Home » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_17.ADF » PRACT/TEXT2
PRACT/TEXT2
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_17.ADF |
| Filename: | PRACT/TEXT2 |
| Read OK: | ✔ |
| File size: | 07A1 bytes |
| Load address: | 450D |
| Exec address: | 5845 |
File contents
OPERATION ~~~~~~~~~ Pressing and releasing S2 triggers IC3b (a retriggerable monostable) immediately which in turn switches on IC2b (a bilateral switch), which effectively closes the CTRL keyswitch for 300mS (t1). When IC3b is triggered, R6/C2 delays the trigger of IC3a for 150mS (d1). After the 150mS delay IC2a switches on, effectively closing the I keyswitch for 75mS (t2). R6/C2 also debounces the S2. IC2a pins 10 & 11 are wired to the "CTRL" keyswitch and IC2b pins 1 & 2 are wired to the "I" keyswitch on the keyboard. SHIFT LOCK ~~~~~~~~~~ IC1 (a D type flip flop) is configured to toggle its output once for every clock pulse it receives. The clock pulse is generated by S1 which is debounced by R1/C1. The Q output of IC1 is used to switch on an LED to indicate that the SHIFT LOCK is "on" or "off" and to switch IC2c, another bilateral switch to effectively latch open or close the SHIFT keyswitch. IC2c pins 3 & 4 are wired to the SHIFT key on the keyboard. CONSTRUCTION ~~~~~~~~~~~~ The construction of the circuit was done on Vero board but a circuit board could quite easily be designed and produced. The boards mounting will depend on your system, I mounted the circuit on the left hand side of the keyboard next to the SHIFT and CTRL keys - this space is only available to those who have moved their Electron circuit board into a Slogger RX case or similar box. It could be mounted somewhere behind the function keys or alternatively in a separate box. Parts List R1 15K 0.25W C1 10uF 16V IC1 74LS74 R2 4K7 " C2 10uF 16V IC2 CD4538 R3 470R " C3 22uF 16V IC3 74C4066 R4 47K " C4 4.7uF 16V R5 2K2 " R6 15K " Q1 BC107 SW1,2 Keyswitch R7 15K " D1 OA91 R8 15K " LED1 RED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
00000000 4f 50 45 52 41 54 49 4f 4e 20 0d 7e 7e 7e 7e 7e |OPERATION .~~~~~| 00000010 7e 7e 7e 7e 20 0d 20 0d 50 72 65 73 73 69 6e 67 |~~~~ . .Pressing| 00000020 20 61 6e 64 20 72 65 6c 65 61 73 69 6e 67 20 53 | and releasing S| 00000030 32 20 74 72 69 67 67 65 72 73 20 49 43 33 62 20 |2 triggers IC3b | 00000040 28 61 20 72 65 74 72 69 67 67 65 72 61 62 6c 65 |(a retriggerable| 00000050 20 6d 6f 6e 6f 73 74 61 62 6c 65 29 20 0d 69 6d | monostable) .im| 00000060 6d 65 64 69 61 74 65 6c 79 20 77 68 69 63 68 20 |mediately which | 00000070 69 6e 20 74 75 72 6e 20 73 77 69 74 63 68 65 73 |in turn switches| 00000080 20 6f 6e 20 49 43 32 62 20 28 61 20 62 69 6c 61 | on IC2b (a bila| 00000090 74 65 72 61 6c 20 73 77 69 74 63 68 29 2c 20 77 |teral switch), w| 