+- 99er Forums (http://www.99er.net/99erbbs)
+-- Forum: TI-99/4A & Related Computers (http://www.99er.net/99erbbs/forumdisplay.php?fid=4)
+--- Forum: Questions, Projects, etc. (http://www.99er.net/99erbbs/forumdisplay.php?fid=9)
+--- Thread: decoding address lines on TI 994a (/showthread.php?tid=5)
decoding address lines on TI 994a - sjt99 - 04-18-2014
Hi
Wondering if anyone reading this can walk me through handling decoding address lines on the TI.
Looking to possibly add a A/D convertor for example.
I assume I would have to use something like a 74ls138 decoder but not sure how to use the truth table to address the ti memory, say at the end of expansion memory.
Exactly how can I place data at a specific address block?
If someone out there has any examples of how this was done? write ups etc
Please share them.
Years ago there was a clock/ A/D card that did this for example.
( couldn't find a schematic)
I don't know if anyone did a write up on this, in detail .
Steve
RE: decoding address lines on TI 994a - Ed in SoDak - 04-18-2014
The X-10 system ran on the TI as I recall. It sent commands to modules that could control AC lights and appliances, all monitored and operated from a TI and other supported systems. Last I saw, there was still some people using this neat software/hardware application. That probably had some form of A/D conversion at its root.
There was also a PE Box card designed for prototyping. I'm woefully ignorant what it all entails. Maybe a cruise of the Micropendium archives would reveal some stuff. They reported on all sorts of TI modifications over the years. There used to be TI newsletter pretty much dedicated to hardware hacking. Probably archived on the whtftp site.
Plenty out there on TI internals in the reference books and manuals, get ready for some deep reading.
I was curious about it back then, but my own TI systems would often lock up during long unattended sessions, making it difficult to trust them to a 24/7 type of control of a "whole-house" system like the X-10.
A lot can be done if you know TTL, driver design and how to energize relays from a data or control line or via software. Any of these suggestions might help you with how to access specific data location to feed to an external circuit. Might be a long search, but I don't have anything specific to point you directly to what you seek.
-Ed
RE: decoding address lines on TI 994a - sjt99 - 04-18-2014
(04-18-2014, 06:43 PM)Ed in SoDak Wrote: The X-10 system ran on the TI as I recall. It sent commands to modules that could control AC lights and appliances, all monitored and operated from a TI and other supported systems. Last I saw, there was still some people using this neat software/hardware application. That probably had some form of A/D conversion at its root.
There was also a PE Box card designed for prototyping. I'm woefully ignorant what it all entails. Maybe a cruise of the Micropendium archives would reveal some stuff. They reported on all sorts of TI modifications over the years. There used to be TI newsletter pretty much dedicated to hardware hacking. Probably archived on the whtftp site.
Plenty out there on TI internals in the reference books and manuals, get ready for some deep reading.
I was curious about it back then, but my own TI systems would often lock up during long unattended sessions, making it difficult to trust them to a 24/7 type of control of a "whole-house" system like the X-10.
A lot can be done if you know TTL, driver design and how to energize relays from a data or control line or via software. Any of these suggestions might help you with how to access specific data location to feed to an external circuit. Might be a long search, but I don't have anything specific to point you directly to what you seek.
-Ed
Thanks for the reply
I had heard there was an x10 interface of some sort.
I never saw it though...I am curious about that one as well.
I had built a dsr card...way back that eventually had a clock that loaded data in memory. I think that maybe the current menu program can access that area and display the clock info if there...
Someone will have to verify this.
RE: decoding address lines on TI 994a - Ed in SoDak - 04-18-2014
Glad you got something useful out of that rambling, lol. X-10 is still around, you don't hear much about the TI implementation though, but maybe some searching will lead you to the circuits if not the original TI X-10 module/software. Cool beans for the time and the concept has survived the years. http://www.x10.com/home/
Micropendium did do a fairly complete job of at least mentioning then-current hardware projects that people were playing with. I'm re-reading the June-August '89 3-parter about building a portable TI with several bells and whistles in the console.
-Ed
RE: decoding address lines on TI 994a - ksarul - 04-19-2014
The X-10 was a module that connected into the TI along with a cable that attached between the TI Joystick port and the X-10 household controller that controlled individual X-10 devices. The module software allows you to program the controller--and it then carries out the instructions. The computer is only necessary to make program changes. I have one. . .
The MBP (or MBP-II) PEB cards were probably the A/D cards you were thinking of. I think the last run of those was done by Cecure Electronics in the mid-1990s.
It is also possible to build a A/D board using the TI or Willforth prototype boards (or likely with the one I designed but I haven't done a run of these yet).
RE: decoding address lines on TI 994a - sjt99 - 04-19-2014
(04-19-2014, 02:55 PM)ksarul Wrote: The X-10 was a module that connected into the TI along with a cable that attached between the TI Joystick port and the X-10 household controller that controlled individual X-10 devices. The module software allows you to program the controller--and it then carries out the instructions. The computer is only necessary to make program changes. I have one. . .
The MBP (or MBP-II) PEB cards were probably the A/D cards you were thinking of. I think the last run of those was done by Cecure Electronics in the mid-1990s.
It is also possible to build a A/D board using the TI or Willforth prototype boards (or likely with the one I designed but I haven't done a run of these yet).
If you have designed a card for this please walk me thorough how you activate the A/D or clock to output data to certain memory addresses?
I want to understand how you decode the address lines to enable the output for certain memory addresses.
Steve