2016-09-22 22:24 GMT+02:00 Pete Lancashire <[email protected]>:
> I would start looking at the Display DACs (Vol 2 p 2-10, and 2-11) Each > DAC consists of a 6820 PIA, then LS TTL Latches, diodes, and discrete & dip > resistor arrays. Then an OP Amp. to do the summing. Today it would all be > one IC. > > In character mode these two DACs set the base position of each character, > > Bring the cursor up to the top left and as you type look at the output of > the X DAC it should be a staircase, Do the same with the Return key, and > watch the Y DAC. > > The Bottom of 2-11 are the DACs that are the dot positions for each > character. > Good idea. I will do this as soon as I replaced the TIP50. Well. Of course this could be done without working display but it would be hard to understand what is going on. Unfortunately measuring on the D/A and the filter takes that the main board is pulled out and setup to operate outside the machine. > > Vol 1 pages 6-19, 20 , 21 and 22 describe how the DACs work > > Manuals are on bitsavers > > http://bitsavers.informatik.uni-stuttgart.de/pdf/tektronix/405x/ > > > > > > > > On Thu, Sep 22, 2016 at 12:19 PM, jim stephens <[email protected]> wrote: > > > > > > > On 9/22/2016 12:08 PM, Charles Anthony wrote: > > > >> > >>> Before the smoke escaped I recorded this short videoclip to show the > >>> behavior when typing on the machine and running simple PRINT/GOTO > >>> program. > >>> > >>> http://sendvid.com/k4s7k806 > >>> > >>> This link took me a fake virus warning honey trap. > >>> > >> -- Charles > >> > >> > >> Sendvid may be a honeytrap, but in lynx on linux, where i usually test > > such, it went to sendvid and sent two cookies. Probably safe. > > > > >
