ÍAIL ÆROM: ÒECURSION ÄATE: ÓUNDAY 4-ÆEB-90 16:30 ÅÓÔ ÈOW TO ADD A SECOND SID TO A Ã64 AT $D700 INSTEAD OF $DE00 OR $DF00. ÙOU NEED A 74ÌÓ139 OR 74Æ139. ÔHIS IS A DUAL 2 TO 4 LINE DECODER /DEMULTIPLEXOR. É RECCOMMEND YOU USE THE FAST 'Æ' VERSION. ÎOTE THAT PIN NUMBERING ON ÁÌÌ CHIPS IS COUNTER-CLOCKWISE FROM THE TOP LEFT PIN. ÔHE REFERENCE MARK SHOWS THE TOP OF THE CHIP. ***ÒEFERENCE MARK (DOT OR NOTCH)*** ÐIN PIN 1 *SEE NOTE* 16 +5 VOLTS 2 Á8 15 NO CONNECTION 3 Á9 14 NO CONNECTION 4 ÓÉÄ #1 PIN 8 13 NO CONNECTION 5 *1* 12 NO CONNECTION 6 *2* 11 NO CONNECTION 7 ÓÉÄ #2 PIN 8 10 NO CONNECTION 8 ÇROUND 9 NO CONNECTION Á8 AND Á9 CAN BE FOUND AT EITHER THE EXPANSION PORT, OR THE 6510 ÃÐÕ CHIP. ÌOOK IN THE APPENDIX OF EITHER THE ÐROGRAMMERS REFERENCE GUIDE, OR THE USERS GUIDE THAT COMES WITH A C64. ÁNYWHERE ELSE YOU MANAGE TO FIND THESE SIGNALS IS OKAY TOO. ÔHE SAME GOES FOR +5 VOLTS AND ÇROUND. *************ÃONTINUED************* -::- ÍAIL ÆROM: ÒECURSION ÄATE: ÓUNDAY 4-ÆEB-90 16:35 ÅÓÔ ÈOW TO ADD A SECOND SID TO A Ã64 AT $D700 INSTEAD OF $DE00 OR $DF00. ÙOU NEED A 74ÌÓ139 OR 74Æ139. **************ÐART 2**************** *ÎOTE* ÆIND THE 6581 ÓÉÄ CHIP ALREADY IN THE Ã64. ÔAKE IT OUT OF ITS SOCKET, AND BEND PIN 8 UP UNTIL IT IS HORIZONTAL. ÃONNECT PIN 4 OF '139 TO THIS PIN. ÓOLDER A WIRE CAREFULLY INTO THE SOCKET HOLE FOR PIN 8 OF THE ÓÉÄ, AND CONNECT IT TO PIN 1 OF THE '139. ÈOOK UP THE SECOND SID AS IN SEVERAL ARTICLES, ÂÕÔ CONNECT PIN 8 OF THE ÓÉÄ#2 TO PIN 7 OF THE '139. ------------------END----------------