kl99

The Tms9900 Cpu can address up to 64KB of memory. Certain spots in the computer are hardware wired to certain addresses of the Cpu Memory. This can not be changed, even if you would have 1 GB of memory available at one of the spots. 1. Bank #1 >0000 - >1FFF This goes to two 4K Rom chips which define the System Rom and make the first 8K of memory. In our case this is read only memory. So not usable to store anything. A bank switching project at this spot would still keep all the total memory within the Cpu Memory area of >0000 to >1FFF. You can not move to other memory locations. 2. Bank #2 >2000 - >3FFF Lower Expansion Memory. This is wired to the optional Memory Expansion that is going via Sidecar. It doesn't matter whether in a PEB or not. If you have no memory expansion, you can not write here. If you have a memory expansion, then 8K of its 32K go here. This is meant to store user data/programs. A bank switching project at this spot would still keep all the total memory within the Cpu Memory area of >2000 to >3FFF. You can not move to other memory locations. 3. Bank #3 >4000 - >5FFF This goes to the maximum of 8K of Rom chips of the active Device. The CRU chip is involved in setting active Devices and is similar like IRQ. That memory is meant to define the DSR, the Device Service Routines. In case of the Disk Controller it is the Routines to format, read, write,... In case of the RS232 it is the routines to open, close, read, write from that device... In most cases this is read only memory. In case of the RS232 HDX and the Ramdisk we have Ram chips with batteries for updates. Anyhow not meant for storing your data. As soon as another device is active its DSR is now "blended" in that >4000 - >5FFF spot. A bank switching project at this spot would still keep all the total memory within the Cpu Memory area of >4000 - >5FFF. You can not move to other memory locations. 4. Bank #4 >6000 - >7FFF This is connected to the cartridge port. Some cartridges contain a Rom chip, some a Ram chip, many don't have anything. Only when a Ram chip is connected to these address lines you can use this memory to store stuff. A bank switching project at this spot would still keep all the total memory within the Cpu Memory area of >6000 - >7FFF. You can not move to other memory locations. 5. Bank #5 >8000 - >9FFF This is the most complicated one. The TI-99/4A comes with 2x 128 bytes Ram chips, making 256 bytes total Cpu Ram. You can access it from >8300 to >83FF. There are many not connected memory areas here, meaning unless you hardware modify the mainboard, you can not make use of those. This is further the area where the memory mapping ports are: for Grom, Speech, Video Ram and Sound. A bank switching project at this spot would still keep all the total memory within the Cpu Memory area of >8000 - >9FFF. You can not move to other memory locations. 6. Bank #6 >A000 - >BFFF 7. Bank #7 >C000 - >DFFF 8. Bank #8 >E000 - >FFFF The last 3 banks (24KB) can be adressed via the Sidecar bus and therefore are meant for the 32K memory expansion, again not relevant if in a PEB or not. If you have no memory expansion, nothing can be written to here. If you have a memory expansion, this is your 2nd data/programs spot. A bank switching project at this spot would still keep all the total memory within the Cpu Memory area of >A000 - >FFFF. You can not move to other memory locations.

