On 2/13/2015 2:00 PM, Pontus wrote: I started one years ago and have been working on it very slowly as a background project. I used small, modern relays as they can be bought in quantity cheaply. I paid less than 5 cents each for mine. I've built memory out of the relays and have been toying with using a flip-dot type display board as a visual memory. A kind of mechanical graphical display. Some photos are here: http://www.dvq.com/oldcomp/relay/relay.htm Bob -- Dentopedalogy is the science of opening your mouth and putting your foot in it. I've been practising it for years. -Prince Philip

On 2/14/2015 8:23 AM, Liam Proven wrote: The Homebuilt cpus web ring is nice. Sadly I do not see many build-able computers that have any sort of DECIMAL arithmetic on them. Ben.

On 14/02/15 08:20, Brent Hilpert wrote: that website looks familiar, thats it, the memory core write up bookmarked and added to my wget queue :) I did bookmark and download electronixandmore website tom

Tom, any reason for choosing the Harvard architecture? I'm currently in the middle of a relay computer build so I'll toss in my 2 cents. The most important thing I hit on early is to define the instruction set, work out a number of potential applications/uses on paper (or excel), and step through each instruction to make sure the machine is capable enough. You'll probably discover a number of efficiency improvements you can make to the hardware while doing so, and a few "hardware subroutines" worth adding. You can also baseline how long a program will take to run if you settle on a clock rate, and determine if there's a better way to do it. Ultimately, relay computers are SLOW. Don't take 6 cycles to do what could be accomplished with a couple extra relays and a single pulse. Well thought out HW and instructions will pay big dividends when the soldering iron comes out. -Cory On Feb 13, 2015, at 5:52 PM, Brent Hilpert wrote:

Ben, I'm planning on 8-bit paper tape for I/O, but I was in touch with a gentleman from Brazil a few months ago that designed his architecture around 5-bit words. This allowed him to use the Baudot code and make use of teletype equipment that can still be found without too much difficulty. 8-bit ASR-33s are worth their weight in gold these days, but the 5-bit model 32 (or a 28 and tape peripherals) is much more reasonable. -C On Feb 13, 2015, at 7:14 PM, ben wrote:

Punched tape is about. Check out the "green keys" list, 5-level stuff comes up from time to time, generally at low cost. There is some ex-CNC items on E-Bay at present but for silly prices. Whilst I haven't seen any on E-Bay there were three Documation readers advertised on the Vintage Computer forums. slow) Many folks have implemented photo electric tape readers, but these tend to be clocked off the small feed holes. I guess it wouldn't be too hard to build a photo electric reader that has a 3-d printed feed wheel that was driven by a stepper motor. In fact I am pretty sure you could even use a coil and ratchet arrangement, like this one here:- http://grabcad.com/library/cam-operated-ratchet-pawl-1 but operated buy a coil and magnet rather than a rotating cam. Some one has actually made a complete but operated mechanical punch card computer.. http://observationdeck.io9.com/a-3-d-printed-hand-cranked-punch-card-compute r-1481921919 so I don't think its hard. Getting things 3-D printed isn't hard, in fact most FabLabs will have one and things can be printed for the cost of materials. Also Hack Space... I think it's the punch that's harder. You would need to harden the punch pins, and the would need to have a very exact fit. I guess a CNC router could be used to make these... Using a hand card punch isn't so slow once you get used to it, but these also seem expensive... Dave

On 2/14/2015 1:14 AM, ben wrote: error: many things

I suspect it is not "real machine work, but more likely honing and lapping. I see from the CREED-25 High Speed punch maintenance manual that the punch pins could need honing:- SHARPENING Of PUNCHES ==================== 4. 1 Remove the punches from the punch block as described in Section 7 of the Dismantling and Assembling Instructions. 4. 2 Insert the punches, individually, into a lapping block (TA.1301, supplied with the tool kit) so that the chamfered cutting edges of the punches are parallel with the chamfered side of the block. So perhaps it is not as hard to make these things in say a model engineering workshop. Dave

On 15/02/15 01:37, Peter Corlett wrote: also magnetic wire recording (1898) witch lead to magnetic tape recording in 1940 in my "What If" world the postal office network owned the telegraph network letters were delivered on punched card/tape to the post offices places that had mail/post rooms were asked to rent a mail computer THIS is that computer that I am concepting that why I asked about Magnetic tape filesystem and found phi-deck I thought about record sized floppy disk :) as I stepping stone I looked a normal floppy disk, but the are track based not spiral based, CDs would add to much extra hardware, so Magnetic tapes were the simpler option tom

On Sun, Feb 15, 2015 at 09:38:31AM +1000, Tom Sparks wrote: [...] In the UK, that was indeed the case. In a fine bit of legal wrangling, it was argued that the GPO's monopoly on the postal service extended to the other peer-to-peer communications systems such as the telegraph and telephone as they were invented. Had the GPO not had the telephone service rebranded BT and privatised in the 1980s, it would no doubt be claiming monopoly rights over Internet access as well. As it is, BT still pretty much control the market. [...] There were quite a few bizarre tape-loop systems for early microcomputers that were claimed to be random-access and cheaper than floppy disks, but were generally extremely unreliable, and I doubt they really worked out cheaper for anything but trivial storage needs due to there being only one manufacturer of the bespoke media. Sinclair's "microdrive" was perhaps the canonical unreliable storage. It takes a lot of effort to be more unreliable than a C90 cassette tape, but Sir Clive was well up to the challenge thanks to his ability to penny-pinch to the limit and then cut some more corners just to make sure.

ISTR a 2.9" floppy with a single spiral track