11-29-2015, 08:59 PM
I got this tiny little pocket calculator since some time ago.
The seller told me it was working but when I collected it in my mailbox it was not.
Basically it doesn't power on.
Today I took some time to have a look.
This is one of many implementations from different vendors that used the Texas Instruments TMS0105 "Calculator on a Chip" in the 70's.
My specimen uses a TMS0105BNC variant and has a date code of 7303 (1973, week 03).
![[Image: busicom_le-80a_002.jpg]](http://3.bp.blogspot.com/-3ZSDfMn1lew/VltJvcTlI9I/AAAAAAAADsI/PUq4shIkbqs/s1600/busicom_le-80a_002.jpg)
As usual, someone forgot the LR1 batteries inside and it leaked corroding the copper traces in the battery holder section.
So I have just used an 4 x 1.5V AA external battery holder to test it.
It worked at first try.
![[Image: busicom_le-80a_004.jpg]](http://4.bp.blogspot.com/-KuNJLiHhMaA/VltJw2MTDiI/AAAAAAAADsY/u5WE58MNV5k/s1600/busicom_le-80a_004.jpg)
It uses a Browmar Optostic 9-digit 7-segment LED display.
The display is amazing. Look to those tiny dots (LED's) on each segment!
![[Image: busicom_le-80a_005.jpg]](http://1.bp.blogspot.com/-IjYyunCzYZQ/VltJ4f0kkOI/AAAAAAAADsk/WIKO-jHYjDo/s1600/busicom_le-80a_005.jpg)
The calculator do not have a dedicated "=" key.
Trying: 12345679 x 9 += I get this result with a "u" indicator (overflow positive?):
By the way, does anyone have information on the indicators used by these TMS0105 processors?
![[Image: busicom_le-80a_006.jpg]](http://2.bp.blogspot.com/-Wa8oJSFGIJ4/VltJ7aJ6o5I/AAAAAAAADsw/CAWAy8XTmtM/s1600/busicom_le-80a_006.jpg)
Trying: 12345679 x 9 -= I get now two indicators, "-" and "u" (overflow negative?):
![[Image: busicom_le-80a_007.jpg]](http://3.bp.blogspot.com/-4q_PvszwNLg/VltKPLDStZI/AAAAAAAADtA/CjNMdOositc/s1600/busicom_le-80a_007.jpg)
Entering all eights and I get this "C" indicator:
![[Image: busicom_le-80a_008.jpg]](http://4.bp.blogspot.com/-1mRAsSlrPqs/VltJ7u0FSrI/AAAAAAAADs0/ywzG9I8gwy0/s1600/busicom_le-80a_008.jpg)
And entering a negative number:
![[Image: busicom_le-80a_009.jpg]](http://3.bp.blogspot.com/-MTWCpXFvY7s/VltM33ec55I/AAAAAAAADtM/Y-Jzm0fFodw/s1600/busicom_le-80a_009.jpg)
(to be continued)
The seller told me it was working but when I collected it in my mailbox it was not.
Basically it doesn't power on.
Today I took some time to have a look.
This is one of many implementations from different vendors that used the Texas Instruments TMS0105 "Calculator on a Chip" in the 70's.
My specimen uses a TMS0105BNC variant and has a date code of 7303 (1973, week 03).
![[Image: busicom_le-80a_001.jpg]](http://2.bp.blogspot.com/-ibkUTMRHfLE/VltJuD49ftI/AAAAAAAADsE/fkxn36x9Ya0/s1600/busicom_le-80a_001.jpg)
![[Image: busicom_le-80a_002.jpg]](http://3.bp.blogspot.com/-3ZSDfMn1lew/VltJvcTlI9I/AAAAAAAADsI/PUq4shIkbqs/s1600/busicom_le-80a_002.jpg)
As usual, someone forgot the LR1 batteries inside and it leaked corroding the copper traces in the battery holder section.
So I have just used an 4 x 1.5V AA external battery holder to test it.
It worked at first try.
![[Image: busicom_le-80a_003.jpg]](http://3.bp.blogspot.com/-ZzezssqdoN4/VltJvwjm40I/AAAAAAAADsM/fKHaTvbJqTw/s1600/busicom_le-80a_003.jpg)
![[Image: busicom_le-80a_004.jpg]](http://4.bp.blogspot.com/-KuNJLiHhMaA/VltJw2MTDiI/AAAAAAAADsY/u5WE58MNV5k/s1600/busicom_le-80a_004.jpg)
It uses a Browmar Optostic 9-digit 7-segment LED display.
The display is amazing. Look to those tiny dots (LED's) on each segment!
![[Image: busicom_le-80a_005.jpg]](http://1.bp.blogspot.com/-IjYyunCzYZQ/VltJ4f0kkOI/AAAAAAAADsk/WIKO-jHYjDo/s1600/busicom_le-80a_005.jpg)
The calculator do not have a dedicated "=" key.
Trying: 12345679 x 9 += I get this result with a "u" indicator (overflow positive?):
By the way, does anyone have information on the indicators used by these TMS0105 processors?
![[Image: busicom_le-80a_006.jpg]](http://2.bp.blogspot.com/-Wa8oJSFGIJ4/VltJ7aJ6o5I/AAAAAAAADsw/CAWAy8XTmtM/s1600/busicom_le-80a_006.jpg)
Trying: 12345679 x 9 -= I get now two indicators, "-" and "u" (overflow negative?):
![[Image: busicom_le-80a_007.jpg]](http://3.bp.blogspot.com/-4q_PvszwNLg/VltKPLDStZI/AAAAAAAADtA/CjNMdOositc/s1600/busicom_le-80a_007.jpg)
Entering all eights and I get this "C" indicator:
![[Image: busicom_le-80a_008.jpg]](http://4.bp.blogspot.com/-1mRAsSlrPqs/VltJ7u0FSrI/AAAAAAAADs0/ywzG9I8gwy0/s1600/busicom_le-80a_008.jpg)
And entering a negative number:
![[Image: busicom_le-80a_009.jpg]](http://3.bp.blogspot.com/-MTWCpXFvY7s/VltM33ec55I/AAAAAAAADtM/Y-Jzm0fFodw/s1600/busicom_le-80a_009.jpg)
(to be continued)