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PRACT/TEXT1
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/TEXT1 |
| Read OK: | ✔ |
| File size: | 0520 bytes |
| Load address: | 450D |
| Exec address: | 5845 |
File contents
TAB & SHIFT LOCK KEYS
~~~~~~~~~~~~~~~~~~~~~
By D. Walker
~~~~~~~~~~~~
Why did Acorn not put a TAB key on the Electron? and why was the SHIFT
LOCK key left off too? It's not as if there wasn't enough room to
accommodate these useful keys - either mechanically or electronically.
To rectify this oversight I have designed a couple of circuits, one to
simulate the TAB by using the <CTRL> <I> key sequence and the other to to
toggle the <SHIFT> "on" and "off".
TAB
~~~
My design remit was to use a single key to simulate the <CTRL> <I>
sequence to produce a TAB character in a wordprocessor.
The first part of the design was to determine the sequence of events:
Press CTRL -> Press I -> Release I -> Release CTRL
This translates into the electrical waveform:
______________________________
______: :___________ CTRL
:<-----------"t1"------------->:
____________
____________________: :________________ I
:<---"d1"---->:<---"t2"--->:
The circuit has to produce two outputs, CTRL & I, whose waveforms have the
above relationship. This is achieved with the following circuits:
00000000 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000010 20 20 20 20 20 54 41 42 20 26 20 53 48 49 46 54 | TAB & SHIFT| 00000020 20 4c 4f 43 4b 20 4b 45 59 53 20 0d 20 20 20 20 | LOCK KEYS . | 00000030 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000040 20 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e | ~~~~~~~~~~~~~~~| 00000050 7e 7e 7e 7e 7e 7e 20 0d 20 0d 20 20 20 20 20 20 |~~~~~~ . . | 00000060 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000070 20 20 20 42 79 20 44 2e 20 57 61 6c 6b 65 72 20 | By D. Walker | 00000080 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000090 20 20 20 20 20 20 20 20 20 20 7e 7e 7e 7e 7e 7e | ~~~~~~| 000000a0 7e 7e 7e 7e 7e 7e 20 0d 20 0d 57 68 79 20 64 69 |~~~~~~ . .Why di| 000000b0 64 20 41 63 6f 72 6e 20 6e 6f 74 20 70 75 74 20 |d Acorn not put | 000000c0 61 20 54 41 42 20 6b 65 79 20 6f 6e 20 74 68 65 |a TAB key on the| 000000d0 20 45 6c 65 63 74 72 6f 6e 3f 20 61 6e 64 20 77 | Electron? and w| 000000e0 68 79 20 77 61 73 20 74 68 65 20 53 48 49 46 54 |hy was the SHIFT| 000000f0 20 0d 4c 4f 43 4b 20 6b 65 79 20 6c 65 66 74 20 | .LOCK key left | 00000100 6f 66 66 20 74 6f 6f 3f 20 20 49 74 27 73 20 6e |off too? It's n| 00000110 6f 74 20 61 73 20 69 66 20 74 68 65 72 65 20 77 |ot as if there w| 00000120 61 73 6e 27 74 20 65 6e 6f 75 67 68 20 72 6f 6f |asn't enough roo| 00000130 6d 20 74 6f 20 0d 61 63 63 6f 6d 6d 6f 64 61 74 |m to .accommodat| 00000140 65 20 74 68 65 73 65 20 75 73 65 66 75 6c 20 6b |e these useful k| 00000150 65 79 73 20 2d 20 65 69 74 68 65 72 20 6d 65 63 |eys - either mec| 00000160 68 61 6e 69 63 61 6c 6c 79 20 6f 72 20 65 6c 65 |hanically or ele| 00000170 63 74 72 6f 6e 69 63 61 6c 6c 79 2e 20 0d 20 0d |ctronically. . .| 00000180 54 6f 20 72 65 63 74 69 66 79 20 74 68 69 73 20 |To rectify this | 00000190 6f 76 65 72 73 69 67 68 74 20 49 20 68 61 76 65 |oversight I have| 000001a0 20 64 65 73 69 67 6e 65 64 20 61 20 63 6f 75 70 | designed a coup| 000001b0 6c 65 20 6f 66 20 63 69 72 63 75 69 74 73 2c 20 |le of circuits, | 000001c0 6f 6e 65 20 74 6f 20 0d 73 69 6d 75 6c 61 74 65 |one to .simulate| 000001d0 20 74 68 65 20 54 41 42 20 62 79 20 75 73 69 6e | the TAB by usin| 000001e0 67 20 74 68 65 20 3c 43 54 52 4c 3e 20 3c 49 3e |g the <CTRL> <I>| 000001f0 20 6b 65 79 20 73 65 71 75 65 6e 63 65 20 61 6e | key sequence an| 00000200 64 20 74 68 65 20 6f 74 68 65 72 20 74 6f 20 74 |d the other to t| 00000210 6f 20 0d 74 6f 67 67 6c 65 20 74 68 65 20 3c 53 |o .toggle the <S| 00000220 48 49 46 54 3e 20 22 6f 6e 22 20 61 6e 64 20 22 |HIFT> "on" and "| 00000230 6f 66 66 22 2e 20 0d 20 0d 20 0d 54 41 42 20 0d |off". . . .TAB .