The latest version of the Speedlock group, again hacked to help you get on with the Pokes. Don't try running it on it's own though: because you'll only get an 'Out of data' message: you need to bolt on the game data for hacking the game into line 520 onwards...
Speedlock was the first and most common commercial turbo loader to be ever used on the ZX Spectrum. It was used in hundreds of ZX-Spectrum games, many of which were released by Ocean software. Although there are several revisions of the Speedlock, in the later releases, you can recognize it because the loading screen appears suddenly, there are no coloured stripes in the border whilst loading, and when the loading screen has appeared, there is often a countdown timer showing the remaining time expressed minutes, seconds and tenths of a second. Speedlock version one was the first turboloader to ever appear on the ZX Spectrum and was first developed in 1983. It was not however used commerically until October 1984, when it was used on 'Daley Thompson's Decathlon' which was released by Ocean software, by which time it had reached it's third version. Speedlock was first developed by David Looker and David-Aubrey-Jones (see left inset picture) who also wrote Mercenary for the ZX Spectrum. Further revisions of the Speedlock soon followed. The first type one Speedlocks were completely different to the later releases. They used the same initaliation routine, but a completely standard decrypter. The only differences between the type one Speedlock and an ordinary decrypting loader were it's initialisation routine and it's use of the IY register.
There were seven different versions of Speedlock, plus a hybrid one, although if David wrote all of these is unknown. It should be noted I can only find one game which uses Speedlock 7, and that was Repton 1 which was released by Aligator Software. I can find no reference to any game which uses Speedlock 6, which seems unusual. An interesting piece of history is that David secretly hid a message in his Speedlock one loader which reads "Government Health Warning - Attempting to crack Speedlock can seriously damage your Sanity!" Spectrum hackers attempted to hack the protection system, but it took an experienced and competent hacker who had a good understanding in Z80 assembler language to disassemble and to crack the Speedlock! The main reason why the Speedlock protection system was developed was to reduce the amount of software piracy because a loading system which loaded at over 150% above normal speed would not copy very reliably if a software pirate copied it many times over via a hifi system from cassette to cassette. It was also developed to reduce the loading times of commerical ZX Spectrum games (Speedlock 2 would load a game nearly 150% faster than normal), to keep out any hackers, and to save money (A cassette with a turboloader would load faster, hence the software company would require less cassette tape than was originally needed!). No doubt David made a substantial sum for his idea!
Examples: Out run, Ping Pong, Winter games 1 and 2, Madballs.
Click here to download this hacker (TAP format) or Click here to download this hacker (TZX format).
10 CLEAR : LET t=0
20 FOR f=23296 TO 23487
30 READ a : POKE f,a
40 LET t=t+(f-23286) * a : NEXT f
50 IF t<>2260540 THEN STOP
60 FOR f=f TO 1e9 : READ a
70 IF a>255 THEN GOTO 100
80 POKE f,a
90 LET t=t+(f-23478) * a : NEXT f
100 IF t<>a THEN STOP
110 PRINT "Type CONTINUE"
120 STOP : RANDOMIZE USR 23296
130 DATA 221,42,192,91,237
140 DATA 91,194,91,62,255
150 DATA 55,205,86,5,48
160 DATA 240,243,33,201,91
170 DATA 17,106,89,1,3
180 DATA 0,237,176,237,75
190 DATA 197,91,14,0,237
200 DATA 67,109,76,237,75
210 DATA 198,91,253,42,196
220 DATA 91,14,0,237,67
230 DATA 111,76,253,78,0
240 DATA 6,0,42,106,89
250 DATA 34,113,89,9,94
260 DATA 54,84,35,86,54
270 DATA 91,237,83,106,89
280 DATA 42,113,89,58,108
290 DATA 89,237,79,233,237
300 DATA 95,214,3,254,250
310 DATA 56,2,214,128,50
320 DATA 108,89,253,35,237
330 DATA 75,111,76,16,199
340 DATA 237,75,109,76,16
350 DATA 179,58,200,91,71
360 DATA 33,24,16,34,105
370 DATA 91,24,175,33,145
380 DATA 91,34,230,254,175
390 DATA 50,183,251,195,126
400 DATA 251,1,96,54,82
410 DATA 50,17,14,12,24
420 DATA 205,64,254,33,181
430 DATA 91,34,65,254,17
440 DATA 170,91,33,70,254
450 DATA 1,11,0,34,232
460 DATA 253,235,237,176,201
470 DATA 229,33,0,72,34
480 DATA 108,255,225,195,42
490 DATA 254,42,204,91,54
500 DATA 206,35,54,91,195
510 DATA 0,72
