/-----------------\ | TI-85 LINK info | | Port 7 | \-----------------/ by Branislav Bozgai bozgai@svf.stuba.sk 1995 Connector: ---------- _____ Jack 2.5mm stereo | | - GND (Ground) |_| |_| - W (White wire) |_| - R (Red wire) Electrical performance: ----------------------- All data are transmitted in binary form - logical '1' or '0' 1 = 5V (4.9V) 0 = 0V but TI-85 uses 'negative logic' that means: 0 (0V) = active signal 1 (5V) = not active So when you turn your calculator ON you can measure between W and GND 5V (also between R and GND 5V) that means everything is in quiet state. Programming: ------------ Sending: If you want to make some wire active: OUT(7),\$E8 ; W=0, R=1 OUT(7),\$D4 ; W=1, R=0 OUT(7),\$FC ; W=0, R=0 To deactivate signals: OUT(7),\$C0 ; W=1, R=1 In assembly (e.g. if I want to make W active): LD A,\$E8 OUT (7),A You can use other numbers to out (but may cause abnormal operation, I think that I can explain how it works) but TI's system is using only those above. Note: Don't forget to out \$C0 at the end of transmittion otherwise both sending and receiving calculators slow down. TI is using \$FC to signalise an error. Reading: IN A,(7) AND 3 ; upper bits are not important CP 3 JR Z, Nothig_is_active ; W=1, R=1 CP 2 JR Z, R_is_active ; W=1, R=0 CP 1 JR Z, W_is_active ; W=0, R=1 CP 0 JR Z, W_and_R_are_active ; W=0, R=0 \$C0 = 192 = %11000000 \$D4 = 212 = %11010100 \$E8 = 232 = %11101000 \$FC = 252 = %11111100 All routines related to link port are in ROM page 5. In TALK I'm using ROM_send_byte and ROM_read_byte routines. ROM_send_byte is at address: \$643B = LD C,A to \$647C = RET Input: A - byte to send Destroys: DE, BC, HL ROM_read_byte is at address: \$6559 = LD B,\$08 to \$65CB = JR \$6603 Output: A - received byte Destroys: DE, BC, HL But I'm mot calling this routines directly because they both call function \$0A87 (which is error handler I think) which cause crash. Can somebody help with that? I've modified them slightly replaced JP to JR and JP \$0A87 to RET. ********************************************************************* There were questions on calc-ti about where can people get from Dan Eble's ZShell and other asm progs. So I'm running anonymous FTP server at address: ftp.svf.stuba.sk There is directory ti and there you'll find everything you want. Feel free to upload anything you want into ti/incoming. I'll move it into readable area within a week. NOTE:If you can't get connection, the server may be down so please try later (we are trying to keep it in work non-stop but we have some problems) Any comments or questions to this file mail to: bozgai@svf.stuba.sk or copy to /dev/null :)