Commander X16

I have the feeling that CX16 is way too fast for  a real 1541. Maybe if we specify a more performant standard on that DIN connector it could be used for more "new retro" periPherals.

a faster port  could greatly compensate for an absence of user port too.

 

A faster IEC protocol already exists -- burst mode or flash mode on a 1571 can go substantially faster than a 1541.

Heck, even a 1541 can go 6× faster than the standard C64 kernal routines, just by using a fastloader, so I think it's actually plenty fast enough.

Yes : my question was: should we keep the standard routine or should we use an improved one?

is it possible to link the SRQ line to the via?

anyway I Don't think that the CX16 should consider the 1541 it's ideal disk drive because, you know, it doesn't make much sense to have more ram than disk space.

a sort of 1581 is much more "time correct"

Well, no. Its ideal disk drive is the SD card. ? The IEC stuff is mostly about backward compatibility and being able to 'rescue' the data that's 'trapped' on those old floppies.

Fabio, you're right though, and we have mused about how to best implement IEC on the X16.  Since this is not a C64 clone, we're not bound by the ridiculousness of the 1541 disk drive, but rather the general IEC protocol... so we should consider burst mode and so on.

That said, it's easy for me to say what "should be done," since I am not an assembly language programmer...

 

On 10/18/2022 at 11:50 AM, rje said:

That said, it's easy for me to say what "should be done," since I am not an assembly language programmer...

If you knew assembly would it make it harder to voice an opinion of what should be done? Or does your C background disqualify you? ?

Opinion is ... well you know how forums work.

If I knew the 6502 well, I'd probably try it.  I'm interested enough to want to do it, but too lazy to make all the inevitable learning-mistakes as I go.  So when I voice an opinion it's ignorant of the technical solution.  There's hardware needed to do this well.  This all amounts to a large tech debt for me.  But my opinion isn't business-based either.  So, yeah, my opinion is not really worth much.

We've all watched Michael Steil's video on speeding up the 1541, right?  I watch that and I say that's what we need.  But frankly the IEC port will mainly be used with something like SD2IEC or perhaps, if we're lucky, the Raspberry Pi IEC Mass Storage Device thingy that doesn't yet exist.  So it has to play with them, and that's probably all it has to do.

 

They are going to bit bang the IEC port, and there have been assurances that it is wired to be be able to operate in burst mode. Even if support code to do that has to be loaded, having to load support code is less of an issue with the X16 than the C64, since the X16 will load an autoexec.x16 basic file if present, and that file can load the support code.

Now, if it is bit banged it will not have the same speedup as it would have with hardware support ... but, simply running at 8MHz will allow it to be a bit faster ... but OTOH, if they bring out the unused handshake lines from VIA#1, it might be possible to wire up a hardware assisted burst mode and get a reasonably high speed IEC interface. After all, the burst mode for the C64 adapter basically uses CIA lines on the C64 User Port for the same purpose.

I seriously hope the X16 take advantage of VIA burst mode with code in ROM. It was after all intended to be present on the original C64 but a chip defect and PCB manufacturer screwed it up.