[Coco] Transferring software from PC to Coco2 with RS-232 pak?

John W. Linville linville at tuxdriver.com
Mon Mar 21 16:41:29 EDT 2016

On Sun, Mar 20, 2016 at 07:09:08PM +0000, Brian Taylor wrote:
> I recently obtained a Coco 2 with a whole boatload of perhiperals 
> including two disk drives, Multipak, RS-232 program pak and cassette 
> recorder.
> I tried transferring .CAS files to tape with CASOUT and CocoTape but 
> they only seem to work half the time, and always fail to load (IO error) 
> any games bigger than 10KB.

Volume adjustment can be tricky, but it is usually achievable with
those sorts of programs...

> I have the RS-232 pak hooked up to an old ThinkPad with HyperTerminal, 
> and have succeeded in transferring text files to the Coco, with these 
> settings:
> 9600 baud
> Half duplex
> 8 bit word length
> No parity
> 1 stop bit
> But I want to transfer programs. I tried transferring a machine language 
> game .CAS file, using "Receive Machine Code" on the Coco, and the 
> correct starting address, but I get a "* DATA ERROR *" on the Coco no 
> matter what protocol I use (Kermit, X/Y/Zmodem). Lowering the baud rate 
> doesn't fix it, either.

Well, the main thing is the CAS file is not what you want to
transfer (more below). You also should _not_ be using any file
transfer protocol per se. Instead you need to do a "plain ASCII",
"plain text" or similarly named transfer. Compuserve used to call it
"DC-2/DC-4", apparently...

Also, IIRC you have to send a 1-byte "checksum" at the end.  Basically
it is a single-byte running sum of every byte transferred, with the
overflow truncated after each byte is added. Or, something like that...

> Are .CAS files just not transferrable this way? Is there any way to 
> convert a game in .CAS or .DSK format to a .BIN file that I could 
> transfer? Or should I try another terminal program instead of the one 
> loaded on the RS-232 pak?

You want none of the above types of files. What is needed is the
raw binary image of the game. You would have to extract the BIN from
the CAS or DSK file, strip the BIN header and footer, and transfer
the remaining data. If it is a multi-part BIN then it is even more
complicated but essentially the same -- not for the faint of heart!

Machine language transfers with the Deluxe RS-232 Pak are doable,
but are better done when writing your own code (including your own
checksum computation tool)!

John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.

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