Curiosity killed the . . . I just removed the ECU from my bike. The Yamaha part label on the casing says 4BH-8591A-00 (UK-spec). The small Toshiba logic chips (IC602, 306, 304, 305, 603) and the larger Hitachi chips (IC302, 303) are the same as the illustrations on www.gts1000.org. Incidentally the number suffixed H on the Toshiba chips is almost certainly a date code: 9237 would be 37th week of 1992. One Hitachi chip is a programmable timer HD63B40P CMOS PTM (programmable timer module) with 2.0 MHz clock frequency. The other is a HD63B21P 2MHz CMOS peripheral interface adapter (PIA). If anyone has a subscription to chipdocs.com or similar, they could get more information about these devices. Listers with an interest in electronics might want to look at http://www.mqp.com/ad554.htm - it shows a programmer adaptor for a Hitachi device in a 40-pin package; said device looks like an MCU (i.e. processor plus memory in one chip). Not that this is the same device as the Hitachi ones in the ECU, though! The code on the ND chips is different on my bike to the website photos; IC301 is marked MG1730/9M14 and IC701 is marked MH614/8M20. If the Hitachi device is not an MCU, then perhaps one of the ND devices is a One-Time Programmable MCU, and perhaps the different codes mean different programs for the various specs (UK, US, '93, '94) ?? I know nothing about IC781 (the upright device in a cage, picture 8; it has a "window" like an EPROM, but it also unquestionably has an air-hole, which favours the explanation than it is an atmospheric pressure sensor. Anyway, as someone else pointed out, there doesn't seem to be any feasible way to re-program, and FWIW, I've never experienced the "surging" problem on my UK-spec bike. David Thurgate http://www.uranus.co.uk/M_cycles.htm =================================================== Kawasaki ZX750-A1 in Tony Foale FFE frame Current status: Dismantled ;-( Yamaha GTS1000a in Yamaha FFE frame Current status: In everyday use :-)