000000a0 68 69 63 68 20 0d 65 66 66 65 63 74 69 76 65 6c |hich .effectivel| 000000b0 79 20 63 6c 6f 73 65 73 20 74 68 65 20 43 54 52 |y closes the CTR| 000000c0 4c 20 6b 65 79 73 77 69 74 63 68 20 66 6f 72 20 |L keyswitch for | 000000d0 33 30 30 6d 53 20 28 74 31 29 2e 20 0d 20 0d 57 |300mS (t1). . .W| 000000e0 68 65 6e 20 49 43 33 62 20 69 73 20 74 72 69 67 |hen IC3b is trig| 000000f0 67 65 72 65 64 2c 20 52 36 2f 43 32 20 64 65 6c |gered, R6/C2 del| 00000100 61 79 73 20 74 68 65 20 74 72 69 67 67 65 72 20 |ays the trigger | 00000110 6f 66 20 49 43 33 61 20 66 6f 72 20 31 35 30 6d |of IC3a for 150m| 00000120 53 20 28 64 31 29 2e 20 20 0d 41 66 74 65 72 20 |S (d1). .After | 00000130 74 68 65 20 31 35 30 6d 53 20 64 65 6c 61 79 20 |the 150mS delay | 00000140 49 43 32 61 20 73 77 69 74 63 68 65 73 20 6f 6e |IC2a switches on| 00000150 2c 20 65 66 66 65 63 74 69 76 65 6c 79 20 63 6c |, effectively cl| 00000160 6f 73 69 6e 67 20 74 68 65 20 49 20 0d 6b 65 79 |osing the I .key| 00000170 73 77 69 74 63 68 20 66 6f 72 20 37 35 6d 53 20 |switch for 75mS | 00000180 28 74 32 29 2e 20 20 52 36 2f 43 32 20 61 6c 73 |(t2). R6/C2 als| 00000190 6f 20 64 65 62 6f 75 6e 63 65 73 20 74 68 65 20 |o debounces the | 000001a0 53 32 2e 20 20 0d 20 0d 49 43 32 61 20 70 69 6e |S2. . .IC2a pin| 000001b0 73 20 31 30 20 26 20 31 31 20 61 72 65 20 77 69 |s 10 & 11 are wi| 000001c0 72 65 64 20 74 6f 20 74 68 65 20 22 43 54 52 4c |red to the "CTRL| 000001d0 22 20 6b 65 79 73 77 69 74 63 68 20 61 6e 64 20 |" keyswitch and | 000001e0 49 43 32 62 20 70 69 6e 73 20 31 20 26 20 32 20 |IC2b pins 1 & 2 | 000001f0 0d 61 72 65 20 77 69 72 65 64 20 74 6f 20 74 68 |.are wired to th| 00000200 65 20 22 49 22 20 6b 65 79 73 77 69 74 63 68 20 |e "I" keyswitch | 00000210 6f 6e 20 74 68 65 20 6b 65 79 62 6f 61 72 64 2e |on the keyboard.| 00000220 20 0d 20 0d 0d 53 48 49 46 54 20 4c 4f 43 4b 20 | . ..SHIFT LOCK | 00000230 0d 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 20 0d 20 0d 49 |.~~~~~~~~~~ . .I| 00000240 43 31 20 28 61 20 44 20 74 79 70 65 20 66 6c 69 |C1 (a D type fli| 00000250 70 20 66 6c 6f 70 29 20 69 73 20 63 6f 6e 66 69 |p flop) is confi| 00000260 67 75 72 65 64 20 74 6f 20 74 6f 67 67 6c 65 20 |gured to toggle | 00000270 69 74 73 20 6f 75 74 70 75 74 20 6f 6e 63 65 20 |its output once | 00000280 66 6f 72 20 65 76 65 72 79 20 0d 63 6c 6f 63 6b |for every .clock| 00000290 20 70 75 6c 73 65 20 69 74 20 72 65 63 65 69 76 | pulse it receiv| 000002a0 65 73 2e 20 20 54 68 65 20 63 6c 6f 63 6b 20 70 |es. The clock p| 000002b0 75 6c 73 65 20 69 73 20 67 65 6e 65 72 61 74 65 |ulse is generate| 000002c0 64 20 62 79 20 53 31 20 77 68 69 63 68 20 69 73 |d by S1 which is| 000002d0 20 0d 64 65 62 6f 75 6e 63 65 64 20 62 79 20 52 | .debounced by R| 000002e0 31 2f 43 31 2e 20 20 