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Help needed: identifying which computer was this program written for

P

pkmpad

New Member
Joined
Jan 24, 2021
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5
Hello everyone.

I found an old tape with two homemade programs written on it, one on each side. I would be highly interested in backing up these programs as ROM files. However, I do not know what computer they were programed for. :(

These are the links to the .wav files:

https://ftp.ea4rct.org/radioclub/upload/archivo_historico/cassettes/Programas/WAV/factorial.wav

https://ftp.ea4rct.org/radioclub/upload/archivo_historico/cassettes/Programas/WAV/polarCart.wav

Sadly, I have no enought experience for finding this information, and there does not seem to be any straightforward solution to this issue but finding someone that recognises the sound of the preamble/program. I post this here with the hope of finding someone that can tell either which computer these recordings correspond to or, at list, start ruling out candidates. :eek:

Thank you very much in advance! :D
 
Honestly, you should convert these in to binary and start throwing disassemblers at them. You should try a 6502 disassembler and a Z80 disassembler.

Both of those will be pretty enlightening pretty quick.

Even if you don't have great familiarity with assembly language, odds are high that one disassembly will look like utter nonsense, and the other one more signal, than noise.

Once you've done that, I bet if you pasted a page of the disassembly, notably anything that looks like it makes calls "outside" of the program (for 6502 that would likely be JSRs to higher addresses, on the Z80/8080 it's probably interrupts). Also, on the 6502 any Zero Page addresses will tell tale it quite quickly.

And, of course, I say 6502 and Z80 because that's 90+% of what anything was written for in the day. The odds of it being a 6800 or TMS9900 or anything else is REALLY low.

So, give is a couple of stabs with some disassemblers and post your results.
 
Wouldn't you need to know for which computer these are for in order to convert them to binary? But if he knew that, this thread wouldn't exist.
 
Timo W. said:
Wouldn't you need to know for which computer these are for in order to convert them to binary? But if he knew that, this thread wouldn't exist.
Click to expand...

Not necessarily. It should be possible to figure out the frequency of the leader and the frequency of the signal shifts and whether or not stop bits are used from the wave form. That would narrow the list of possible systems to just a few.

I suspect it would be faster to write a new version of these programs than to extract from the cassettes. A factorial program was a sample for the Sol 20 and Wang 2200. Presumably, the other would be for converting Polar Cartesian coordinates which I think was an assignment in Intro to Programming 40+ years ago.
 
Thank you very much for the info!

Efectively, this tape corresponds to some homework of an engineering student almost 40 years ago! :eek:

I can try converting them to binary. Is there any recommended software for this purpose?

Thanks!
 
Thank you for your response!

Would you recommend any software for any of both (conversion to binary/disassembly) purposes?
 
g4ugm said:
I think you are out of bandwidth! I would try feeding it into MMTTY. This will show you the mark/space frequencies and decode it if its 300 baud or less...
Click to expand...

Dear Dave G4UGM. What do you mean by out of bandwidth? Does this only refer to MMTTY?
 
Maybe reload them after placing in Zip files. That should reduce the size by 90%. I saw it was 50 MB WAV yesterday and didn't download.
 
krebizfan said:
Maybe reload them after placing in Zip files. That should reduce the size by 90%. I saw it was 50 MB WAV yesterday and didn't download.
Click to expand...

So sorry for the inconvenience, we are having some trouble with our ftp server these days. I will post whenever they are solved.

By the way, user nc513 has been able to decode polarCart.wav. It was a program for the C64!

However, with respect to factorial.wav, I am having much more trouble. Analysing the .wav file with audacity, it does not seem to have any FSK modulation on it. Here are some crops of the signal matching the moments when the typical tape-loading sound occurs:

3.png

2.png

1.png

Thank you in advance!
 
Aloha !

pkmpad said:
However, with respect to factorial.wav, I am having much more trouble. Analysing the .wav file with audacity.
Click to expand...
Even more: When I simply listen to the WAV it sounds terrible. It clearly is a data signal, possibly another C64 program, but there is a nasty hum in the background, a huge wow/flutter-like distortion, and the amplitude is not consistent.


I did put the 'polarCart' in a D64 disk image and ran it. Not to be disrespectful but the program(ming) is really bad. If this is a precurser to what could be in 'factorial' then in my humble opinion it is not even worth the effort...
However, if you do wish to at least run 'factorial' (I know I would if only for nostalgic reasons) I think we are going to need a new WAV file to sink our teeth in.




Cheeeeeeeeers and stay safe !


Jecepede


PS: I did not post the D64 image due to the fact the little program contains a name, an address and a phone number.
 
g4ugm said:
Probably need to decode to binary....
Click to expand...
Hi Dave, Came across one of your postings about your work on a TR-10 analog. Are you anywhere near the Philadelphia area? I have a bunch of EAI analogs and could use massive amounts of advice on the simple things...like how to start cleaning them!! Hope to hear from you. You can get me at director@TheComputerChurch.org.
Have a great day,
Michael
 
Hi Michael,

As this appears to be your first post on VCFED (despite joining in 2018) - welcome!

Anyone called Dave is based in the UK I am afraid!

It is interesting that you have a bunch of EAI analogue computers though. I hope you would like to get them working!

Please create a separate thread and let’s see what can be done!

You appear to have a very nice building and collection: http://www.thecomputerchurch.org/.

Dave
 
The first thing I'd do is look at the signal on a digital scope. I'd sample the header and the data. It will tell you a lot more about how it was recorded than just guessing.
It might be a fully digital recording, with both digital data and clocking combined. The fact that it seems to have woow makes one think it was recorded on a really cheap deck with no capstan.
Dwight
 
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