Multi format/system tape load?

[matsondawson]

Given the systems below, could a single tape could be crafted to load a program successfully on all of them? I'm fairly sure the answer is no, but how close could you get?

FM formats:
Atari              3995Hz 5327Hz
CBM                1488Hz 1953Hz 2840Hz
ZX Spectrum        1000Hz 2000Hz
Apple 2             770Hz 1000Hz 2000Hz  2500Hz
TRS80, Acorn, BBC  1200Hz 2400Hz

On/Off formats:
Amstrad CPC464      500Hz
ZX80/ZX81          3200Hz

 

[vwestlife]

Do you mean simultaneously, or one after another? I'm pretty sure it would be impossible to record multiple formats simultaneously, because the different frequencies would intermodulate with each other and render the waveform too distorted to decode properly.

You certainly could record a tape with multiple formats, one after the other, but depending on how well each computer rejects and ignores a "foreign" data track, it may require fast-forwarding the tape to the correct track for the computer being used.

And along the same lines, I remember seeing a BASIC program which could be typed in and would work on either an Apple II or an IBM PC, depending on how a variable was set at the beginning of the program. Every time the program came to a statement that required different syntax for either the Apple or PC, it would do an IF/THEN on that variable to determine which statement to execute. Of course this wasted a lot of code and slowed down execution, but it was proof that it could be done.

 

[matsondawson]

I was thinking whatever technique gets all the programs off the tape the quickest, without a non-target computer dying.
I figure it's probably sequential as most of the tape decoders are zero crossing detectors, so merging any streams would be detrimental.
I think I really need to get all the computers mentioned and see which ones fail with which other ones streams.
Then hopefully there will be an order of streams that will work with all.

 

[carlsson]

I wonder as well. I looked up the Kansas City Standard a while ago. It defines signals according to baud rates, but I figure frequencies used must be just as important as the baud rate used. Then there is Basicode which is yet an abstraction layer on top of this, how to represent program data in a format than many computers can understand. However it is seems much easier than bypassing the hardware issues of baudrates and frequencies.