retroclouds

Today it’s time for giving an update and clarify where I see this project is heading too, as well as some things I’ve learned along the way. When I started thinking about what I want to accomplish with the editor, I knew this was a project that could easily span several years. The fact that it’s completely written in assembly opens up a lot of possibilities, but also means that development is rather slow, when compared to writing in a high-level language. So what is the plan and what is next. Accomplished so far: Loading a large DV80 file into SAMS works really well. The file I/O routines I have implemented go along with the stock disk controller, TIPI and HDR ramdisk nicely. Although loading large files is pretty slow, I am going to keep the file routines I have there and call this “compatibility” mode. I’ll also work on a new set of file I/O that’ll be a lot faster, but probably not as “compatible” with all type of disk devices out there. So far I’m really pleased with how fast working with large files on the TI-99/4a works. There’s still room for speed optimisation, but you know the saying: premature optimisation is the root of all evil. Along the way I did quite a few changes on how a DV80 file is stored in memory. Obviously storing the file as you would in VDP memory is not going to cut it, once your file contains a few thousand lines of text. Insert and delete speed is good, even for files with for example 5000+ of lines. As said memory organisation is very important for good performance. Implementing undo shouldn’t be too hard to do with the code I have in place now. Basically I have copy-on-write, so the old lines of text are still there in memory (at least to a certain extent) I threw out the 32K code. Mixing 32K and SAMS memory layout was a stupid thing to do. I’d rather create a 32k standalone version instead of mixing the two. Had a hard time fighting feature creep. I mean, this is about having fun and not only doing work. Nonetheless, the goal is to come up with an initial version in the near future. From a code perspective I have a good library in place (made a lot of changes to spectra2 in the last few years). Doing stuff in assembly language does not take as long to implement as it did before. Nonetheless, for a later version I want to have some kind of interface in place so that new functions can be implemented in a high-level language (C99?) or use a custom FORTH Next tasks are: Finally getting “save file to disk in place” Crush the remaining bugs Complete work on the command buffer (command history) Put a file picker in place. After the initial version is out: Work on a configuration file (obviously a DV80 file) and a corresponding parser Custom file settings, color schedule, etc. Implement integration with assembler and C99 compiler Seriously think about the high-level functions (search and replace, mark code, etc.) syntax highlighting (that should be fun to implement, make use of the F18a cpu in gpu?) Plugin infrastructure. Integration with TI-Basic and Force Command Custom fonts Multiple files in memory What I have implemented (but not shown and really tested yet) is a clock plugin that is shown in the status line. It runs as a background task, reads the clock file, parses & displays it. Actually it’s only a few lines of code. Quite interesting how much you can accomplish in assembly language once you have the necessary “infrastructure” in place. Really hope to have an initial version of Stevie out the door, before the F18A MK2 makes it to market.

I`ve recorded a small video in js99er with some of the features in Stevie. At this time I am very pleased with the processing speed on large files (browsing the file once it is loaded into memory). So index (re)organisation is working very well know. Even though there are still plenty of bugs. The asserts I added seem to catch most unexpected behaviour and you get the CPU crash screen. js99er-20200620215706.webm

For me there is a very important difference between TIPI and the IDE card. I love my TIPI’s, in fact I have multiple, be it as PEB card, sidecar and now also in the speech synth. What I like so much about TIPI is that they basically are software devices. What I mean by that is that allmost all of its functionality comes from software running on the raspberry. Me being a software guy, and the fact that tipi is very open (you find everything on github) allows me to try and extend things as I please. Having said that, at the same time I somehow get that “triton xt” feeling. What I mean by that is that on the other side of the line you have a device that is a LOT more powerful than the TI-99/4a itself and it somehow feels a bit like cheating. So that is the reason why I also preordered 2 IDE cards. I want to built 2 systems. One with TIPI and new devices and a more classic one with devices that were already around a long time ago. You just might call me crazy, because from a usability standpoint I’m sure TIPI is on par or beyond the IDE card. However, to me it’s not only about usability, but also letting my system be a “classic” (whatever that means, but you get the idea).

Preorders placed. 👍

This is very interesting stuff. I know this is your competetive advantage, but would you mind sharing some technical details on how the tool works and on what level. How does the work pipeline look like. I presume first step is to disassemble and work from there with the tool you implemented. Does the tool scan for certain code patterns and does code replacements or only makes hints for you then to work on. What programming language is the tool written in (python?) and what text processing libraries did you use? Again I understand if you don’t want to share these details. But heck, to me the tool and its underlying technology is as much interesting as the games that are ported with it.

