TI99/4A questions

[Grimm1966]

 I  have been a long time reader of the content here and wanted to sign up and add my own content for whatever it's worth.    I purchased a TI99/4A many years ago (2009 or 2010 I think) and I have some questions about the serial numbers and other codes and marks on the system.  The computer works although I did have to replace the power board as one of the ICs released the magic smoke.  The serial number stamped on the case is 85875, but also there is what I think is a date code which says LTA4381.  I think it states that the computer was manufactured on the 43 week of 1981.  It's corroborated by the date codes on the motherboard chips which range from 1st week of 1980 to the 34th week of 1981.  The 43 week of 1981 would be the week of October 19th, 1981.  This would place it's manufacture about 4 months from the initial launch of the computer in June 1981. 

 

The reason I'm interested in this is because the TMS9900 CPU and the TMS9901 PSI in this computer are both ceramic and of the JDL package type.  I have had people tell me that they have a lower serial number than mine but they do not have the ceramic chips.  I was thinking the 85875 seems too low to me, so I did some basic math.  If it's correct that TI made about 3.5 million TI99/4As, and from the time it was released to when it was discontinued is around 143 weeks, then they made an average of around 24,500 computers a week.  It would take less than 4 weeks to equal the serial number on my computer, so it doesn't compute.   Even if you say they made fewer systems early on and more later it's still a stretch.  

 

My questions are, has anyone looked at the TI serial numbers and how they relate to the manufacture of the system?  Is the LTA number a date code?  I suspect that the reason this system has ceramic chips is because they ran out of the regular chips, and to keep the production going, they substituted the ceramic chips in even though they are more expensive?  

 

It would be awesome, if anyone here has a system that dates to when mine was manufactured, to open them up and see if they too have ceramic chips.  I know it's a lot to ask for as these systems are so difficult to open up, but you have my most grateful thanks if you do,

 

Jason

[Tursi]

Nice! I've not seen a ceramic 9900 in a 4A, only in 4s

 

[Archimedes5000]

For some manufacturers, you can derive the date and place of manufacture from the serial number. E.g. with the HP41. Unfortunately, that doesn't seem possible with the TI99.

Greetings Axel

[+Ksarul]

LTA=Lubbock (Test and Assembly), 43=week assembled, and 81=year of assembly, so there is a way to get the data you're looking for @Archimedes5000, just not in the serial number.

 

@Grimm1966, the manufacturing rate for the TI-99/4A was really low in 1981, as it was really just starting to ramp up after the doldrums of TI-99/4 production (from September of 1979 until June of 1981, TI only produced about 90,000 TI-99/4 machines in total--~22 months for an average run rate of about 4,000 machines a week). Production rates didn't really start to explode upward until early 1982, when TI lowered the list price to $299 (I bought mine in 1981 for $450). My original machine had a serial number close to yours--55,000 range (they used real serial numbers through much of 1981, so yours is probably correct as stamped--later they became something completely different), but I lent it to a friend in Germany when theirs died and never got it back before they returned to the US with it.

[Reciprocating Bill]

My original 99/4a, purchased (I think) in May of 1982 (and sold decades ago), had a white ceramic CPU. It was something to behold.  
 

The 9901 in the above photo also looks DeLux.

Edited January 22, 2023 by Reciprocating Bill

[Duewester]

4 boxes (3 black, 1 beige). No ceramic chips anywhere.

[Grimm1966]

11 hours ago, Ksarul said:

LTA=Lubbock (Test and Assembly), 43=week assembled, and 81=year of assembly, so there is a way to get the data you're looking for @Archimedes5000, just not in the serial number.

 

@Grimm1966, the manufacturing rate for the TI-99/4A was really low in 1981, as it was really just starting to ramp up after the doldrums of TI-99/4 production (from September of 1979 until June of 1981, TI only produced about 90,000 TI-99/4 machines in total--~22 months for an average run rate of about 4,000 machines a week). Production rates didn't really start to explode upward until early 1982, when TI lowered the list price to $299 (I bought mine in 1981 for $450). My original machine had a serial number close to yours--55,000 range (they used real serial numbers through much of 1981, so yours is probably correct as stamped--later they became something completely different), but I lent it to a friend in Germany when theirs died and never got it back before they returned to the US with it.

Thank you for confirming the date code and the production information.  Very interesting, so we should just rely on the date code and not the serial number to date these machines (and the chip date codes)?   I have another TI99/4A, a beige version and the date code (LTA4183) follows the chip dates as well, very cool.  Although the serial number for that one is 52122142 which is way too large.  

 

Jason

[Grimm1966]

5 hours ago, Duewester said:

4 boxes (3 black, 1 beige). No ceramic chips anywhere.

Are the date codes close to mine on the earlier black ones?  

[Grimm1966]

8 hours ago, Reciprocating Bill said:

My original 99/4a, purchased (I think) in May of 1982 (and sold decades ago), had a white ceramic CPU. It was something to behold.  
 

The 9901 in the above photo also looks DeLux.

Yours might have been assembled in the same batch as mine, or close to it anyway.  Very cool.

 

 Jason

[Duewester]

@Grimm1966, Sorry so long to get back to you. Been on the road.

Beige (Frankennine) = LTA 2484 (Homemade keyboard, NOT QI mainboard)

Black (Guardian) = LTA4282 

Black (Colossus) = LTA4982

Black (Sockets) = LTA1483 (Financial overload, EBay win(?) for $25 and $25 shipping. DOA - costs hundreds in new test equipment and chips but, wouldn't trade the experience.)

 

So, nothing as old as what you have

[GDMike]

I have a ceramic CPU, it's not in any of my consoles though. It's in a cabinet. Will the computer still work if I slaved it on top of an existing CPU in board.? Would it confirm it's a good cpu ii wonder.

Edited January 26, 2023 by GDMike