head loading force, which is why the "up" and "down" heads are different -- different springs. paul

Tony> You hope... If the power fails and your NiCd pack isn't any Tony> good, then the heads will land on the platter with nasty Tony> results... NiCd? You must be thinking of the big capacitors (not batteries) that do the emergency head retract in the event of powerfail. Tony> Anyway, the 'ting' when the heads load on an RK05 is claimed to Tony> be the heads bouncing off the platter, so they may well touch Tony> for an instant. I rather doubt that. The sound is no different from the "ting" sound you hear when the head actuator seeks. paul

3 cell? My RK05s have 4 cells, RK07s have 8... Nothing. The RK03 (Diablo model 30) have a head load solenoid that lifts the heads off the platter when de-energised. This obviously does the Right THing if the power fails. -tony

No, I am thinking of the 4-cell NiCd pack (look to be 1/2AA size cells -- it's certainly the same pack is in some cordless phones) on top of the PSU chassis (rear left) in an RK05. It's connected to the positioner coil via one of the relay contacts and the home microswitch to cause an emergency retract if the relay drops out i.e. if the mains fails. It's certainly a battery and not a capacitor. I do know the difference, I've read the RK05 printset, and in fact I've replaced the batteries in all my RK05s (and, indeed my RK07s, which have an 8-cell pack under the chassis). I can certainly tell the difference. There is a very metallic ring when the heads load, but not when they seek. -tony

On Wed, 31 Mar 2004, Ethan Dicks wrote: The Librascope L321 fixed-head drive I've got is coated with cobalt according to the literature. -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]

On Wed, 31 Mar 2004, Hans B PUFAL wrote: The label on this is stamped with a model number of L-321-1. I have literature for the Series L-300 with the following characteristics: Power requirements: 115-volt, 60-cycle, single-phase AC Disc diameter: 10 in. Weight: 25 lbs. Axis of rotation: Vert., horiz., or any combination Recording diameters: 4.7 in. to 9.2 in. Number of tracks: 45 (5 groups of 9) Number of registers: 4 Register length: 0.25 or 0.5 in. Register adjustment: +/-0.018 in. Bits per track (max.): 6144 pm recording Track width: 0.034 in. Tracks per inch: 20 Capacity (total): 276,480 bits Packing density (max.): 400 bits/in. at 4.7 in. dia. Rotational speed: 1200 or 1800 rpm Frequency (repetition rate): 184kc (max.) Recording surface: Proprietary plated cobalt Head spacing: Flying head Head inductance (typical): 1 mh/half coil Write current (typical): 28 ma Readback voltage (typical) 1200 rpm: 180 mv (min.), inner track 340 mv (max.), outer track Bearing life (average): 10 years The Model L-323 has the following characteristics: Power requirements: 115-volt, 60-cycle, single-phase AC Disc diameter: 10 in. Weight: 60 lbs. Axis of rotation: Vert., horiz., or any combination Recording diameters: 4.7 in. to 9.2 in. Number of tracks: 135 (15 groups of 9) Number of registers: 12 Register length: 0.25 or 0.5 in. Register adjustment: +/-0.018 in. Bits per track (max.): 6800 pm recording Track width: 0.034 in. Tracks per inch: 20 Capacity (total): 1,000,000 bits Packing density (max.): 400 bits/in. at 4.7 in. dia. Rotational speed: 1200 or 1800 rpm Frequency (repetition rate): 204kc (max.) Recording surface: Proprietary plated cobalt Head spacing: Flying head Head inductance (typical): 1 mh/half coil Write current (typical): 28 ma Readback voltage (typical) 1200 rpm: 180 mv (min.), inner track 340 mv (max.), outer track Bearing life (average): 10 years driven by one motor. My guess is that the L-321 (what I have) denotes the single platter device. So L-300 is probably the general series family, and L-321 and L-323 are the specific product models. -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]

Ethan> My anecdotal evidence is that the DF-32 disk is Omsmium Ethan> plated. I hope not, as I have four platters with, probably, Ethan> fatal levels of restarting, meaning that if I ever want to Ethan> return them to service, I'll have to either replace or replate Ethan> the platters. That would be expensive if true. But it doesn't make any sense. The plating has to be ferromagnetic. Nickel or cobalt are, but osmium is not. paul

Hi, Someone's selling tu58 carts (a.k.a. "dectape II") for a 730 on ebay. http://search.stores.ebay.com/search/search.dll?query=DEC&srchdesc=y&am… I snapped up the diag tape. There doesn't appear to be a boot tape. The other tapes I don't know about. For example, what's a "vax 11 hardcore" tape? (sounds like something I'd want to *watch* :-) Does that somehow turn on pdp-11 emulation? And is the "microdiag" tape useful? The cluster exercisor does not seem useful (I can't imagine a cluster of 730's :-) If anyone else buys these, please let me know - I'd like to scan them into disk files. -brad

On Fri, 26 Mar 2004, Jochen Kunz wrote: I've been in Karlsruhe two times yet. It is a real Z22 (not one of the newer Z22R), i.e. it has (had) the old style drum memory which often caused problems with signal amplitudes and head adjustments. The new style is sealed and has magnetic bearings. BTW the machine has the serial number 13. And of course it is still running perfectly. And please don't forget our LGP-30 here. It is still the only existing LGP-30 on earth in fully working condition (until proved otherwise) incl. high-speed reader/punch and software. I had posted a link to our papertape software collection some time ago. Christian Corti

Quothe Jochen Kunz, from writings of Tue, Mar 30, 2004 at 12:42:35PM +0200: Hmmm... then you haven't heard of Mel either? Speaking of such, does anyone on the list have an RPC-4000? -- Copyright (C) 2003 R. D. Davis The difference between humans & other animals: All Rights Reserved | My VAX | an unnatural belief that we're above Nature & www.rddavis.org | runs VMS & | her other creatures, using dogma to justify such 410-744-4900 | doesn't crash!| beliefs and to justify much human cruelty.

Paul Koning schrieb: Naturally, the story of Mel is true in every detail. Program we run on out LGP-30 are: ACT-V, an improved Version of Mel's ACT-I. We can play Moonlander, or print nice function-tables. (If you want to use the squareroot or sine- function in an ACT program you have to load this function on a free track on the drum. We have two programs to calculate the number PI. Ther are some versions of a floating point interpreter. Christian wrote a poem generating program. And last but not least: Black Jack. BTW: I just had a look to the link Al Kossow pointet to http://www.wps.com/projects/LGP-21/mel-the-programmer.html It shows the head of a coding sheet reffering to program 13.0. A look in our program library: We have the program 13.2 as paper tape. The programs had no names, they numbered them from 9 upwards, with a version number behind the decimalpoint. Klemens -- ---------------------------------------------- Klemens Krause Universitaet Stuttgart / Inst. f. Softwaretechnologie Universitaetsstr. 38 / 70569 Stuttgart Tel.: 0711/7816 341

On 30 Mar 2004 12:29:41 -0500 "R. D. Davis" <rdd(a)rddavis.org> wrote: Mel? As "Mel The Programmer"? Yes I remember Mel, but I didn't remember the name of the machine. -- tsch??, Jochen Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/