54 68 65 20 51 20 6f 75 74 |1/C1. The Q out| 000002f0 70 75 74 20 6f 66 20 49 43 31 20 69 73 20 75 73 |put of IC1 is us| 00000300 65 64 20 74 6f 20 73 77 69 74 63 68 20 6f 6e 20 |ed to switch on | 00000310 61 6e 20 4c 45 44 20 74 6f 20 0d 69 6e 64 69 63 |an LED to .indic| 00000320 61 74 65 20 74 68 61 74 20 74 68 65 20 53 48 49 |ate that the SHI| 00000330 46 54 20 4c 4f 43 4b 20 69 73 20 22 6f 6e 22 20 |FT LOCK is "on" | 00000340 6f 72 20 22 6f 66 66 22 20 61 6e 64 20 74 6f 20 |or "off" and to | 00000350 73 77 69 74 63 68 20 49 43 32 63 2c 20 61 6e 6f |switch IC2c, ano| 00000360 74 68 65 72 20 0d 62 69 6c 61 74 65 72 61 6c 20 |ther .bilateral | 00000370 73 77 69 74 63 68 20 74 6f 20 65 66 66 65 63 74 |switch to effect| 00000380 69 76 65 6c 79 20 6c 61 74 63 68 20 6f 70 65 6e |ively latch open| 00000390 20 6f 72 20 63 6c 6f 73 65 20 74 68 65 20 53 48 | or close the SH| 000003a0 49 46 54 20 6b 65 79 73 77 69 74 63 68 2e 20 0d |IFT keyswitch. .| 000003b0 20 0d 49 43 32 63 20 70 69 6e 73 20 33 20 26 20 | .IC2c pins 3 & | 000003c0 34 20 61 72 65 20 77 69 72 65 64 20 74 6f 20 74 |4 are wired to t| 000003d0 68 65 20 53 48 49 46 54 20 6b 65 79 20 6f 6e 20 |he SHIFT key on | 000003e0 74 68 65 20 6b 65 79 62 6f 61 72 64 2e 20 0d 20 |the keyboard. . | 000003f0 0d 20 0d 43 4f 4e 53 54 52 55 43 54 49 4f 4e 20 |. .CONSTRUCTION | 00000400 0d 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 20 0d 20 |.~~~~~~~~~~~~ . | 00000410 0d 54 68 65 20 63 6f 6e 73 74 72 75 63 74 69 6f |.The constructio| 00000420 6e 20 6f 66 20 74 68 65 20 63 69 72 63 75 69 74 |n of the circuit| 00000430 20 77 61 73 20 64 6f 6e 65 20 6f 6e 20 56 65 72 | was done on Ver| 00000440 6f 20 62 6f 61 72 64 20 62 75 74 20 61 20 63 69 |o board but a ci| 00000450 72 63 75 69 74 20 62 6f 61 72 64 20 0d 63 6f 75 |rcuit board .cou| 00000460 6c 64 20 71 75 69 74 65 20 65 61 73 69 6c 79 20 |ld quite easily | 00000470 62 65 20 64 65 73 69 67 6e 65 64 20 61 6e 64 20 |be designed and | 00000480 70 72 6f 64 75 63 65 64 2e 20 20 54 68 65 20 62 |produced. The b| 00000490 6f 61 72 64 73 20 6d 6f 75 6e 74 69 6e 67 20 77 |oards mounting w| 000004a0 69 6c 6c 20 0d 64 65 70 65 6e 64 20 6f 6e 20 79 |ill .depend on y| 000004b0 6f 75 72 20 73 79 73 74 65 6d 2c 20 49 20 6d 6f |our system, I mo| 000004c0 75 6e 74 65 64 20 74 68 65 20 63 69 72 63 75 69 |unted the circui| 000004d0 74 20 6f 6e 20 74 68 65 20 6c 65 66 74 20 68 61 |t on the left ha| 000004e0 6e 64 20 73 69 64 65 20 6f 66 20 74 68 65 20 0d |nd side of the .