BBC FRED Hardware I/O Addresses =============================== Addr Write Action Read Action ------------------------------------------------------------------------- FC00-03 Byte-Wide Expansion RAM =============================== FC00 RAM Card Address b0-b7 RAM Card Address b0-b7 FC01 RAM Card Address b8-b15 RAM Card Address b8-b15 FC02 RAM Card Address b16-b23 RAM Card Address b16-b23 FC03 RAM Card Data RAM Card Data FC04 FC05 FC06 FC07 FC00-FC01 PEDL Z80 Second Processor =================================== FC00 Status Command FC01 Data port to CoPro Data from CoPro FC08-0F Ample M2000/EMR/EE MIDI Interface (see also FCF0) ========================================================= FC08 MIDI Port 1 6850 Control MIDI Port 1 6850 Status FC09 MIDI Port 1 6850 Data MIDI Port 1 6850 Data FC0A MIDI Port 2 6850 Control MIDI Port 2 6850 Status FC0B MIDI Port 2 6850 Data MIDI Port 2 6850 Data FC0C MIDI Port 3 6850 Control MIDI Port 3 6850 Status FC0D MIDI Port 3 6850 Data MIDI Port 3 6850 Data FC0E Output latch - FC0F Output latch - FC10-13 Teletext Hardware ========================= FC10 ? ? FC11 ? ? FC12 ? ? FC13 ? ? FC14-1F Prestel Hardware ======================== FC14 FC15 FC16 FC17 FC18 FC19 FC1A FC1B FC1C FC1D FC1E FC1F FC20-3F SID Interface (6581 Sound Interface Device) =================================================== Voice 1: FC20 Frequency Low - FC21 Frequency High - FC22 PW Low - FC23 PW High - FC24 Control register - FC25 Attack/Decay - FC26 Sustain/Release - Voice 2: FC27 Frequency Low - FC28 Frequency High - FC29 PW Low - FC2A PW High - FC2B Control register - FC2C Attack/Decay - FC2D Sustain/Release - Voice 3: FC2E Frequency Low - FC2F Frequency High - FC30 PW Low - FC31 PW High - FC32 Control register - FC33 Attack/Decay - FC34 Sustain/Release - Filter: FC35 FC Low - FC36 FC High - FC37 Reset/Filter - FC38 Mode/Volume - Misc: FC39 - POTX FC3A - POTY FC3B - OSC3/Random FC3C - ENV3 FC3D - - FC3E - - FC3F - - FC20-27 IEEE Interface (TMS 9914A) ================================== FC20 Interupt Mask 0 Interupt Status 0 FC21 Interupt Mask 1 Interupt Status 1 FC22 - Address Status FC23 Auxilary Control Bus Status FC24 Address - FC25 Serial Poll - FC26 Parallel Poll Command Pass Through FC27 Data Out Data In FC28-2F Electron Econet ======================= FC28 FC29 FC2A FC2B FC2C FC2D FC2E FC2F FC30-3F Cambridge Ring interface ================================ FC30 FC31 FC32 FC33 FC34 FC35 FC36 FC37 FC38 FC39 FC3A FC3B FC3C FC3D FC3E FC3F FC40-4F Hard Drive Access ========================= SCSI Interface IDE Interface Addr Write Action Read Action Write Action Read Action ------------------------------------------------------------------------- FC40 Data Out Data In Data Low Data Low FC41 - Status Special Error FC42 Select - Count Count FC43 INT enable - Sector Sector FC44 Cylinder Low Cylinder Low FC45 Cylinder High Cylinder High FC46 Head+Drive Head+Drive FC47 Command Status FC48 Data High Data High FC49 - - FC4A - - FC4B - - FC4C - - FC4D - - FC4E Digital Output Alternative Status FC4F - Drive Data FC50-51 BeebEm clipboard access =============================== FC50 &00 if clipboard character waiting FC51 Clipboard character FC52 FC53 FC54 FC55 FC56 FC57 FC58 FC59 FC5A FC5B FC5C FC5D FC5E FC5F FC60-6F Electron Serial controller ================================== 6850 ACIA Serial controller --------------------------- FC60 6850 Control 6850 Status FC61 6850 Data 6850 Data FC62 FC63 FC64 FC65 FC66 FC67 FC68 FC69 FC6A FC6B FC6C FC6D FC6E FC6F FC60-6F Additional/External Serial ports ======================================== FC60 Port 1 6850 Control Port 1 6850 Status1 FC61 Port 1 6850 Data Port 1 6850 Data FC62 Port 1 baud rate control FC63 FC64 Port 2 6850 Control Port 2 6850 Status1 FC65 Port 2 6850 Data Port 2 6850 Data FC66 Port 2 baud rate control FC67 FC68 Port 3 6850 Control Port 3 6850 Status1 FC69 Port 3 6850 Data Port 3 6850 Data FC6A Port 3 baud rate control FC6B FC6C Port 4 6850 Control Port 4 6850 Status1 FC6D Port 4 6850 Data Port 4 6850 Data FC6E Port 4 baud rate control FC6F FC70-73 Electron expansion ========================== FC70 AtoD convertor FC71 Centronics parallel data