Hi cbmeeks, the cartridge slot is hardware wired to the Cpu memory location >6000 to >7FFF (8192 bytes). So a cartridge can either provide 8K Rom or 8K Ram to this memory location. Or nothing. Then that memory area is unused. Most third party cartridges did just provide 8K Rom (or 16K via bank switching) and that was it, the stored software is pure Tms9900 machine code. If the Rom contains a certain header, the program name will show up in the Master selection screen after the Title screen. For the TI-99 there is in addition another memory type, the Grom. It is not directly accessable by the Cpu. Therefore it is memory mapped. A certain fixed address (port) in Cpu Ram is used to see the value of the current active address of the Grom. There is another fixed address (port) to set the active Grom address. Each Grom chip contains 6K of memory, even though the Grom memory map occupies 8K for each. There are a maximum of 8 Grom chips active, the first 3 being installed in your mainboard, and up to 5 more coming via the cartridge slot. Then TI even have a mechanism for up to 16 Grom Banks. A Grom can store data or Gpl assembled code. It can store Tms9900 machine code, however the Cpu can not process a program directly from Grom, because it is memory mapped. If a Grom contains a certain header, the program name will show up in the Master selection screen. Gpl assembled code is not the same as Tms9900 machine code! Gpl assembled code still needs to be interpreted, byte by byte. The interpreter for this sits partely in the TI-99 System rom [>0024 - >08FF], which is then finally Tms9900 machine code. Any Tms9900 machine code needs to go to a Rom, any Gpl assembled code is best suited on a Grom. For general data you decide on your own. Most cartridges, released by TI were written in Gpl and were a Grom only release. When speed was critical, it was a combination of Rom (speed) and Grom (costs, size). If you were a software company and wanted to release carts for TI-99, either you bought the full license, got access to the very restricted Gpl Documentation and software and were then able to order Groms to be produced by TI. Or you wrote your software in pure Tms9900 machine code, which was fully documented and you burned your Eproms on your own. TI didn't see a penny then. At one point TI only produced mainboards with an updated System Rom [v2.2] which removed the check for Rom headers when loading the Master selection screen. This means, a cartridge with only Roms will not show up on such a TI. This essentially locked out Atari games from being loaded. Software companies started to use a cartridge schematic, where some controller made some of the Eproms appear as a Grom to the TI. This then even allowed 8K Groms instead of the usual 6K. Further to our luck, the v2.2 mainboards are not wide spread. Enjoy!

How precise is the emulation in MAME in that regards?

I think this is quite reasonable. The 99/4 was concepted at the same time the 99/3 was concepted. Further there was a 99/7 concepted. And a super secret project was building yet another 9900 based computer. Susan Bailey was in that project before it was canceled and the employees were moved to support on developing the 99/4. When comparing the specs of the 99/7 to the project she was in, she insists on theirs being a different one, and their project starting in 1977. Susan later did do the Editor/Assembler and TI-Writer for our 99/4A. What else to take into account about the 4 in our 99/4? - Originally up to 4 joysticks planned - 4 Phase clock phase - 8-bit Cpu was planned, maybe with some limitation to the number 4 - there were talks with Milton Bradley about a game machine before the 99/4, maybe naming one or more predecessor projects and 4 might have been the natural next number - it all started with 4 Gamevision Cartridges from Milton Bradley Some interesting note from the interview with Granville Ott, done by Dan Eicher in 2004: "... Len [Donohoe] wanted to develop an affordable home computer and assigned me as the architect. We presented the initial concept starting as a game and expanding to a full function computer to the corporate developmentcommittee in the fall of 1976. The committee wanted a less gamey image and we returned with the conceptfor the 99/4. ..." "Q. Who designated the name 99/4. We've always understood the 99 to come from the 9900, and the 4 from the original 4K of video RAM. There is a bit in one of the video registers to choose 4K or 16K or video RAM. Were any machines actually sold with only 4K or VDP RAM? A. We needed a series that didn’t look like a calculator name and had room for growth The 99 would tie to Austin if we could ever get them on board and to the Semiconductor product. 4 was a good starting place. The 16Ks were not affordable when we started so we designed for both 4 and 16. Semiconductor wanted us to use partials rejected from 16 production, but we refused. The 16s were available when we went to production." Also the CC-40 is using 40 in its name. Why?

