AFAIK, KiCAD is comparable to Eagle on quirkiness of use, bugs, and support; but then, it looks better, and isn't limited in size (I know someone who built essentially a computer motherboard with it).
I'd definitely recommend it to newbies!
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
Lasse Langwadt Christensen wrote on 6/15/2017 1:56 PM:
Yes, you are right. I just use software that is from the 21st century.
-- Rick C
I do have some holes, copper plane keep-outs, in the ground and power planes. That's to reduce the capacitance on some timing-critical nodes. FR4 makes a horrible capacitor.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I don't save the Gerbers to floppy disks any more, so I don't care how big the files are. A fancy BGA power pour on a VME module might be
7000 lines of text in the Gerber file.
We've sold a lot of boards done with PADS. It's been good to us.
PADS-Logic is the best schematic editor that I've ever used. PowerPCB layout is reliable and works fine.
I did the design, schematic entry, and layout on one laser driver in a weekend. It's a small board, so all the Gerber files add up to 700K bytes. A big board might run 6 or 8 megabytes.
There's some other new single-file format, non-Gerber, that we've done a couple of times. I guess we'll cut over to that eventually.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Your HP 9100 has a ROM made of an array of PCB caps.
Nearly. The HP9100 PCB ROM was inductive, not capacitive. The traces marked out little transformers with ones/zeros dictated by current flow direction.
piglet
I see. Unfortunately the schematics online (hand-drawn pdf's) don't include the ROM or the registers or a number of other things.
This is fun reading ...
piglet
In one of those articles the designer of the 9100 says the sense amps for the ROM were made of 3 transistors. That must mean per bit, and it had a 44 bit VLIW. John says his units have about 150 transistors each. I had wondered about the 44 JK flops, since I thoght they needed 4 transistors but maybe just 2. Then there are also 3 data registers, and all 3 were on the display simultaneously so they needed some kind of selection and a 7-segment decoder (the CRT used a 7-segment "font"). The online schematics show the keyboard encoder, which uses mostly diodes and few transistors. It doesn't show the ROM or address decoder. I don't see how the addressing could use only a few transistors. Not to mention the ALU. The total count remains a puzzle to me. Even with the use of mostly diode logic it would take over 1000 diodes and seemingly much more than 150 transistors.
The ROM was 64 bit wide by 512. So there were 3*64 transistors in the row sense amps alone (32 each side of the array). Not sure how the ROM column drivers were arranged. There are not 512 for sure. I think the columns are grouped by fours and further muxed - drive current can be switched in several places after all.
He estimates 1800 diodes, 750 transistors and 2000 resistors. Perhaps the figure of 150 you saw is a typo for 750?
piglet
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