Date: Fri, 2 Aug 1996 23:17:47 -0700 To: tghack-list@cpac.washington.edu From: Joe LoCicero X-Software: MLF v2.3, Copyright 1995, 1996 by Bt X-Original-Id: <199608030618.CAA03796@jaguar.ece.cmu.edu> Subject: New TG Bus pinout diagram Never let it be said that I never do anything for the list. :) I finally completed my trace of the "expansion bus" on the PC Engine. Note that some of these pinouts aren't immediately useful; we still need to figure out exactly what the chips that they're connected to DO. :) Configure your reader or text editor to view this diagram with a monospaced font, otherwise it probably won't align correctly. It's a 69 pin connector, 3 rows of 23 pins each. Diagram from the back of the PC Engine/TurboGrafx, right side up: AR GG 01 VM 32 30 27 GG 17 20 22 23 13 11 10 08 GG 05 03 GG VV VN VR 02 CD 35 34 VU 29 26 15 19 21 VJ 14 12 VG 09 07 06 04 24 VT 37 36 VP AL VV VS 33 31 28 25 16 VL VK QQ VI VH QQ VF VE VD VC VB VA GG VZ VQ Explanation of the codes: ## -- HuCard pinout of that number. These are numbered 1-38 from right to left, from the front of the unit. The following pins are represented: 1-17, 19-37. (18 is ground, while 38 is +5V, so technically all 38 pins come out on the expansion bus.) AR -- Audio Right AL -- Audio Left VZ -- External composite video, connected to R145. Note -- this may need to be externally bypassed to ground with a capacitor to use directly as a video feed. VV -- +5V, regulated GG -- Ground CD -- CD 'sense' line. PCE: 6280 P30 CD: shorted to ground QQ -- External voltage input. PCE: 7805 P1 CD: supplies +5V VA -- 6270 P38 and 6260 P62 VB -- 6270 P37 and 6260 P63 VC -- 6270 P36 and 6260 P64 VD -- 6270 P35 and 6260 P65 VE -- 6270 P34 and 6260 P66 VF -- 6270 P31 and 6260 P67 VG -- 6270 P30 and 6260 P68 VH -- 6270 P29 and 6260 P69 VI -- 6270 P28 and 6260 P70 VJ -- 6270 P26 and 6260 P71 VK -- 6270 P25 and 6260 P72 VL -- 6270 P23 and 6260 P73 VM -- 6280 P59 and 6260 P79 VN -- 6260 P44 VP -- 6260 P47 VQ -- 6260 P49 VR -- 6260 P51 VS -- 6260 P61 VT -- 6270 P77 VU -- 6280 P45 The last set of abbreviations start with "V" because they mainly connect directly to the video chips. VU is the exception. Note that VA through VL seem to be a 12-bit data-bus between the 6260 and the 6270. This implies to me that the 6260 is also involved in video production; how exactly I have yet to determine. Remember that the 6280 is the main processor that runs the games; the other 2 are video coprocessors. I hope this helps some of you out! At least those of you without boosters/CD units will be able to connect up external stereo connectors to your machines...and perhaps a video connector too! And if anyone's feeling like playing with hardware lines, this is the best you can do without opening the unit itself. Good luck, Joe --- - Joseph LoCicero, IV jolo@ece.cmu.edu http://joyce.eng.yale.edu/~jolo - - A supporter of Inet Free Speech, OS/2, OpenDoc, and Cadence CAD tools - - The freedom of a society is proportional to how much its people laugh. - - - Zero Mostel -