Anybody with experience with the TMS9911 DMA controller?

[pnr]

I'm aware of only one (publicly available) design that incorporates the TMS9911 DMA controller, and that is the Powertran Cortex.

 

In particular I was wondering about its clock input. In the Cortex design this is hooked up to the *inverted* CLKOUT signal of the 9995 CPU. From studying the data sheet, I see no particular reason for this inversion. The datasheet does refer to this input as inverted ø, but that is probably because it refers to the inverted ø1 output of the TIM9904 or the inverted ø3 output of the TMS9980/9981 as possible sources for this signal.

 

Does anybody know of other (public) designs using that chip, or have experience with it?

 

[Stuart]

(Major digression - here's a chap who apparently helped to design the 9911 - https://www.linkedin.com/in/longley/. He also claims to have done the product definition for the TMS9909 floppy disk controller, and that that chip was in full production for 8 years. For a chip that was produced for so long, it is mighty hard to get hold of one, and I don't think anyone has seen one that isn't the 'TMX' prototype version.)

[jbdigriz]

Unfortunately behind LinkedIn's joinwall, which was actually a highly annoying stealth paywall the one time I joined some years ago. I canceled the subscription they snookered me into and never looked back. Now of course I miss out on a lot of useful info. Nothing I can do about that except urge all you corporate soldiers out there to post any stories you can share, like the one above, in a more accessible place, such as a blog post, or, indeed, this very forum. They will be greatly appreciated.

 

I don't have a 99/4P CPU handy to look at, but didn't Becker use a 9911 for DMA on that?

Edited September 21 by jbdigriz

[jbdigriz]

Found a pic on the SNUG site; yes, he did. 

 

 

[+dhe]

Almost like Mr. Becker knew what he was doing!

[speccery]

13 hours ago, jbdigriz said:

Found a pic on the SNUG site; yes, he did. 

 

 

I took a quick look at hires version of this picture and I don’t see a 9911 there, there is just the common TMS9901 I/O chip. Am I missing something?

I’d be interested in learning more about the 99/4P though. I’ve stumbled on mentions about it before but don’t know much about it.

[jbdigriz]

Yeah, that's kind of a potato pic above. Glad you found one better. So, I misread. No 9911. I do recall mention of the 4P having DMA, so maybe it's in that [edit] Mach 2 CPLD ( according to SNUG doc, plus I found a better pic myself.) along with everything else they're doing there.

Edited September 22 by jbdigriz

[RickyDean]

9 hours ago, speccery said:

I took a quick look at hires version of this picture and I don’t see a 9911 there, there is just the common TMS9901 I/O chip. Am I missing something?

I’d be interested in learning more about the 99/4P though. I’ve stumbled on mentions about it before but don’t know much about it.

Could you share that HR pic, or give a pointer to it's location, I'd like to see what's there too. Thanks in advance.

[jbdigriz]

There are good pics of many 3rd-party boards, including the SGCPU, here.

[RickyDean]

1 minute ago, jbdigriz said:

There are good pics of many 3rd-party boards, including the SGCPU, here.

Okay, thanks, I was looking there yesterday, but for some reason this eluded me. Yes, it's a much better picture.

[jbdigriz]

10 hours ago, speccery said:

I’d be interested in learning more about the 99/4P though. I’ve stumbled on mentions about it before but don’t know much about it.

The SNUG system is awesome. Never was able to afford one, and sadly no longer in production afaik. There was also a 99/5P mentioned. Don't recall any details or if it was actually produced. Thankfully there is the MAME/MESS emulation of the /4P.

Edited September 22 by jbdigriz

[+dhe]

I have a SNUG system, minus the speech card. Herr Becker's goal was to build the best cards possible.

Ones that could literally last a life time. Example: Gold Connectors, Machine Pin Sockets, all IC Socketed, etc.

 

Also, if you look at all the cards design, they all have an FPGA, that pulls the bus and what it is doing together.

 

Almost any problems that could arise in a design could be fixed by reprogramming the FPGA to handle it.

 

Yea.. I'm a huge fan. 😃 

[Gary from OPA]

10 minutes ago, dhe said:

I have a SNUG system, minus the speech card. Herr Becker's goal was to build the best cards possible.

Ones that could literally last a life time. Example: Gold Connectors, Machine Pin Sockets, all IC Socketed, etc.

 

Also, if you look at all the cards design, they all have an FPGA, that pulls the bus and what it is doing together.

 

Almost any problems that could arise in a design could be fixed by reprogramming the FPGA to handle it.

 

Yea.. I'm a huge fan. 😃 

yes, the set of cards he made are great. -- Just too bad they are so super rare, and next to impossible to get today, and sadly none of the designs were released either.