| 00000240 7e 7e 7e 20 0d 4d 79 20 64 65 73 69 67 6e 20 72 |~~~ .My design r| 00000250 65 6d 69 74 20 77 61 73 20 74 6f 20 75 73 65 20 |emit was to use | 00000260 61 20 73 69 6e 67 6c 65 20 6b 65 79 20 74 6f 20 |a single key to | 00000270 73 69 6d 75 6c 61 74 65 20 74 68 65 20 3c 43 54 |simulate the <CT| 00000280 52 4c 3e 20 3c 49 3e 20 0d 73 65 71 75 65 6e 63 |RL> <I> .sequenc| 00000290 65 20 74 6f 20 70 72 6f 64 75 63 65 20 61 20 54 |e to produce a T| 000002a0 41 42 20 63 68 61 72 61 63 74 65 72 20 69 6e 20 |AB character in | 000002b0 61 20 77 6f 72 64 70 72 6f 63 65 73 73 6f 72 2e |a wordprocessor.| 000002c0 20 0d 20 0d 54 68 65 20 66 69 72 73 74 20 70 61 | . .The first pa| 000002d0 72 74 20 6f 66 20 74 68 65 20 64 65 73 69 67 6e |rt of the design| 000002e0 20 77 61 73 20 74 6f 20 64 65 74 65 72 6d 69 6e | was to determin| 000002f0 65 20 74 68 65 20 73 65 71 75 65 6e 63 65 20 6f |e the sequence o| 00000300 66 20 65 76 65 6e 74 73 3a 20 0d 20 0d 50 72 65 |f events: . .Pre| 00000310 73 73 20 43 54 52 4c 20 2d 3e 20 50 72 65 73 73 |ss CTRL -> Press| 00000320 20 49 20 2d 3e 20 52 65 6c 65 61 73 65 20 49 20 | I -> Release I | 00000330 2d 3e 20 52 65 6c 65 61 73 65 20 43 54 52 4c 20 |-> Release CTRL | 00000340 0d 20 0d 54 68 69 73 20 74 72 61 6e 73 6c 61 74 |. .This translat| 00000350 65 73 20 69 6e 74 6f 20 74 68 65 20 65 6c 65 63 |es into the elec| 00000360 74 72 69 63 61 6c 20 77 61 76 65 66 6f 72 6d 3a |trical waveform:| 00000370 20 0d 20 0d 20 20 20 20 20 20 20 20 20 5f 5f 5f | . . ___| 00000380 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f |________________| 00000390 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 20 0d 20 20 5f |___________ . _| 000003a0 5f 5f 5f 5f 5f 3a 20 20 20 20 20 20 20 20 20 20 |_____: | 000003b0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000003c0 20 20 20 20 3a 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f | :___________| 000003d0 20 20 20 43 54 52 4c 20 0d 20 0d 20 20 20 20 20 | CTRL . . | 000003e0 20 20 20 3a 3c 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d | :<-----------| 000003f0 22 74 31 22 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |"t1"------------| 00000400 2d 3e 3a 20 0d 20 20 20 20 20 20 20 20 20 20 20 |->: . | 00000410 20 20 20 20 20 20 20 20 20 20 20 20 5f 5f 5f 5f | ____| 00000420 5f 5f 5f 5f 5f 5f 5f 5f 20 0d 20 20 5f 5f 5f 5f |________ . ____| 00000430 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f |________________| 00000440 3a 20 20 20 20 20 20 20 20 20 20 20 20 3a 5f 5f |: :__| 00000450 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 20 20 |______________ | 00000460 20 49 20 0d 20 0d 20 20 20 20 20 20 20 20 3a 3c | I . . :<| 00000470 2d 2d 2d 22 64 31 22 2d 2d 2d 2d 3e 3a 3c 2d 2d |---"d1"---->:<--| 00000480 2d 22 74 32 22 2d 2d 2d 3e 3a 20 0d 20 0d 20 0d |-"t2"--->: . . .| 00000490 54 68 65 20 63 69 72 63 75 69 74 20 68 61 73 20 |The circuit has | 000004a0 74 6f 20 70 72 6f 64 75 63 65 20 74 77 6f 20 6f |to produce two o| 000004b0 75 74 70 75 74 73 2c 20 43 54 52 4c 20 26 20 49 |utputs, CTRL & I| 000004c0 2c 20 77 68 6f 73 65 20 77 61 76 65 66 6f 72 6d |, whose waveform| 000004d0 73 20 68 61 76 65 20 74 68 65 20 0d 61 62 6f 76 |s have the .abov| 000004e0 65 20 72 65 6c 61 74 69 6f 6e 73 68 69 70 2e 20 |e relationship. | 000004f0 20 54 68 69 73 20 69 73 20 61 63 68 69 65 76 65 | This is achieve| 00000500 64 20 77 69 74 68 20 74 68 65 20 66 6f 6c 6c 6f |d with the follo| 00000510 77 69 6e 67 20 63 69 72 63 75 69 74 73 3a 20 0d |wing circuits: .| 00000520
PRACT/TEXT1.m0
PRACT/TEXT1.m1
PRACT/TEXT1.m2
PRACT/TEXT1.m4
PRACT/TEXT1.m5
.