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mizapf

TI-99/8 emulation

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It was very fortunate that Ciro got a pretty "advanced" console; remember how many (of the few) TI-99/8 consoles are out there with missing speech, missing Pascal, or other defects.

 

I sent Ciro dump programs (written and tested with the emulation of the 99/8 in MESS at the previous maturity state) that were intended to save the GROM contents to disk. This worked quite well.

 

The problem was now that Pascal still did not work. In the schematics one can find a ROM (16 KiB) which is named "P-Code ROM" (aside from the GROMs). However, neither the specifications mention this ROM, nor does the schematic of "Mofetta" alias "Skunk", one of the custom chips on the board (the physical address mapper). That means I knew of that ROM, but not where it can be found in the 16 MiB address space.

 

With the recent dumps from Ciro I was able to find out the position; for that it was important to have a consistent set of ROMs from a working system. Then I used log outputs and the MESS debugger to find out where things start to go wrong.

 

I noticed that a new physical address was set in the mapper that was not used before or mentioned in the specs (f0xxxx), so I updated my dump tool to try to dump the 16 K starting at that address from Ciro's console. As it seems, we hit gold.

 

The next thing to be done for the TI-99/8 would be a Hexbus floppy emulation. This would be extremely helpful because the built-in Extended Basic II requires a Hexbus floppy.

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Very good job from Michael, thanks for his patience with me too :-) and my ti99/8 that done correct dumps :-)

 

This is my ti99/8 system... now emulated on MESS... it seems to be strange thinking my /8 is on my PC too :)

post-24673-138679074245_thumb.jpg

 

Edited by ti99userclub
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Wow! Yes that is seriously cool! Nice job to both of you. This is really a big thing IMO. Brilliant work!

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If you don't have access to them, I guess I should make some images of the UCSD Pascal V4.11 disks for the /8, since they are now useful to people other than me. . .

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It was very fortunate that Ciro got a pretty "advanced" console; remember how many (of the few) TI-99/8 consoles are out there with missing speech, missing Pascal, or other defects.

 

I sent Ciro dump programs (written and tested with the emulation of the 99/8 in MESS at the previous maturity state) that were intended to save the GROM contents to disk. This worked quite well.

 

The problem was now that Pascal still did not work. In the schematics one can find a ROM (16 KiB) which is named "P-Code ROM" (aside from the GROMs). However, neither the specifications mention this ROM, nor does the schematic of "Mofetta" alias "Skunk", one of the custom chips on the board (the physical address mapper). That means I knew of that ROM, but not where it can be found in the 16 MiB address space.

 

With the recent dumps from Ciro I was able to find out the position; for that it was important to have a consistent set of ROMs from a working system. Then I used log outputs and the MESS debugger to find out where things start to go wrong.

 

I noticed that a new physical address was set in the mapper that was not used before or mentioned in the specs (f0xxxx), so I updated my dump tool to try to dump the 16 K starting at that address from Ciro's console. As it seems, we hit gold.

 

The next thing to be done for the TI-99/8 would be a Hexbus floppy emulation. This would be extremely helpful because the built-in Extended Basic II requires a Hexbus floppy.

impressive stuff.

 

Could some of it be ported back to the ti-99/4a, for example Extended Basic II.

Do you know if the pascal version differs from the p-code card version for the PEB?

i mean would it be possible to build a p-code cartridge for the ti-99/4a of it?

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congrats! it was really good that Ciro won the 99/8 auction. and that michael is taking care of ti 99 emulation on m.e.s.s.

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I could be wrong-but I detect a complete lack of elitism amongst the TI community, That TI99/8 could easily have been won by somebody who simply wanted it to sit on a shelf and to hell with everyone else, it is nice to see the machine is being allowed to live on through a genuinely enthusiastic buyer.

 

I do feel a bit inadequate though-I have been collecting TI99/4a stuff for a while now and have only recently joined the PEB club!!!!!, there must be at least three of us now in the UK!

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Thank you guys, TI-99/8 was for me an "impossible" dream ... in true i had no money to purchase it, I asked for help on a financial loan in 36 months to buy / 8 ... I'm still paying it :roll:

... but at the same time I'm glad to see it at home with me ;-) ...

is also very nice to know that the emulation on the Mess is completing and this thank also to Michael who is another nice enthusiastic 99er ...

I like to think of all the 99ers guys as a community of the best old friends and I have often confirmed this impression on many occasions.(Ciro)

Edited by ti99userclub
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If you don't have access to them, I guess I should make some images of the UCSD Pascal V4.11 disks for the /8, since they are now useful to people other than me. . .

These would be extremely useful to me. Already found out the hard way in MESS that the TI-99/4 P-system disks won't work :-)

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Are there any plans to include 99/8 emulation into either Classic99 or JS99er? Some of that 62.5K memory could be very useful along with the 12MHz speed. Of course, the 1st thing I would do is make a conversion of my Castle Conquer game for it. :)

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We are very few to own a 99/8 computer, and among the owners, very few have the same configuration: 99/8 computers don't have the same onboard Basic and TI Extended Basic cartridge is not compatible (not compatible on mine) So a 99/8 conversion of your Castle Conquer game will be mainly played via an emulator and not on a real computer. A big lack of interest in my opinion. I think that if you want to add many levels on your game keeping the memory restiction of the 99/4A, you should manage the levels in disk files, so only some level would be loaded in the RAM at a time.