There’s currently a Triple-Tech Card up for sale on Ebay and there’s a nice picture with lots of details. https://www.ebay.de/itm/Ti-99-4a-Corcomp-Triple-Tech-card-for-PEB-box/254613797358 Looking more closely I notice they sneaked a Zilog Z80 CPU on there. What is it used for? I mean the only thing the card does is: Host a speech synthesizer board Clock RS232 64k printer buffer Did I miss something? Is having a Z80 on there total overkill? Well there will be no danged Z80 in my PEB (unless perhaps me running some emulated Z80 on the raspberry in my TIPI PEB board) 😉

Yes, that’s a beauty for sure. The possibilities are endless. If only it could map the DSR space >4000 as well. With the ROS source code out there you could possibly even turn it into a HRD ramdisk. So where did you get the DALLAS SRAM’s ? Are they still available?

Upgraded from 1 assembled board to 2 assembled boards (clock with sram)

I almost missed this and am very excited about it. Having battery backed RAM opens up a lot of new possibilities. Truely hope that when the 4M SAMS released this stays an option. Would you mind sharing a picture how the card looks like?

Here’s the thread. There is a cartridge image and an updated version for loading from disk (check all posts in thread):

Trying to find and solve a bug in assembly language is a mission impossible without a proper debugger I would say. If you insist on debugging on the TI-99/4a itself, then the best debugger to use is Miller Graphics Explorer. It’s basically an TI-99/4a emulator running on the TI-99/4a itself. It allows you to single-step trough your assembly code and watch registers and memory, including VDP registers & memory as it happens. Very cool! Look for it in the development forum here, there is even an updated version of last year.

Got it ! It looked like it was plugged into the TIPI, which it’s obviously not. To my defense it’s 6.20 in the morning, so apparently eyes not fully open yet 😆

What’s that red board plugged-in to the right side of the TIPI32K?

oh wow, just got that time-warp feeling again. Thanks for pointing out the answer to a question I already asked in 2018 😃

What is the proper way to reset the F18a extended registers so that they have the same values as after a clean power-up cycle? Reason I'm asking is that if you change extended VDP registers the settings stay active even after down a "BLWP @0". In this particular case I have a crash handler in my assembly program that resets the TI to a defined state. But obviously I do not know what was set in the F18a extended registers by the calling program before. Could keep track of any value written to the F18a registers, but with the many extended registers that may get cumbersome. In my last example I turn on position-based attributes, but obviously if I reset the TI, the screen is unreadable. I know how to resolve this particular case, but would prefer a generic solution.

Thanks, I've updated the thread title accordingly.

Quick question. Does a compatible battery-backed SRAM chip exist that could replace the DSR EPROM chip? That way it could be more easy to replace the DSR contents.

That is most interesting. Would you mind posting a picture of the underside of the Strangecart? Curious to see how much space the microcontroller uses.

I've decided to rename the editor from "TiVi" to "Stevie". There are multiple reasons for doing so: In it's current form it has turned into something completely different and shares no resemblance to the well-known unix "vi" editor. It's not related to the "tipi" device in any form. So having the editor called tivi doesn't do the tipi justice in my opinion. So what's the deal with this "Stevie" name then? I still like the sound when pronouncing the name (like "TeeVee") and I very much like the music of Stevie Nicks. So there you have it. Note that I'm going to release the source code on Github in the next few weeks. Until now it was synced on Github as a private repo. But I think that the source code is now stable enough, so that I can make it available to the public.

Really like the work you are doing on Force Command and looking forward seeing where this all leads to. Especially the planned API functionality. I’d like that and want to make use of it (thinking of integrating my editor) A feature request, perhaps you can support the F18a 30 rows mode? Those 6 extra rows really do make a difference :-)

Jim, still interested in 2 completed boards. I’ll send you a PM with more details.

oh yes, I am interested in 1 populated v1 board. Payment via paypal. 😀

Here’s the link to that thread:

Was able to successfully load the TMS9900 source code on the TI-99/4a. Thanks! 😀

Tursi, thank you! I knew you’d have the numbers worked out. 😉 So that basically matches with most of what I had in mind, and it’s good to have it confirmed before starting implementation work. I’m going to experiment with different unrolls 4 and 8. But will have to come up with even larger files. I’m sure I’ll already notice a good difference with your nr80 file, but also want to try with a file of +10.000 lines.