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CPC Tape format

Started by ohamoha, 14:39, 23 August 13

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ohamoha

Hello guys.
A long time ago I had an Amstrad 464 which I loved. Unfortunately my dad gave it away to some child and I lost track. But searching through my old tapes I found some on which I've saved some programs. I would like to load them into an emulator (since my computer is lost). I've recorded some WAV files and I would like to extract the sources from them. Do you know where I can find some info on how to do that?
I can convert them to 1 and 0 but I don't know what to do from here.


Thank you very much.
Adrian

ralferoo

Try http://www.worldofspectrum.org/TZXGuide.pdf or indeed anything from World of Spectrum - Utilities

When you're done, just rename the spectrum .tzx file to .cdt and it should work in any Amstrad emulator. The CPC tape format is based on the speccy format as they're very similar and most of the Amstrad turbo loaders are really just spectrum turbo loaders in disguise!

ohamoha

Great! Thank you so much!  ;D

dcdrac

wow what do you have?

Cholo

Indeed, many spectrum tools really help converting Amstrad format tape. Sadly none of them (as far as i know) know how to handle the basic normal amstrad "Block" format. So you cant really get around getting some Amstrad specific tools .. at least for the "Blocks". As already mentioned: Spectrum TZX is the same as Amstrad CDT so all you really need to use one file in another tool is to quickly rename its extension and it works.

DosBox: a "old pc emulator". May be needed to run several of the better tools as they are old Dos programs and may need to run in wierd old modes with files like Dos4gw or mouse.com or similar.

Samp2cdt: Probably the best (most usefull) tool for all amstrad tape handling. Its commandline and supports a bunch of protections and situations. A must have.

CPCTapeXP 1.1: windows compatible. Can only do basic amstrad Block & Records to CDT, but it is quite userfriendly and the "CDT Studio" is extremely usefully for mergeing blocks/data etc.

Taper: spectrum audio-to-TZX tool. Extremely usefull as it recognizes a LOT of protections automaticly (including most amstrad ones .. even some that amstrad tools cant handle themselves).

Tapir: spectrum TZX "studio" tool. Really nice copy/paste TZX tool. Windows compatible makes it quite easy to merge data etc. Also does a nice TZX to WAV (may come in handy some other day).

UberCassette: Commandline. Audio-to-CDT but only your basic Amstrad Blocks.

CSW: Not only a very common compressed format but also supports a lot of audio formats. Can be used to "strengthen" amstrad block format.

A good audio capture program: I just happen to use Goldwave but you can use any tool you like.

Tips and tricks:

"strengthen blocks": Lets say you recorded a wav of something harmless unprotected like a Amsoft or Elite brand game that only has normal amstrad blocks. Alas the originally recording is "weak" so even your ol 464 is struggling to read it. Samp2cdt (or other tool) keeps having troubles reading it too? Try CSW-ing it .. aka translate from wav->csw->voc. And then Samp2cdt will probably read it much better. CSW-ing it basicly forces high signal to = high and low signal = low (or 1 or 0). Unlike if samp2cdt reads the source directly and get confused because it meets a 0,65 "high" signal and thinks its a 0. Donno if that made any sense  ;D
Oh, you can also do the dirty trick of copying the game using like Amsback/JL-copy from the old tape to a brand new tape and then use that for audio recording. The new tape will be crisp clear and not suffer from 25 year old "bad manufacturing".

"protected games for beginners": The way most protected games works is by first having a "loader", then a "gap" and finally a "protected" part. The "loader" at the start of the tape is ususally normal amstrad 1-3 blocks containing the code to be able to load the rest of the game.
The "Gap" is just a empty pause on the tape containing nothing .. the cause of the gap is simply as it takes time when the "loader" code is "de-coding" while the tape motor is still running. So its importent to note down the length of the "gap" .. aka 3 or 5 or 7 seconds. Wrong "gap" = loading crashes.
The "protected" part of the is usually where it get freakishly technical, however lets just say for now that its the part where the screens borders starts flashing when loading the odd sounding data.

Quick conversion of protected tape for beginners: To translate a protected game id start by exporting/cutting the audio file into "loader", write down the "gap" length and cut/export out the "protected" part as well. The "loader" id try converting with CPCTapeXP so you get blocks converted to like "loader.cdt". Probably a good idea to check if the "loader.cdt" works in your favorite emulator before proceeding. Then rename it "loader.tzx".
Use Taper "auto" to convert the "protected" audio part to like "protected.tzx".
Then finally merge everything in Tapir .. aka loader.tzx first, then make a empty gap with the correct length and finally add protected.tzx. Export to game.tzx and rename to game.cdt.

Into the deep end: Probably end up using Samp2cdt as its the most "flexible" of the tools. Samp2cdt has a alternate way of converting to CDT too. Lots of options to play with. This however also means it requires the most manual input from you. Just recognizing the protections can be quite hard sometimes (hint: lets say you want to convert a US.Gold 88' game .. then sneak a peek over at cpc-power at other US Gold 87-89' games as they probably used the same protection). Probably a good idea to make some batch (.bat) files to speed up things in Samp2cdt and similar commandline tools.

Preservation vs playability: Hang on there Clolo old buddy what all that with "strengthening" and copying and cutting and pasting .. doing that will clearly change the output to something different than the "factory" made original? Shouldnt you try to keeping the original "layout" as close as possible? Good question.
Take like the first Amstrad Action covertape with the game Kung Fu & Number 1 .. one of the games had a way too small gap between the loader and the following record = wouldnt load. So what is most importent .. preserving the original tape layout or being able to play the game in a emulator?
Personally i go for playablility. Once you start converting it to CDT it gets changed so much anyway and dont forget that even if you just though you made a perfect CDT .. it may still not load in many emulators. Dont forget you can still save all you old WAV files as well. Unlike the old days converting to CDT isnt no longer a space issue or internet issue anymore.

arnoldemu

Quote from: ohamoha on 16:15, 23 August 13
Great! Thank you so much!  ;D
Look at my website in the download section.

cpctech.org.uk

There are some tape tools which can be used to verify tape images with standard block and fast-loader. These check the blocks are formed correctly and the checksums are good.
My games. My Games
My website with coding examples: Unofficial Amstrad WWW Resource

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