Are BAD M100 A16 & BAD M100 A17 correctly titled on the screenshots? The sawtooth will be caused by the multiplex nature of the bus from AD0-AD7.
The stuck condition of the lines could just be that the CPU never gets out of a certain address range so the lines appear never to move. Or it could be the 80C85 (M19) is indeed bad or the H244 (M21) is possibly bad causing the inputs to be stuck high. The bad Address lines go straight into M21 based on the schematic. On the bad M100 the pattern repeats ~53ms so that is about 10,000 instructions (if my math is right) so I would expect all the Address/Data lines to at least toggle. It looks like M19 is bad. Any other lines appear to be stuck? From: M100 <[email protected]<mailto:[email protected]>> on behalf of Brian White <[email protected]<mailto:[email protected]>> Reply-To: <[email protected]<mailto:[email protected]>> Date: Monday, December 18, 2017 at 5:18 AM To: <[email protected]<mailto:[email protected]>> Subject: Re: [M100] diagnose Last night I did a little more poking. First, I looked at all the data lines at the cpu on a good M100, and verified that on a good M100, all of those pins show continuous streams of data while the machine is on. Then on the bad M100 I saw 2 differences from the good M100. 1) I can't get a stable trigger lock on any of the A* & AD* pins on the good M100. IE, On the good machine the data doesn't repeat exactly around 53ms like it does on most pins on the bad M100. 2) 4 pins are stuck high: A10, A12, A13, A14 Screenshots of pins AD0-AD7 & A8-A16 https://photos.app.goo.gl/vcTg4yUhvjXKBxeh1<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fphotos.app.goo.gl%2FvcTg4yUhvjXKBxeh1&data=02%7C01%7C%7Cb95f328a00c443cac69c08d54619c7f7%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636491998893045761&sdata=qHGx%2FKPE7hDkQojuMyGp6OFiuUvW89G5pRICZlOrfdE%3D&reserved=0> I thought those ramps and 2-volt sawtooths on the AD0-AD7 lines looked bad, but the good machine has the same thing. -- bkw On Fri, Dec 15, 2017 at 7:52 AM, <[email protected]<mailto:[email protected]>> wrote: I have a really basic one like this, based on the Cypress CY7C68013A https://sigrok.org/wiki/Lcsoft_Mini_Board<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsigrok.org%2Fwiki%2FLcsoft_Mini_Board&data=02%7C01%7C%7Cb95f328a00c443cac69c08d54619c7f7%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636491998893045761&sdata=pKKoy6jhKELmp2gu%2FA46lG45dgQ0OEfiZz4kKEBS5dY%3D&reserved=0> I like to use it with the saleae software, but to have 16ch instead of 8 I use Sigrok. Mauro Il 15.12.2017 12:56 Brian White ha scritto: On Dec 15, 2017 6:16 AM, <[email protected]<mailto:[email protected]>> wrote: BTW: Brian do you have a LA so we can compare the same signals on the ROM and RAM addressing/enabling on the working and not working Sorry I am looking at them but hadn't picked one yet. -- bkw Con Mobile Open 7 GB a 9 euro/4 sett navighi veloce con 7 GB di Internet e hai 200 minuti ed SMS a 12 cent. Passa a Tiscali Mobile! http://tisca.li/OPEN7GBFirma<https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Ftisca.li%2FOPEN7GBFirma&data=02%7C01%7C%7Cb95f328a00c443cac69c08d54619c7f7%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636491998893045761&sdata=pKP2eU7zzR1lsWJGBn7kyII9mInd%2FrunF9Q%2FIrzWO1A%3D&reserved=0>