| 000004f0 6b 65 79 62 6f 61 72 64 20 6e 65 78 74 20 74 6f |keyboard next to| 00000500 20 74 68 65 20 53 48 49 46 54 20 61 6e 64 20 43 | the SHIFT and C| 00000510 54 52 4c 20 6b 65 79 73 20 2d 20 74 68 69 73 20 |TRL keys - this | 00000520 73 70 61 63 65 20 69 73 20 6f 6e 6c 79 20 61 76 |space is only av| 00000530 61 69 6c 61 62 6c 65 20 74 6f 20 0d 74 68 6f 73 |ailable to .thos| 00000540 65 20 77 68 6f 20 68 61 76 65 20 6d 6f 76 65 64 |e who have moved| 00000550 20 74 68 65 69 72 20 45 6c 65 63 74 72 6f 6e 20 | their Electron | 00000560 63 69 72 63 75 69 74 20 62 6f 61 72 64 20 69 6e |circuit board in| 00000570 74 6f 20 61 20 53 6c 6f 67 67 65 72 20 52 58 20 |to a Slogger RX | 00000580 63 61 73 65 20 0d 6f 72 20 73 69 6d 69 6c 61 72 |case .or similar| 00000590 20 62 6f 78 2e 20 20 49 74 20 63 6f 75 6c 64 20 | box. It could | 000005a0 62 65 20 6d 6f 75 6e 74 65 64 20 73 6f 6d 65 77 |be mounted somew| 000005b0 68 65 72 65 20 62 65 68 69 6e 64 20 74 68 65 20 |here behind the | 000005c0 66 75 6e 63 74 69 6f 6e 20 6b 65 79 73 20 6f 72 |function keys or| 000005d0 20 0d 61 6c 74 65 72 6e 61 74 69 76 65 6c 79 20 | .alternatively | 000005e0 69 6e 20 61 20 73 65 70 61 72 61 74 65 20 62 6f |in a separate bo| 000005f0 78 2e 20 0d 20 0d 20 0d 50 61 72 74 73 20 4c 69 |x. . . .Parts Li| 00000600 73 74 20 0d 20 0d 52 31 20 20 20 31 35 4b 20 20 |st . .R1 15K | 00000610 30 2e 32 35 57 20 20 20 20 20 20 43 31 20 20 20 |0.25W C1 | 00000620 31 30 75 46 20 31 36 56 20 20 20 20 20 20 20 49 |10uF 16V I| 00000630 43 31 20 20 37 34 4c 53 37 34 20 0d 52 32 20 20 |C1 74LS74 .R2 | 00000640 20 34 4b 37 20 20 20 20 22 20 20 20 20 20 20 20 | 4K7 " | 00000650 20 43 32 20 20 20 31 30 75 46 20 31 36 56 20 20 | C2 10uF 16V | 00000660 20 20 20 20 20 49 43 32 20 20 43 44 34 35 33 38 | IC2 CD4538| 00000670 20 0d 52 33 20 20 20 34 37 30 52 20 20 20 22 20 | .R3 470R " | 00000680 20 20 20 20 20 20 20 43 33 20 20 20 32 32 75 46 | C3 22uF| 00000690 20 31 36 56 20 20 20 20 20 20 20 49 43 33 20 20 | 16V IC3 | 000006a0 37 34 43 34 30 36 36 20 0d 52 34 20 20 20 34 37 |74C4066 .R4 47| 000006b0 4b 20 20 20 20 22 20 20 20 20 20 20 20 20 43 34 |K " C4| 000006c0 20 20 20 34 2e 37 75 46 20 31 36 56 20 0d 52 35 | 4.7uF 16V .R5| 000006d0 20 20 20 32 4b 32 20 20 20 20 22 20 0d 52 36 20 | 2K2 " .R6 | 000006e0 20 20 31 35 4b 20 20 20 20 22 20 20 20 20 20 20 | 15K " | 000006f0 20 20 51 31 20 20 20 42 43 31 30 37 20 20 20 20 | Q1 BC107 | 00000700 20 20 20 20 20 20 53 57 31 2c 32 20 4b 65 79 73 | SW1,2 Keys| 00000710 77 69 74 63 68 20 0d 52 37 20 20 20 31 35 4b 20 |witch .R7 15K | 00000720 20 20 20 22 20 20 20 20 20 20 20 20 44 31 20 20 | " D1 | 00000730 20 4f 41 39 31 20 0d 52 38 20 20 20 31 35 4b 20 | OA91 .R8 15K | 00000740 20 20 20 22 20 20 20 20 20 20 20 20 4c 45 44 31 | " LED1| 00000750 20 52 45 44 20 0d 20 0d 20 0d 7e 7e 7e 7e 7e 7e | RED . . .~~~~~~| 00000760 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e |~~~~~~~~~~~~~~~~| * 000007a0 0d |.| 000007a1
PRACT/TEXT2.m0
PRACT/TEXT2.m1
PRACT/TEXT2.m2
PRACT/TEXT2.m4
PRACT/TEXT2.m5
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