BBC Microcomputer Service Manual Oct 1985 Section 1 BBC Micro ...

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170 !(&3200 + offset%) = &4433283F 180 !(&3204 + offset%) = &1B19021E 190 !(&3208 + offset%) = &13721293 200 !(&320C + offset%) = &002C002C 210 ENDPROC 220 230 DEFPROC strobe select lines 240 [OPT opt% 250 260 .loop 270 LDA &FE00 \ IC2 pin 25 (CRTC) 280 LDA &FE08 \ IC4 pin 9 (ACIA) 290 LDA &FE10 \ IC7 pin 9 (SER PROC) 300 LDA &FE18 \ IC96 pin 1 (STATID) or IC97 pin 4 (INTOFF) 310 LDA &FE20 \ IC97 pin 2 (INTON) 320 STA &FE20 \ IC6 pin 3 (VID PROC) 330 STA &FE30 \ IC76 pin 9 -(ROMSEL) 340 LDA &FE40 \ IC3 pin 23 (VIA A) 350 LDA &FE60 \ IC69 pin 23 (VIA B) 360 LDA &FE80 \ IC78 pin 24 (FDC) 370 LDA &FEAO \ IC89 pin 9 (ADLC) 380 LDA &FECO \ IC73 pin 23 (ADC) 390 LDA &FEE0 \ PL 12 pin 8 (TUBE) 400 LDA &FC00 \ PL 11 pin 10 (FRED) 410 LDA &FD00 \ PL 11 pin 12 (JIM) 420 JMP loop 430 ] 440 ENDPROC 450 460 DEFPROC DRAM test 470 [OPTopt% 480 LDX £&OF 490 STX &FE20 \ Write to Vidproc 500 510 .setup_6845 520 LDA table%,X \ table of 6845 data 530 STX &FE00 \ Register number 540 STA &FE01 \ Contents of register 550 DEX 560 BPL setup_6845 570 LDA £3 580 STA &FEFE \ send down TUBE 590 600 .restart 610 LDY £0 620 630 .loop2 640 NOP 650 TYA 660 STA &7C00,Y 670 STA &7D00,Y 680 STA &7E00,Y 690 STA &7F00,Y 700 INY 710 BNE loop2 720 730 LDA £&42 740 STA &FE20 \ Write to Vidproc 750 JMP restart 760 ] 48
770 ENDPROC 780 790 DEFPROC_RNW_exercise 800 810 [OPT opt% 820 LDX £&0F 830 STX &FE20 \ Write to Vidproc 840 850 .setup 6845 860 LDA table%,X \ table of 6845 data 870 STX &FE00 \ Register number 880 STA &FE01 \ Contents of register 890 DEX 900 BPL setup_6845 910 920 LDA £3 930 STA &FEFE \ send down TUBE 940 950 LDA £&41 \ Character "A" 960 LDY £0 970 980 .write 990 INC &7C01 \ Change character on screen 1000 STA &7D00,Y 1010 STA &7E00,Y 1020 STA &7F00,Y 1030 INY 1040 BNE write 1050 1060 LDA £&42 \ Character "B" 1070 STA &FE20 \ Write to Vidproc 1080 JMP write 1090 ] 1100 ENDPROC The following is a reproduction of a photograph showing the waveform on pin 34 of the 6502 (R/W of IC1). Scope parameters are 1V/cm, 2us/cm. 49
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BBC Microcomputer service manual SE
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SECTION 1 BBC Microcomputer Models
Page 8 and 9: 6 - Servicing + Fault-finding 6.1 I
Page 11 and 12: 1 Introduction 1.1 Nature and Purpo
Page 13 and 14: 1.2.2 Model B Specification The Mod
Page 15 and 16: 1.2.6 BASIC The BASIC interpreter i
Page 17 and 18: In the other screen modes, the info
Page 19 and 20: 3. Detailed Circuit Description 3.1
Page 22 and 23: 3.3 CRT controller + video processo
Page 24 and 25: The row address strobe signal is pr
Page 26 and 27: The speed of printing on the screen
Page 28 and 29: The CRTC is still used to generate
Page 30 and 31: is also determined by the control r
Page 32 and 33: 3.9 A to D convertors A four channe
Page 34 and 35: 3.13 1 MHz bus The address and data
Page 36 and 37: ii) Insert the above ICs into the s
Page 38 and 39: Edge connector pin number |6|7|8|9|
Page 40 and 41: R39-100k R47-1k5 R61-1k0 ii) Solder
Page 42 and 43: 10. WEST selects 5 1/4" disc. EAST
Page 44 and 45: 32. WEST selects A 13 input to pin
Page 46 and 47: 5.3 Circuit Modifications from issu
Page 48 and 49: 6 Servicing and Fault-finding 6.1 I
Page 50 and 51: iii) Check for the presence of the
Page 52 and 53: * On a number of occasions, the tra
Page 54 and 55: 6.5 Test programs and sample wavefo
Page 56 and 57: The 'following shows two more trace
Page 60 and 61: 7 Interfacing Survey 7.1 Purpose of
Page 62 and 63: The other way in which the RS423 ca
Page 64 and 65: The 20-way User Port is much simple
Page 66 and 67: 8 Component location tables The fol
Page 68 and 69: 8,2 Transistors Q Type Circuit Diag
Page 70 and 71: 8,5 Resistors R Value Circuit Diagr
Page 72 and 73: 116 3k9 14,2 117 2k2 14,2 118 1k0 1
Page 74 and 75: 6 4
Page 91 and 92: 9.8 Parts list CASE LOWER ASSEMBLY
Page 93 and 94: 65 631,047 CAPACITOR 47pF PLATE CER
Page 95 and 96: 9.9 Glossary of abbreviations ACK A
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