Hello Curtis! Sorry to hear about your health status! I hope for you it is just a phase and will get better again. Count me interested in aquiring the Wafertape Drive. I have none of these yet. My Hex-Bus Floppy is currently only working through an external drive. So I am interested in buying one of those. It would make the setup for my CC-40, CC-40+, 99/8, 99/2 more complete. Sending you a P.M. BR Klaus

this will do for now. http://web505.104.hosttech.eu/web99/Web99%5B2015-12-25%5Dv0.5xmasedition.zip

For now, you can see the photos on the ebay auction. https://www.ebay.com/itm/Vintage-1984-Texas-Instruments-Compact-Program-Recorder-CPR-001-for-CC-40-Plus/392175399085 And you can read the manual and see some photos on http://www.ti99db.org/Hardware_view.php?SelectedID=68

My wife is doing wonders in getting me TI & retro stuff for my birthday and xmas. I am always amazed. In terms of getting a gift for yourself, I had luck finding a boxed TI Compact Program Recorder CPR-001 which originated from an TI employee. It was the smaller recorder who never appeared for sale as far as I know and was meant for the never released CC-40+. It will not be here before christmas but that doesn't matter.

Hi Opry99. Maybe you can get in contact with Jens-Eike from Germany, afaik he has Driving Demon boxed. You have his contacts?

Interesting that there is somebody from my city selling a TI-99 cartridge.

Part 1: Part 2:

Hi Ralph! Congrats on the announcement here! Is it okay to publish the video recording from your presentation at the TI-Treff 2018? I would have it prepared on youtube.com. BR Klaus

Awesome. Wahnsinn. Congrats to the Progress. I can report about some progress as well, at least I was creating some Unit Tests for TIcode99 on the weekend.

Hi wolhess, we met in Neuss. I am sure you remember talking to Klaus from Austria. Still have to deal with loss of one of my pets when I returned home. Will soon provide updated version of Web99 and will continue to work on TIcode99.

That reminds me of flying home from a TI meeting in Germany to Austria. I thought why not scan the TI-99 console in the security to see a cool xray of it. Maybe I can even take a picture of it on their monitor. So I put it in hand luggage. I ended up being asked in another room for explosive inspection of that "device". They were very suspicious about it. Oh my.

I will be there from Friday to Monday.

https://www.99er.net/cc40.html

hi, it might be enough to compare the print outs then against a printout of a default cc-40 to figure if the rom is different.

Hi Michael, this is such great achievements of you, again! Will you do a presentation about the latest Mame Updates at the TI Treff in Neuss?

Just some input from my side on the topic: Back in the late 90's the DVD Player manufactors were using the loophole of not the required Region Code Protection by shipping their players locked to one of the six regions codes. The customers then pushed some buttons off the remote control in a certain order to set their player into Regionfree mode. The same could be thought about this device here. It ships without providing any signal on the digital video port to fit all licensing requirements. User then enter a hidden debug mode which unlocks a digital video output on their device. I guess it would be sufficient if the sequence how to enter the debug mode is not shown on the offiical page. In case the license period is really running out in 2019, an updated firmware could be released to feature the digital video out of the box.

How does the logic differ from a standard eprom chip of 8K size?

Thanks for that. Didn't history show, that the TMS9901 actually combined two functions in one chip and therefore made it more expensive than required, once you added additional ports? So each Port got its own TMS9901 chip even though there was no additional CRU functionality required. At least I remember hearing some engineers complaining about that fact. Isn't the DS990-1 also not using any TMS9902, TMS9901 or TIM9904 chips on its boards?

What do you mean with PSI? I am not familiar with this word. There was a Tomy Tutor MKII released in Japan only. It featured basically the same computer, running a better keyboard (and some different ROM?). The Tomy GPL runs from Rom Chips, not Grom Chips.

If it was a late decision change and you are saying that having this correct is key for Tape loading/saving to work it could mean that the real machine is actually running in a wrong speed for it to work. I mean that the routines were not adapted yet in Rom. At least we have to consider this option.

I am blown away. You have an awesome set of not preversed documents. Only this is existing as pdf: Series 700 Intelligent Terminal Systems - 770 Field Maintenance Test - Operating Procedures http://bitsavers.org/pdf/ti/990/ds990/2262570-9701A_DS990_System_Model_1_Field_Maintenance_Test_Operating_Procedures.pdf The TPL System User's Guide is about using the Software or the Hardware as well? I wonder where I could find a note about the CPU Dip Switch meaning. Thanks for checking your state. Maybe it is about setting some CRU address?