In <3E5AEAD9.4000807@telus.spamless.net> Wayne Stewart wrote: > I?ve seen boards with 40 pin headers like the one on the > TransWarpGS marked on the board with any of these numbering > schemes. Any opinions as to which is preferable in this case? > > > 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 > > 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 > > > > > > 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 > > 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 > > > > > > 39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 > > 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 > Is this for the cable which goes from the TransWarpGS to the CPU socket? The first pin header numbering scheme would give the correct pin numbers for the CPU socket plug. The last one is the standard used by IDC (insulation displacement connectors/ribbon cable). Numbering this way means pin 1 connects to wire 1, pin 2 to wire 2 etc. but then it won't match the CPU socket. -- Roger Johnstone, Invercargill, New Zealand Apple II - FutureCop:LAPD - iMac Game Wizard http://homepages.ihug.co.nz/~rojaws/ ________________________________________________________________________ No Silicon Heaven? Preposterous! Where would all the calculators go? Kryten, from the Red Dwarf episode "The Last Day" [posted and mailed] Wayne Stewart wrote in news:3E5AEAD9.4000807@telus.spamless.net: > I’ve seen boards with 40 pin headers like the one on the > TransWarpGS marked on the board with any of these numbering > schemes. Any opinions as to which is preferable in this case? > > > 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 > > 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 If it connects to the CPU slot this numbering is more appropriate... it matches the ordering system of the expansion slots and as used on most integrated circuits including the W65C816. Marsha In article <3E5AEAD9.4000807@telus.spamless.net>, Wayne Stewart writes: >I’ve seen boards with 40 pin headers like the one on the >TransWarpGS marked on the board with any of these numbering >schemes. Any opinions as to which is preferable in this case? > > >20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 > >21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 This is standard DIP-package IC pin numbering. > > > >20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 > >40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 This is the way many 2-row pin-and-socket connectors order pins. > > > >39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 > >40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 This is standard IDC connector ordering, derived from the ordering of the wires in the flat cable. If you have a cable with two different _kinds_ of connectors on each end, then something has to give. ;-) You can pick the most "significant" ordering and force it on the cable and the other connector, or you can keep each connector with its "natural" order, and then force someone reading the schematic/PC board to "decode" one scheme into another. I prefer the first approach for my own sanity, but I find that the second approach--with wires numbered differently on different ends of a cable--to be quite common. (Perhaps the reason is that connectors and standard layout templates usually have standard pin numbers on them, without regard to what they connect to, of course.) -michael Check out amazing quality 8-bit Apple sound on my Home page: http://members.aol.com/MJMahon/ Wayne Stewart (waynes@telus.spamless.net) writes, in part: >>"All the pins on the CPU socket are numbered so looking at the TransWarpGS header, the pins correspond with following CPU pin numbers 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40"<< Wayne, thx very much for the information. Just to be sure, though, does the pinout you've given convey that the first pin on the left, top row of the TWGS header corresponds to Pin 20 of the mainboard CPU socket....and the last pin on the right, bottom row of the TWGS header corresponds to Pin 40 of the mainboard CPU socket? John P.