Airshack

I'm thinking as a beginner in Assembly the Pure-Assembly route introduces less complexity.

LWPI >8300 is indeed what I meant. I've been reading E/A which seems heavy on facts and especially light on technique. I suppose tonight's question is more of a technique question. Where does everyone put their registers, and why? Seems >8300 is commonly used since it's in the scratchpad.

So you're saying just use BLWP >8300 for your own registers and leave the >83E0 -- >83FF area alone for the Service Routines with LIMI 2. Otherwise, with LIMI 0... use BLWP >8300 and feel free to use >83E0 -- >8300 for anything else, with no worries? Sent from my iPhone using Tapatalk Pro

Just read about the Workspace Pointer being initially set to >83E0 at boot up or Reset by a Level 0 interrupt, as per the ROM Monitor . This seems well placed since the range >83E0 to >83FF is 32-bytes of the 256-byte most efficient 16-bit CPU addressable "scratchpad" RAM. Why would a non-context-switching 99/4 programmer wish move the WP elsewhere? If you routinely do so please explain to where and why? Gratitude Always. -james

Indeed! Are there any former TI employees/designers on this forum? While listening to podcasts for Apple/Atari/Tandy/Commodore/Mattel I've noticed plenty of folks being interviewed about design decisions. Many others offering up stories about the evolution of 70s and 80s machines. There seems to be a tremendous void of TI-99/4 people talking about their creation. Success or failure, that seems weird. Why? Are any AA members aware of any TI folks lurking on AtariAge or available for interview? So many unanswered questions? Ex: What was the per unit savings 1978-79 expected by going with the VDP RAM scheme over CPU static RAM?

Until...?

This past weekend the Valley of the Sun TI Users Group (VAST) gathered all active members to attend the annual Game On Expo - Phoenix. Something interesting was discovered which some of our membership may know more about: Collectorvision Games is working on a new Colecovision system with F18A built in and some form of additional expanded capabilities? The prototype motherboard can be seen in the bottom right corner of the Colecovision case above. It's hooked to a VGA/HDMI converter. Word is the final project will be HDMI. Makes one wonder when the new TI-99/4A will become a reality? Increased capabilities?

It appears the example code's fixed location actually complicated matters without providing any real gain. So it's common to use Block Starting with Symbol at the end of code to reserve memory space for variables? Trying to shift from the BASIC paradigm here. The Tombstone City code was provided with the E/A Manual I purchased. Apparently, TI felt the code was worthy of examination by those beginning with Assembly. I'm wondering if this is an exercise I should consider at this point? I've been told some of the older code from programming books of the day (80s) contain bad coding practices. Obviously some improvements in technique have materialized over the years. Any thoughts on the Tombstone City code?

^^^^^So true! Thanks guys!

http://atariage.com/forums/topic/162941-assembly-on-the-994a/?p=2414702 This PDF is an exceptional summary for anyone following this thread. Many thanks to hloberg! Reposted in case anyone missed it.

So with a full-up expanded system I don't need to concern myself with absolute code? In BASIC you can always check MEMory size as your code grows. It's probably something obvious I'm missing but how is this done in Assembly? -j

This question needs rephrasing. I know things need to be stored and 2^12 = 4K. This 4K resides in the top of the upper 24K. My question here is basically why did Matthew decide to define this range specifically?

I have a few questions about Matthew's post from way back in 19 Aug 2010. I really appreciate how he used C-ish pseudo code to describe building a data structure in Assembly. This was easy to understand as I do have some distant memories of programming in C. Again, well done and exceptionally expressed! Questions come from this line of code: BLOB EQU >F000 * 1K blob of RAM from >F000 to >FFFF A. Why do you choose to store your data structures (variables) in the "Upper" 24K? B. While messing around with mini-memory for a few days, I learned to use AORG, to set the Location Counter. This gave my object code an absolute address. Some examples (Assembly code I've examined) do not utilize the AORG Assembler Directive? Why? Seems this will put your data structures in jeopardy! C. Why wouldn't the programmer always want the object code to have an absolute address? I'm thinking to de-conflict code lines with stored data. D. If I store all my variables up in >F000->FFFF, how do I know something won't mess the numbers up later on at runtime? Much like the scratchpad gets messed with in some cases... say the way BLWP can trample on a portion of the scratchpad RAM? E. Are there any accepted best-practices for where variables are stored beyond the speedier scratchpad RAM? F. Is there a good rule of thumb regarding how to design the location of your data structures beyond the scratchpad? Seems to me I'd probably put everything there until I ran out, and then re-examine my code and later move less utilized data to the Upper/Lower RAM? I suppose my questions all concern memory management. -James

People actually USE the TI joysticks?

I'm on this thread to learn more about the 99/4. Zero skills Assembly wise thus far myself. Maybe we can work along in this together?

Those players look great! Willing to upload the Magellan file? It does seem better to start with a single-directional scrolling field, L/R or U/D. The up/down configuration you have looks great.

Thanks! Awesome tip! I'm just beginning to explore the C64. Will check it out.

Yes! I've always loved the simple 1970s Odyssey2 style football games. The maIn problem with early sports titles was no AI, so no single player mode. TI Football is a drag! It's like someone put a crappy graphical UI onto a boring turn based simulator. I remember buying it early on (1980-81) and wishing it was joystick playable, like Atari and especially Odyssey2. I'd like to remedy that situation with a simple Football game for the 99/4A. Working Title: Madden79 -James

Just thought about those old Atari ads when the topic came up. Of course, it takes a pirate to know a pirate and I know them all. It remains interesting to see how Atari ran ads against their costumers. Back in the day just about everyone in school was pirating everything. Wondering how many developers took them up on their demand to immediately contact Atari. Thankful for Omega and all the work he put into FestWest this year!

Same here! Ditto!

Pretty sure Sparkdrummer has one of those GRAM Kracker thingamabobs.

Oh my.

I'd like to join in by thanking Rich (RXB) for always reading my newbie posts and answering my many questions. The internet has provided an amazing learning opportunity for all of us. This AtariAge TI forum is 100% better than the Dallas TI User's Group I belonged to in the early 80s. We look back to those early days as amazing, which they were, yet the hobby is much more enjoyable for me now. I don't have to wait a month to ask questions and hope someone competent is in attendance. So this thank you goes out to RXB! The Easter egg in Sparkdrummer's Challenge (my compiled BASIC game) reveals a thank you to many others. -j

Now that's funny! Wondering if that Shift838 Pie image is too large to upload to AtariAge? I know all the info is out there...somewhere. It's just best to have a one-stop shopping list that's up to date. Maybe a TI fan friendly video?