99105/99110 Accelerators?

[Geoff Oltmans]

18 hours ago, Tursi said:

That comes up for me sometimes too. But... if it's in the same shell, and it uses the same peripherals, and it runs the same software, I'm kind of okay with it.

 

Like, I've been sorely tempted to drop a cheap PC in the console with the necessary hookups to run the hardware, and use an integrated emulator for the compatibility function. It'd be fun. If it wasn't also a multi-year full time project, I think I'd have done it already.  

 

At the end of the day it’s all for funsies, isn’t it?

[+FarmerPotato]

Thinking about which chips are more likely for a socket-compatible plug-in board:

 

Since the 9900 socket has a 16-bit bus, the 9995 needs lots of redundant chips. 
The 99105 has a 16-bit bus and might be "less difficult". 
 

Then I considered  the TMS38010 again. I am calling this chip "The Last 9900." It was released  late in 1985! It was built to process token ring frames at 3 MBps.

 

(The TMS380 was conceived under TI's new Microprocessor Group strategy under Wally Rhines, which also produced the home run TMS320, and TMS340.) 
 

The databook omits the CRU instructions, which would have to be emulated if they don't exist. It has the 9995 instructions MPYS, DIVS, LWP, etc. It has 2.5K of parity RAM onboard, but some device register holes in 0000-0FFE. So original ROMs would be problematic.  
 

Its advantage is blazing fast execution in that RAM region!!!

 

In addition to 16K of external ROM firmware, TI supplied a tiny binary to run out of that onboard RAM.

 

The code in onboard RAM was the LLC (Logical link control). This term refers to the OSI networking model. LLC is just above the physical layer and "defines the way data is formatted for transmission and how access to the network is controlled." I quote this to indicate that it must have very fast throughout. 

 

 

The TMS38010 has a 333 ns cycle time like the 9900,  but seems  to have the pipeline optimizations of the 9995 and 99105.

 

If the TMS38010 is a bad fit for a 9900 replacement, WHAT IF it could be reprogrammed to be an Ethernet coprocessor?

 

At least one person did this at TI in the 1990s.

 

 

[+FarmerPotato]

Or the TMS38010 as a floating point coprocessor?

This idea follows my philosophy of "Use original chips."

 

 

As a dedicated floating point coprocessor next to the 9900, it could trap the 4A ROM floating point entry addresses, putting the 9900 into wait states.
 

Then it would run code from its onboard RAM, finally placing the result in FAC.
 

To return control to the 9900, it places a return opcode (or branch) onto the data bus and releases READY. The 9900 reads the opcode and returns to the caller, unaware of the coprocessor. 

 

With the TMS38010 internal optimizations, I bet it could execute floating point code several times  faster than the 9900. Since registers and PAD are in memory, the 9900 hides no internal state. The coprocessor reads FAC and ARG from PAD on the 4A bus.  
 

Other ROM routines might also be patched in this way.

 

To return control to the 9900, the coprocessor puts the appropriate branch or return opcodes on the bus, so the 9900 jumps over the original ROM  code. 
 

I'm intrigued by what you could do with actual chips from the period--not FPGA upgrades. 

[Colin]

I've managed to get my ASR733 system working and extracted quite a few 99/4a files that may be of interest - in particular the DSR descriptions mentioned above some time back.

https://www.blunham.com/Misc/Texas/Mine/index.html

Colin Hinson.

[Gary from OPA]

38 minutes ago, Colin said:

I've managed to get my ASR733 system working and extracted quite a few 99/4a files that may be of interest - in particular the DSR descriptions mentioned above some time back.

https://www.blunham.com/Misc/Texas/Mine/index.html

Colin Hinson.

Thank you Colin, as usual your vast archive of TI history and making it available to us is greatly appreciated.

[+Ksarul]

9 hours ago, Colin said:

I've managed to get my ASR733 system working and extracted quite a few 99/4a files that may be of interest - in particular the DSR descriptions mentioned above some time back.

https://www.blunham.com/Misc/Texas/Mine/index.html

Colin Hinson.

I noticed what look to be disassemblies of all three Thorn EMI cartridges in there. I saw a note in the Computer War (high) file that you had relocated it--I take it that this change moved it out of 32K (sideport) and DSR ROM space and into cartridge ROM space. If so, that explains a lot about how MicroPAL was able to release that title as a standard cartridge (but kept the other two running out of expansion memory).

[Colin]

I had (have) all three of the Thorn softwares running in cartridges - these came to me on floppy and I dis-assembled them and arranged them to run in cartridges.  I also did the same with a heap of others such as TI runner (48k !).  These were never released by me - purely for our kids and my wife and I.  I also have a heap of disks, some of which I have the .hfe file for but can't get HXC to generate a 99/4a file for them (it crashes).  Any ideas? (I don't currently have a working 99/4a system).

An example of this is here (it's my Tennis Cartridge)

https://https://www.blunham.com/Misc/Texas/Mine/TennisCartridge.hfe

Colin.

[Gary from OPA]

32 minutes ago, Colin said:

I had (have) all three of the Thorn softwares running in cartridges - these came to me on floppy and I dis-assembled them and arranged them to run in cartridges.  I also did the same with a heap of others such as TI runner (48k !).  These were never released by me - purely for our kids and my wife and I.  I also have a heap of disks, some of which I have the .hfe file for but can't get HXC to generate a 99/4a file for them (it crashes).  Any ideas? (I don't currently have a working 99/4a system).

An example of this is here (it's my Tennis Cartridge)

https://https://www.blunham.com/Misc/Texas/Mine/TennisCartridge.hfe

Colin.

Try the TI Image Tool v3 from. @mizapf that should able to open your HFE file and then you can copy the contents to a normal like 360k DSK image, etc.

 

 

[+dhe]

@Gary from OPA  was the only person I ever saw with a WORKING accelerator.  Maybe he would like to mention his experience.

[Gary from OPA]

20 minutes ago, dhe said:

@Gary from OPA  was the only person I ever saw with a WORKING accelerator.  Maybe he would like to mention his experience.

Been thinking of building one again just for fun. But it's easier to either a) use the smj68689 instead no need for extra demux logic and that processor is more than ten times faster than the 9900, OPA used the smj68689 in our GMTA kiosk devices. Or b) use the fpga ti99 which uses a tms99105 that project would be nice to expand on and add more features, another item on my Todo list.

 

As for the actual 99105 on a stock ti99 console, the timing is a bitch in hell as first you got to demux the pins from 99105 then the /4a messes it all up by converting it back to 8bit bus with wait states, double mess.

 

Doing a new one today, it would be best to include a full 16bit bus with everything on it like f18a, Sams, horizon, grom, ram and remove the wait state 8 bit support for the peb totally and use a pico w to emulate speech, p-code Scsi, floppy support.

Edited Monday at 12:58 AM by Gary from OPA