Posted By
someone
on 2002-10-11
|  controlling the 1551
Does anyone know something about the communication between the computer and the 1551?
I'm looking for a description of the control protocol the +4/C16 uses to access the 1551.
A source of a 1551 speed loader (maybe with little comments) would be nice.
Alternatively, a verbal description like this could help:
write data byte to port X
set bit A of port Y
wait for bit B set on port Z
clear bit A of port Y
write next data byte
...
I think there has to be some logical channels opened (like the ones the 1541 uses)?
The goal is to build an interface that connects the 1551 to an ordinary RS232 serial port nearly every computer has.
The control protocol of the serial side will be something like XMODEM, so every terminal program could be used to "upload/download"
software (like the nice games on this site) between the computer and the 1551.
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Posted By
SVS
on 2002-10-12
 | You can manage the connection in the same way
as you do it with a 1541. O.S. cares about the TCBM encoding.
Then:
a) SETLFN Set logical device
b) SETNAM set file name
c) OPEN filed
d) Read, Save...
e) CLOSE
If you need further deep info (like TALK/UNTALK subroutines), reply here, OK?
Have a good working 
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Posted By
someone
on 2002-10-12
| (no topic)
OK, via the OS I think it's not the problem.
But I have to do it at the lowest level (direct access to the TIA 6523), in a way I have to implement the TCBM protocol on a different hardware (I plan to use a 8051 microcontroller).
I had one or two looks at the ROM routines already, but somewhere I've lost track...
It would be very nice if you could explain me the required subroutines in depth.
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Posted By
SVS
on 2002-10-14
| I cannot help you to direct drive the 6523, but
I could write you the procedure to send low-level commands to an external device, as I wrote (TALK, UNTALK, etc.). This could take me time, because I have to search inside old documents, then reply me if you are interesting in it.
BTW what's in detail your project?
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Posted By
someone
on 2002-10-14
| > BTW what's in detail your project?
Well, as I stated above the final destination is to develop an adapter which directly connects to the 1551 at one side and to a serial interface (RS232) at the other.
The adapter's software will provide a minimal set of disk access functions for the 1551 (display a directory, read and write sequential files) and control the serial transmission via XMODEM protocol (or something similar). This allows me to use almost any computer having a serial port with any kind of terminal software to transfer files from or to 1551 diskettes (e.g. to store games downloaded form the net).The adapter will be mainly consisting of an 8051 microcontroller and this is the reason why I need the description of the low level access to the 1551's 6523, because I have to implement the control protocol using completely different hardware and assembly language compared to the commodore 7501/8501 processor.
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Posted By
SVS
on 2002-10-14
| I understand. In this case I can not to help you very much,
but for the low-level command-codes TO THE DISK-DRIVE O.S.
The HW connections are out of my knowledge, sorry.
Keep me informed.
Bye
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Posted By
JamesC
on 2002-10-14
| Sound to me like
someone is trying to build an X-1551 cable, like the X-1541 series but for the 1551.
Might be a lot easier to buy an X-1541 cable and a 1541, as the software already exists and both hardware and software are proven. This would save a lot of headaches with software bugs and loose wires or miswired connections.
Over here in the States, the X-1541 cables are around $20, plus another $10-20 for a used 1541. I'm sure that European pricing in Euros is similar, from what I've seen on various Ebay sites.
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Posted By
someone
on 2002-10-15
| Just imagine for a few seconds
that not everyone owns a PC...
To buy an X-1541 cable and a 1541 drive isn't that problem, but how to connect this to real computers with real processors???
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Posted By
JamesC
on 2002-10-15
| ...
Well, what are you going to connect it to?
I assembled my own PCs from the ground up. I built my wife's, my father's, my mother-in-law's, my daughter's, and my own. These are not toys, these are real computers with real processors in them.
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Posted By
MagerValp
on 2002-10-15
| (no topic)
Sounds like he's talking about actually building a computer, not just assembling motherboard, cpu, and cards. You know: soldering iron, chips, and a lot of free time
The 1551 protocol is interesting since it's reasonably fast yet not very timing sensitive. In fact an X1551 interface for PCs would work a lot better than the X1541 interface does, especially under Windows. It'd be faster too...
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Posted By
someone
on 2002-10-15
| OK, maybe I missed to set visible >irony< tags...
In my opinion the whole family of 80x86 processors is not the top of hardware design (remember the ridiculous segmented addressing and the poor register set). Therefore I decided one day never to buy such a machine. A >real processor< has a linear address space and a bunch of universal registers (examples? Motorola 680X0 with 8+8 regs, PowerPC with 32, Itanium...).
What I wanted to say is that you can't use the X-1541 cable with machines other than PC. Actually I have a Mac and this machine doesn't even has a parallel port where the cable could be plugged in (apart from the fact that the cable driver software doesn't run on a Mac...).
The main advantage of the 1551 adapter I'm going to build is that I don't need special software on the computer, only a terminal program. The adapter's firmware will provide the user interface - I'm thinking about a simple surface resembling a plain old BBS files section (upload, download, directory).
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Posted By
MagerValp
on 2002-10-17
| Serial Slave
You might want to take a peek at my Serial Slave, http://www.cling.gu.se/~cl3polof/serslave/
It allows you to copy files and disks over an RS-232 interface. If you're running MacOS X it shouldn't be too hard to get it up and running, it already runs on Windows and Linux.
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Posted By
someone
on 2002-10-18
| Thank you for this tip,
but since I only own a C116, I can't use the software without expansion of my hardware too, although I think the C64 driver could be adapted to run on a Plus 4. Unfortunately the C116 doesn't have an RS232 interface on board.
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Posted By
MagerValp
on 2002-10-18
| C16/116
Ah, yes, it requires a Plus/4 to work.
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