Somebody who knows more can correct me, but I don't see any reason Pin 10 would be intentionally bent under. According to the datasheet, it is address line zero, *A₀*, so the ROM would still be putting data on the bus, it just would be choosing an even or odd address arbitrarily. On the other hand, when I see pins bent through carelessness, it is usually at the corners, not in the middle. Also, you said it looked like nobody had mucked about inside before. Perhaps it was a fault at the factory and this machine has never been able to run MSPLAN before?
[image: image.png] ---b9 On Wed, Aug 7, 2024 at 12:02 PM B 9 <[email protected]> wrote: > Great job fixing MSPLAN! I have never heard of a reason for the pin to be > bent under. All I can think is that perhaps this machine used to be > attached to something over the System Bus connector and the ROM had to be > disabled to not interfere. > > For the missing RAM, you may already know this, but one of the interesting > things about the Tandy 200 is that it doesn’t differentiate between storage > and memory. So, if you save a file that is 1,466 bytes, your working RAM > will be reduced by the same amount. Try hitting F1 from the MENU to > switch to a different bank of 24K and see if that changes things. > > … wait a minute! > > Actually, now that I’m writing it, I am realizing that you said HIMEM was > reduced, so forget what I said about files. HIMEM marks the start of the > portion of memory which is off-limits to BASIC and it can be changed with > the CLEAR command. This is useful to stash machine language programs, > such as AsciiPixels > <http://club100.org/memfiles/index.php?direction=0&order=&directory=Ken%20Pettit/AsciiPixels>. > To reset BASIC back to using the maximum amount of RAM you can do this: > > CLEAR 256, MAXRAM > > —b9 > > On Wed, Aug 7, 2024 at 9:37 AM Tom Blum <[email protected]> wrote: > >> I'm having fun now. And success getting MSPlan running. Plus a new >> mystery. >> >> A close inspection of the T200 insides found the following: >> >> 1. Light corrosion on the negative terminal of the backup battery; will >> replace that as soon as the new NiMH battery arrives >> 2. a bit of the coating on thermistor TH2 chipped away, component still >> functioning (see below) >> 3. no signs of leaking capacitors or fluid/liquid intrusion >> 4. no signs of degradation or consequential damage to traces >> 5. on the bottom of the main PCB, some surface mounted components with >> discoloration around the mounting pads and on parts of the components: >> R185, M30, M32, T17-T19 in particular (see below). All of my vintage >> computer experience has been with Ohio Scientific boards manufactured >> before 1980 and not involving components at these small scales. I can't >> tell if the discoloration is due to excess flux or some sort of discharge. >> Whatever the cause, the system is functioning. I'm certain I don't have >> the skill/steady hands to work with components on this scale. >> 6. No sign that anyone previously mucked around inside the system >> >> 7. The MSPlan ROM (M14) was installed with pin 10 bent all the way under >> the IC. Before reseating the ROM, I bent the pin back out. >> >> Once the M14 ROM was reseated and the unit reassembled, MSPlan launched >> just as it should. And all other ROM-based applications launch as they >> should. BUT.... >> *New mystery*: the system now reports in BASIC 17,868 bytes free -- >> that is 1,466 bytes fewer than should be the case. HIMEM is also reduced >> by 1,466 bytes. >> >> Now I am wondering if pin 10 was supposed to be left bent under and the >> ROM just needed to be reseated. Exactly how that would relate to the >> availability or non-availability of 1,466 bytes I don't know. >> >> Tom >> >> >> >> On Tue, Aug 6, 2024 at 9:40 PM B 9 <[email protected]> wrote: >> >>> Brian is right that whatever happened to make tge builtin ROM disappear >>> is pretty serious. Birt has some good videos >>> <https://www.youtube.com/watch?v=1adlQo3UI90> on fixing up such >>> problems on his YouTube channel <https://www.youtube.com/@HeyBirt>. >>> Even if you don't have the time right now to completely fix it, it would be >>> good to open it and clean up any corrosion. >>> >>> One last thing to try, although I'm pretty sure it will be exactly like >>> running it from the menu: On my Tandy 200 you can launch MSPLAN from BASIC >>> by using `CALL 61167, 1`. What does it do on yours? >>> >>> —b9 >>> >>> On Tue, Aug 6, 2024 at 8:00 AM Brian K. White <[email protected]> >>> wrote: >>> >>>> I can only confirm that MSPLAN works with no option rom installed. >>>> >>>> Could be either bad ram or bad rom. There are two rom chips inside >>>> besides the option rom socket outside. Or anything else like a corroded >>>> trace making a stuck address line. These units all have leaking caps >>>> and >>>> batteries by now, even if they are still working. >>>> >>>> Don't be loath to open it, run to open it to arrest the development >>>> from >>>> getting worse as soon as possible. >>>> >>>> -- >>>> bkw >>>> >>>> >>>> On 8/5/24 09:51, B 9 wrote: >>>> > That's actually pretty cool and I'm curious what GTE's firmware does. >>>> > What software version are you seeing? >>>> > >>>> > I'm not sure why they would overwrite MSPLAN yet leave it in the >>>> menu, >>>> > but if they added an "option ROM", I believe you can run it with >>>> `CALL >>>> > 61167, 2`. >>>> > >>>> > —b9 >>>> > >>>> > >>>> > On Sun, Aug 4, 2024 at 6:10 PM Tom Blum <[email protected] >>>> > <mailto:[email protected]>> wrote: >>>> > >>>> > Hello, >>>> > >>>> > New to the community and apologies if I'm raising a question/issue >>>> > already addressed. Just purchased a working T200. Power cycles >>>> > nominally and shows classic menu options. Selecting Multiplan >>>> from >>>> > the menu places the T200 into a frozen state. LCD screen appears >>>> to >>>> > fill (shaded) completely but program does not start, no visible >>>> > text/graphics. Resetting and power-cycle necessary to get back >>>> to >>>> > the main T200 menu. Noted that this T200 has a property label on >>>> > the bottom indicating that GTE, Inc. (the telecom company) was a >>>> > previous owner and appears to show a unique GTE software version >>>> #. >>>> > Is it possible that the original/built-in Multiplan ROM was (or >>>> > could be) removed from the T200. As a newbie to the T, am loathe >>>> to >>>> > open up a working unit to see if a ROM is missing. Is there a >>>> past >>>> > or present ROM option module for the T200 that would have >>>> Multiplan >>>> > installed (or installable)? Tom >>>> > >>>> >>>> -- >>>> bkw >>>> >>>>