FC72 Status FC73 FC74 FC75 FC76 FC77 FC78 FC79 FC7A FC7B FC7C FC7D FC7E FC7F FC80-87 LCD Display Control =========================== FC80 LCD Bank 0 Control LCD Bank 0 Status FC81 LCD Bank 0 Data LCD Bank 0 Data FC82 LCD Bank 1 Control LCD Bank 1 Status FC83 LCD Bank 1 Data LCD Bank 1 Data FC84 LCD Bank 2 Control LCD Bank 2 Status FC85 LCD Bank 2 Data LCD Bank 2 Data FC86 LCD Bank 3 Control LCD Bank 3 Status FC87 LCD Bank 3 Data LCD Bank 3 Data FC88 FC89 FC8A FC8B FC8C FC8D FC8E FC8F FC90-9F Electron sound and speech ================================= FC90 FC91 FC92 FC93 FC94 FC95 FC96 FC97 FC98 FC99 FC9A FC9B FC9C FC9D FC9E FC9F FCA0 FCA1 FCA2 FCA3 FCA4 FCA5 FCA6 FCA7 FCA8 FCA9 FCAA FCAB FCAC FCAD FCAE FCAF FCB0-BF Electron 6522 VIA expansion =================================== FCB0 Input register B Output register B FCB1 Input register A Output register A FCB2 Data direction register B Data direction register B FCB3 Data direction register A Data direction register A FCB4 T1 low-order counter T1 low-order latches FCB5 T1 high-order counter T1 high-order counter FCB6 T1 low-order latches T1 low-order latches FCB7 - T1 high-order latches FCB8 T2 low-order counter T2 low-order latches FCB9 T2 high order counter T2 high order counter FCBA Shift register Shift register FCBB Auxilary control register Auxilary control register FCBC Peripheral control register Peripheral control register FCBD Interupt flag register Interupt flag register FCBE Interupt enable register Interupt enable register FCBF Input register A, no handshake Output register A, no handshake FCC0-C3 Morley Electronics RAMdisc ================================== FCCC Bank Select b8-b15 - FCCD Bank Select b16-b23 - FCCE Bank Select b24-b31 - FCCF Control register - FCC0-CF Electron floppy disk expansion ====================================== 1770 floppy disk controller --------------------------- FCC0 Control port FCC1 FCC2 FCC3 FCC4 1770 Command Register 1770 Status Register FCC5 1770 Track register 1770 Track register FCC6 1770 Sector Register 1770 Sector register FCC7 1770 Data Register 1770 Data register FCC8 FCC9 FCCA FCCB FCCC FCCD FCCE FCCF FCC0 Electron digital joystick option C (see also FCD0) ========================================================== FCC0 Joystick state FCD0 Electron digital joystick option D ========================================== FCD0 Joystick state FCD0 FCD1 FCD2 FCD3 FCD4 FCD5 FCD6 FCD7 FCD8 FCD9 FCDA FCDB FCDC-DF PRES Advanced Battery-Backed RAM ======================================== FCDC Unlock RAM 0/2 FCDD Lock RAM 0/2 FCDE Unlock RAM 1/3 FCDF Lock RAM 1/3 FCE0-EF Electron Tube expansion =============================== FCE0 FCE1 FCE2 FCE3 FCE4 FCE5 Tube data transfer port Tube data transfer port FCE6 FCE7 FCE8 FCE9 FCEA FCEB FCEC FCED FCEE FCEF FCE0 Electron digital joystick option E (see also FCD0) ========================================================== FCE0 Joystick state FCF0-F7 JGH/ETI/EE/EMR MIDI Interface (see also FC08) ===================================================== FCF0 MIDI Port 1 6850 Control MIDI Port 1 6850 Status FCF1 MIDI Port 1 6850 Data MIDI Port 1 6850 Data FCF2 MIDI Port 2 6850 Control MIDI Port 2 6850 Status FCF3 MIDI Port 2 6850 Data MIDI Port 2 6850 Data FCF4 MIDI Port 3 6850 Control MIDI Port 3 6850 Status FCF5 MIDI Port 3 6850 Data MIDI Port 3 6850 Data FCF6 MIDI Port 4 6850 Control MIDI Port 4 6850 Status FCF7 MIDI Port 4 6850 Data MIDI Port 4 6850 Data FCF0 Electron digital joystick option F (see also FCD0) ========================================================== FCF0 Joystick state FCF8-F9 USB Port ================ FCF8 USB Data USB Data FCF9 USB Control USB Status FCFA-FD DataCentre non-volatile RAM control =========================================== FCFA NVRAM Data NVRAM Data FCFB NVRAM Data Direction Register FCFC NVRAM Data Strobe FCFC-FF Electron Advanced Quarter Meg RAM ========================================= FCFC Bank select FCFD Write protect AQR FCFE Disable write protect to AQR FCFC-FF Page-Wide Expansion RAM =============================== FCFC Bank Select b32-b39 - FCFD Bank Select b24-b31 - FCFE Bank Select b16-b23 - FCFF Bank Select b8-b15 -