DATAMATH CALCULATOR MUSEUM
Texas Instruments CA-800 Cassette Interface
|Date of introduction:|| Never
(Announced: May 26, 1982
Cancelled: September 10, 1982)
|New price:||MSRP: $60.00||Display size:|
|Size:|| 6.5" x 3.2" x
165 x 82 x 33 mm3
|Weight:||7.4 ounces, 210 grams||Serial No:||1235289|
|Batteries:||1*C||Date of manufacture:||wk 56 (sic) year 1981|
|AC-Adapter:||Origin of manufacture:||USA (ATA)|
|Precision:||Integrated circuits:||TP0455/CD4511 or TP0456/CD4561, SN77203, LM393|
|Program steps:||Courtesy of:||Joerg Woerner|
The CA-800 Cassette Interface allows to use most cassette audio recorders to save programs or data files on tape. It connects to the TI-88 Programmable through a 2-pin Peripheral I/O connector. A second Peripheral I/O connector on the back of the CA-800 allows to connect another device like the PC-800 Printer to the TI-88. The CA-800 is highly reliable because its redundant recording feature whereby information is stored twice no the tape.
The Operating System of the TI-88 supports four different types of tape recordings or tape files:
|• Main memory file records all of calculator memory on tape
• Program files from a minimum of eight program steps to all of program memory
• Data files from a minimum of one data memory to all of data memory
• Numbered Constant Memory Module (CRAM) records all contents of the module on tape
Dismantling this CA-800 manufactured most likely in April 1982
(Date code indicates week 56 of year 1981) by Texas Instruments in their Abilene, TX facility,
reveals a rather complex design using a microcomputer of the
TP0456 series and a
SN77203 Voltage Controller chip together with some analog circuitry to connect
to a tape recorder. The SN77203 is known from the
TI-88 Schematics Diagram, it converts
a single-cell battery (1.2 Volts - 1.5 Volts) to two independent power supplies,
one adjustable for the LC-Display through a Serial I/O pin and one fixed for the
main electronics. Due to the lower power consumption of its electronics is the
battery life of the CA-800 projected to be 75 hour.
The TP0456 microcontroller sports Custom Design software CD4561, indicating that the original design was based on a TP0455 microcontroller with CD4511 software. Don't miss the CA-800 from an early DVT (Design Validation Test) Build featuring a translucent housing.
Color-coded plugs of the CA-800 to cassette audio recorder:
|• Black wire to remote jack
• Red wire to microphone jack
• Grey wire to earphone jack
Don't connect a CA-800 Cassette Interface or a PC-800 Printer to TI-88 calculators without the Diode-Modification!
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© Joerg Woerner, October 14, 2019. No reprints without written permission.