I do suspect this was an error at the time of manufacture. Since the T200 with the bent ROM pin still powered up and showed the normal menu options and RAM, a simple QA process could have let it slip.
After powering down and resetting, the RAM available is according to spec. Many thanks for your help, ed, Aug 7, 2024 at 3:23 PM B 9 <[email protected]> wrote: > 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 >>>>> >>>>>
