Talk:TMS9900

message: There's a neutrality disputed tag on the main page, but no discussion of neutrality in the talk page - what's up? At first reading, the article feels like it's been written by an enthusiast of the chip, but it doesn't seem wildly at variance with NPOV. Rob Burbidge (talk) 12:16, 16 September 2009 (UTC)
replies: text: I believe the issue lies with the fact that there aren't any references cited whatsoever. Which is why you would put a citations needed notice...Most or all of what is said is true, but without citing sources or going into detail, one could dispute the neutrality. For instance, the claim about how it "had the potential to surpass the 8086." It does strike me as rather bad taste to add that "neutrality disputed" notice without any talk. Since there's no talk, I think it should be replaced with a "lacks citation" notices, unless anyone wants to raise any real objections... Sidenote, the citation needed/lacks verification notices are getting far too annoying all over Wikipedia; it seems every other article I look at (I mostly browse technical articles) has them. Sigh. Citations are often just a google away.. pokeme444 (talk) 6:52, 4 May 2010 (UTC)
thread_title:  Neutrality 

message: the page is full of speculation and inaccurate information.  coming from someone who owned nearly every micro-processor available in 1978 - 1988 and memorized their instruction sets.
just some examples:
# the processor is big endian in that the low order address bit, A15 (which did no appear on the address pins of the chip) addressed the rightmost byte of a 16 bit word if 0, and addressed the leftmost byte of a 16 bit word if 1. (and yes, it is confusing at first that TI choose the pin numbers not as 2^N, but as A0=high and A15=low.  Same for D0-D15.
# the instruction set is nearly a complete ripoff of the PDP 11, but with 4 bits of register addressing.
# the AMD 2901 bit-slice and the National Bit-slice chips are not "microprocessors", they are bit-slice, which meant that any processor built with them was multi-chip by nature (ALU, Instruction decode, address/data buss management were separate chips)
# the IBM-PC team in Boca Raton seriously consider the TMS9900 for the original PC, but decided on the 8088 based on a variety of reasons including production costs.
# the TMS9900 was one of very few microprocessors which was available in a radiation hardened version, and it became popular in military hardware for guidance and control systems for missiles and aircraft.
# I have serious reservations about the statement someone made that "every illegal opcode executes as a NOP" ... that does not agree with my personal experience with the processors used in the TI-99 and the later MyARC Geneve (TMS 9995).  There were undocumented instructions in various production runs, and they had various side-effects.  One which comes to mind is a buggy and incomplete implemention of MPY (multiply) which was on a 1985 production TMS 9900.
# I don't understand someone's reference to "distributed computing" in the context of the X (eXecute) instruction.  It was useful for debugging and for creating an indexed-opcode table used in a byte-code interpreter.  Typical form was "X @BASE+INDEX".  The drawback I recall is that the 2nd word (if needed) when the instruction was decoded was pulled from after the X instruction, not from after the target of the X instruction.  My recollection may be faulty -- I need to reread the instruction datasheet.
# discussion below, regarding RSET, LREX, etc.  yes, they drove the 3 HIGH order address PINS in a non-memory address cycle along with CRUCLK.  If there was no external hardware to detect the non-memory address cycle, then nothing special happened, and the instructions only vectored as documented.
I may take a try at cleanup with cites.
Techguru99 (talk) 13:41, 18 June 2010 (UTC)
thread_title:  Inaccuracies 

message: what is the neutrality issue?
whoever initiated the claim should at least discuss it, or remove it. it is distracting .
also, the list of 'inaccuracies' is really a list of statements, mostly not even addressing any inaccuracies in the article. i don't understand point 2, the 'ripoff' statement.
the opcodes are NOT the same as the PDP11. eg;  mov is 001 for the PDP, but 110 in the TMS.
similarly, 010/100 for com, 011/110 for subtract, etc.
the article IS very sparse for a chip this powerful and popular, though
96.8.145.192 (talk) 09:35, 23 April 2011 (UTC)
thread_title:  what is the problem? 

message: It would be nice to add an example subroutine, such as the strtolower() example used for some of the other microprocessors (e.g., 6502, 80386, 68000, etc.). — Loadmaster (talk) 17:38, 22 May 2018 (UTC)
thread_title:  Example code