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Recent content by DaveH

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    Midwest 6800

    Hi, I have an MSI 6800 in storage, lookes the same as yours but in much worse condition, I have a listing of MSI-BUG MT-1 and when I get my scanner to work I can scan it if this is any help. I should have more documentation but will have to dig it out. Dave
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    New, to me DEC PDP8E

    When testing diodes in circuit I use the diode test function on my multimeter as it uses a voltage high enough to forward bias a silicon diode , a resistance test may not work as the voltage is often not high enough, I just look for a difference in the reading between testing the diode in both...
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    Who wants to help me with a little experiment? (and some street cred!)

    My old BT modem would do it, unfortunately its not been used for 30 odd years and I dont have time right now to work on it, maybe sometime later, teletype to teletype :)
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    Renovating my 6809 Flex system

    Hi all, and apologies Random fore not replying to your post, if I find any BBs I will let you know. Only been able to work on the system sporadically over the last few weeks but we are now basically all up and running after the following work. Got ready to debug the display card, card in...
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    Renovating my 6809 Flex system

    Hi, sorry for the gap in postings, lots of "unimportant" stuff ( vat return, year end, client computers/systems/software ) getting in the way. Well after getting the display card to work I looked at the green screen monitor, careful power up resulted in a faint but correct sized raster but no...
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    Renovating my 6809 Flex system

    Thanks Marty, we are getting there slowly, Im not really a very fast worker, I have a tendency to get sidetracked. Working on something like this is MUCH easier than an 11, ive not yet got anywhere with my 11/50. Got both display cards working , faulty bus buffer in the first and a dud LS04...
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    Renovating my 6809 Flex system

    Hi Random, So you got your system up and running , nice one, I remember 2102's, 1k by 1 I seem to recall, took 64 to make an 8k byte card, and lots of 5 volts. :) Hi Woodchips, I don't remember my system being particularly slow, mind you I did not have much to compare it against, only the...
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    Renovating my 6809 Flex system

    During the 1980's my job involved embedded control using the Motorola 6800 and 6809 series microprocessors so when I managed to buy two 8" disk drives at an affordable ( just ) price I was able to design and build my own 6809 based system. This has lain untouched for about 25 years until...
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    MEK6800D1 with 8K RAM, Cassette Interface, and Bit Boffer

    Oh Bother, there goes tonights project :) ( trying to transfer binary files to my PDP8/m under os8 ), have "dug out " the 6809 sys, will have to give it a cleanup and checkout before trying a power up . Dave
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    Things to do with a PDP8 No.1242, Decode Morse code.

    http://youtu.be/V0LCFHeUZfo Although I passed the Radio Amatur theory exam in 1965 I never actually got my licence ( ticket) as I did not manage the then obligatory, for the UK, 12 word per minuet Morse. Listening to the ham band for the first time in 45 years or so I found that my ears...
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    The pre-history of the Digital Equipment Corporation

    I found this during a coffee break brows and thought it might be of interest to other forum members. http://www.cs.man.ac.uk/CCS/res/res04.htm Dave H
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    Hardware handshake on a M8655

    Wanting to transfer reasonable sized text files from my PC to the Lab8 recently and not having one of Philipp,s "magic" USB cards I wandered how hard it would be to add RTS/CTS hand shaking to a M8655. Turns out quite easy. There is already a driver in place, part of E50 , op on pin 6 to...
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    Debugging an RX01/RX02 on an RX8E in a PDP-8/e

    Personally I find repairing boards stimulating and very satisfying and would add lots of coffee to the "tools" needed :) so far the only ones that have defeated my are actual failed core stacks. I do have quite a few ;) Dave
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    Substituting for the DEC 384 and DEC 6380 IC's

    I was recently asked to expand about a passing reference I made to a small PCB I use to substitute for the above IC's. The 6380 is a quad 2 input NOR and the 384 a quad 2 input OR , both are fairly extensively used on Omnibus boards, especially the 6380 as a bus receiver, both are...
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    Unibus Interface ICs

    Hi, no there is an offset, 0.15 " dave H
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