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We are very few to own a 99/8 computer, and among the owners, very few have the same configuration: 99/8 computers don't have the same onboard Basic and TI Extended Basic cartridge is not compatible (not compatible on mine) So a 99/8 conversion of your Castle Conquer game will be mainly played via an emulator and not on a real computer. A big lack of interest in my opinion. I think that if you want to add many levels on your game keeping the memory restiction of the 99/4A, you should manage the levels in disk files, so only some level would be loaded in the RAM at a time.

ok, so the extended basic that is built into the ti-99/8 ... that differs from machine to machine?

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The computer was in developpement stage and never really finished, and the built-in Basic was not finalized too. I saw some 99/8 computers that have "TI Extended Basic II" , my 99/8 has "TI-Basic v.1" (aka Armadillo Basic) but some Extended Basic commands work and some other don't or hang the computer. Too many differences between the 99/8 computers, too many instabilities to develop something with it.

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These would be extremely useful to me. Already found out the hard way in MESS that the TI-99/4 P-system disks won't work :-)

 

Please give me some details about your hard way. As you seem new to the forum, I'd like to tell you that I actively maintain the TI emulations in MAME (formerly MESS) and that I am happy to help whereever possible. I am, of course, depending on feedback and bug reports.

 

The TI-99/8 emulation in MAME is probably the most complete configuration that you can get among all real systems, with the exception of the still missing floppy drive support in Extended Basic II. The Pascal subsystem as well as many 99/4A cartridges proved to work. The Hexbus floppy is currently early work in progress.

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[...] with the exception of the still missing floppy drive support in Extended Basic II. [...]

 

maybe i do not understand, was not working the floppy drive ? i used that one and it is working on my /8

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maybe i do not understand, was not working the floppy drive ? i used that one and it is working on my /8

 

I referred to the missing Hexbus floppy support in MAME, which is needed for working in Extended Basic II. You have a (real) Hexbus floppy, if I remember correctly. We did our dumps in Editor/Assembler, anyway.

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I might have bought a P-Code bootdisk for the 99/8. I am not sure though.

I only tried to backup some of those 99/8/pascal development disks, but all of them were appearing as not readable. Either formatted for the myarc disk controller only or some other way.

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Please give me some details about your hard way. As you seem new to the forum, I'd like to tell you that I actively maintain the TI emulations in MAME (formerly MESS) and that I am happy to help whereever possible. I am, of course, depending on feedback and bug reports.

 

The TI-99/8 emulation in MAME is probably the most complete configuration that you can get among all real systems, with the exception of the still missing floppy drive support in Extended Basic II. The Pascal subsystem as well as many 99/4A cartridges proved to work. The Hexbus floppy is currently early work in progress.

 

To be precies: I tried using all the possible floppy controllers with the TI99/8, with the TI99/4 Pascal floppy images and with none of them, the P-system detected a disk in the drive at all. The images work fine with TI99/4. But I suppose this is the way things are supposed to be, and TI99/8 needs different floppies for the development environment. Or maybe I did something wrong, I'm not very experienced with MESS.

 

I don't have a TI99/8 nor ever had one but I'm interested in UCSD Pascal for various platforms. TI99/8 is especially interesting because the system had native support in BIOS for it.

(another computer I'm very interested in is SAGE, but emulation for that isn't nearly as far progressed).

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Frankly, I never tried to load UCSD Pascal disks for the TI-99/8 but only checked that the internal base system is running. But thanks to my floppy sound support, I hear that the floppy drive starts up, so it tries to load something. Eventually, it shows the main Pascal menu.

 

Do we have the Pascal disks somewhere?

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To be precies: I tried using all the possible floppy controllers with the TI99/8, with the TI99/4 Pascal floppy images and with none of them, the P-system detected a disk in the drive at all. The images work fine with TI99/4. But I suppose this is the way things are supposed to be, and TI99/8 needs different floppies for the development environment. Or maybe I did something wrong, I'm not very experienced with MESS.

 

I don't have a TI99/8 nor ever had one but I'm interested in UCSD Pascal for various platforms. TI99/8 is especially interesting because the system had native support in BIOS for it.

(another computer I'm very interested in is SAGE, but emulation for that isn't nearly as far progressed).

 

Keep in mind: We are talking here an unreleased computer (TI-99/8) depending on using unreleased hardware (Armadillo Bus interface for the 99/8 to the PEB or the Hex-Bus Disk Drive Controller) running unreleased software (P-System for the 99/8). You can hardly except Out-of-the-Box Functionality like for End-User Products, and I am talking about actually using the real TI-99/8 here. If you ask for proper emulation of all that, it requires a lot of undocumented things to be properly analyzed and later emulated and interacting with each other without any issues. If it would be easy, it would probably have been done by others before. MAME is the only emulator that runs the TI-99/8. There is no single emulator that emulates the Hex-Bus. The real PEB as such is not compatible with the 99/8, therefore the emulated PEB fails when it comes to Disk Access. The Memory Map is completely different compared to the 99/4(A), therefore the DSR fails.

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