I sent you a direct message with an image of the cable I'm using. I refer to the cable I have as a "straight through" cable as the pins on the M100/M102 match the pins on the DVI. When I lay the DVI cable flat on the table with the M100/102 connector pins up (as it would be when installed in the M100/102), pin 1 on the M100/102 is pin 1 on the DVI. Pin 20 on the M100/102 is pin 20 on the DVI. And so on.
Jerry On Mon, Nov 18, 2024 at 10:55 PM Michael Brutman <[email protected]> wrote: > I know this is going to sound crazy but ... > > On the M102 system bus connector Pin 1 is marked on the top side of the > connector next to the reset button. That means pin 37 should also be on > the top row - second pin on the top row of the other side near the printer > port. > > If I probe a machine with a logic analyzer and press reset, pin 37 (RAM > RESET) does nothing. It's neither negative or positive. It is just dead. > But if I probe what appears to be pin 37, I get the expected behavior on > the reset button - logic low that then goes high while the button is being > held. > > The same thing is happening on pin 32 (RESET). If Pin 1 is marked > correctly then pin 32 should be on the bottom row, That pin is active and > constantly changing state, so it's clearly not reset. But pin 33 (INT REQ) > would have that behavior. Moving to what should be pin 31 (top row) shows > logic low normally and logic high when I hold the reset button. > > Is the IO Bus on my machine wired with the pins already reversed? > > > > > > On Mon, Nov 18, 2024 at 7:22 PM Jerry Davis <[email protected]> wrote: > >> Seems to be a cable/connector issue. >> >> I repeated the sequence you described on the M100 and DVI that I have >> here and BASIC loads and starts as expected. >> >> I have a ribbon cable with a broken signal pin at the M100 end and my >> M100 does what yours does when I use that cable. Which makes me think you >> may have a cable problem. >> >> Jerry >> >> On Mon, Nov 18, 2024, 7:20 PM Michael Brutman <[email protected]> >> wrote: >> >>> I powered on the M102 first, then the DVI. After the copyright message >>> came up I tried the reset button, power off and then power on, and a cold >>> start. The machine restarted but the amount of free memory remained the >>> same and the DVI disk light did not turn on. I'm fairly certain the DVI is >>> not seeing the reset signal from the M102. >>> >>> Going to BASIC and using SCREEN 1,1 fails because I'm still on the >>> built-in BASIC at this point, as DISK BASIC never got moved into the memory >>> on the M102. >>> >>> >>> -Mike >>> >>> >>> On Mon, Nov 18, 2024 at 3:20 PM Jerry Davis <[email protected]> wrote: >>> >>>> After executing the power-on sequence and getting the "Microsoft" >>>> message, did you execute the BASIC command "SCREEN 1,1" from the Model 102? >>>> >>>> The above command switches output to the CRT on the DVI and displays >>>> the key labels at the bottom of the CRT. >>>> >>>> Jerry >>>> >>>> >>>> >>>> On Mon, Nov 18, 2024 at 11:39 AM Michael Brutman <[email protected]> >>>> wrote: >>>> >>>>> I've tried all three methods - power off/power on, Reset, and cold >>>>> start. There is no difference. Also, the two machines have no options or >>>>> expansions that would alter their behavior. >>>>> >>>>> The technical service manual has a reasonable troubleshooting guide >>>>> which gives specific pins and behaviors to look at. I'd still like to >>>>> find >>>>> a known good cable before breaking out an oscilloscope, but at least the >>>>> schematics and behaviors are documented. >>>>> >>>>> The length of the cable is kind of freaking me out a little bit - for >>>>> a bus that's a long stretch. Do you know the length of the original >>>>> factory cable? >>>>> >>>>> >>>>> -Mike >>>>> >>>>> >>>>> On Mon, Nov 18, 2024 at 9:19 AM Royce Taft <[email protected]> >>>>> wrote: >>>>> >>>>>> One other thing you could try is a cold start (CTRL+PAUSE+RESET). It >>>>>> will wipe all your 102’s memory, but maybe it will help? >>>>>> >>>>>> Royce >>>>>> >>>>>> Sent from my iPhone >>>>>> >>>>>> On Nov 18, 2024, at 08:34, Michael Brutman <[email protected]> >>>>>> wrote: >>>>>> >>>>>> >>>>>> I had checked the connectors and pins before I wrote, and I was even >>>>>> going to check for continuity on each pin but that's going to take a >>>>>> while >>>>>> and be error prone with 40 pins. The connector on the underside of the >>>>>> DVI >>>>>> has the snap-in latches which are engaging. I can't push any further >>>>>> and I >>>>>> haven't bent any pins. The cable is new from Gregory (Arcade Shopper), >>>>>> so >>>>>> I don't have a lot of reason to suspect it. >>>>>> >>>>>> Besides trying two different 102s I've also tried batteries and wall >>>>>> power for the 102s, and I even upgraded one to max out the RAM just in >>>>>> case >>>>>> I was missing a memory requirement. >>>>>> >>>>>> The DVI unit itself was pristine on the inside when I first looked at >>>>>> it. I'll have another peek inside to check the connector; perhaps it >>>>>> experienced some trauma and there are broken traces on it. But I really >>>>>> don't want to look for problems where they are unlikely or fix things >>>>>> that >>>>>> are not broken .. I've learned that every time I disturb something there >>>>>> is risk involved. >>>>>> >>>>>> Is there anybody in the Seattle area (northern suburbs) with a known >>>>>> good cable? If I can eliminate the cable as a possibility then there is >>>>>> only the DVI connector, as the rest of it seems to function normally. >>>>>> >>>>>> >>>>>> -Mike >>>>>> >>>>>> >>>>>> On Mon, Nov 18, 2024 at 7:10 AM Royce Taft <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> When I had this issue, it turns out I hadn’t snapped the connector >>>>>>> in fully on the underside of my M100. I would disconnect it and ensure >>>>>>> no >>>>>>> pins became bent and flattened out. If the pins look good, carefully >>>>>>> replace the connector and snap it firmly into place. >>>>>>> >>>>>>> When making my cable, to figure out the location of pin 1 on the >>>>>>> M100 and the DVI, I think I used a multimeter and the pin outs in the >>>>>>> various manuals to look for ground pins which gave some insight into the >>>>>>> orientation of the connectors. >>>>>>> >>>>>>> Seeing “please wait” followed by a Microsoft copyright is a very >>>>>>> good sign that your boot disk was successfully read. >>>>>>> >>>>>>> Royce >>>>>>> >>>>>>> Sent from my iPhone >>>>>>> >>>>>>> > On Nov 17, 2024, at 21:20, Michael Brutman <[email protected]> >>>>>>> wrote: >>>>>>> > >>>>>>> > >>>>>>> > Ok, here is the part I hate ... getting things put together and >>>>>>> then not having it work. >>>>>>> > >>>>>>> > I'm using Greg's cable kit with a Tandy 102. I have the twist >>>>>>> adapter on the 102 side, red stripe oriented as in the pictures on the >>>>>>> Wiki. (The red stripe closer to the 'S' of "System bus".) That goes >>>>>>> into >>>>>>> the IDE ribbon cable, which is connected to the DVI also using the >>>>>>> orientation in the pictures from the Wiki. >>>>>>> > >>>>>>> > I used Teledisk to create the disk image. I powered on the 102 >>>>>>> first, as per the DVI user manual. When I power on the DVI I get the >>>>>>> "Please wait!" message, and then I get the Microsoft copyright message. >>>>>>> All of this is good so far. >>>>>>> > >>>>>>> > Where things fail is when I try to load disk BASIC onto the 102. >>>>>>> The instructions say to use the Reset button or to power the machine on >>>>>>> and >>>>>>> off. Neither has any effect, and I've tried it with two different 102s. >>>>>>> > >>>>>>> > What am I missing here? >>>>>>> > >>>>>>> >>>>>>
