[Coco] Glenside IDE + Multi-Pak + HDB-DOS

[Barry Nelson]

If you are using a Y-cable and not a Multipak, the Floppy controller mirrors its addresses from FF40-FF4F to FF50-FF5F so you would want to use FF70-FF7F for the Glenside IDE controller. I don't think I would want one of these contraptions connected to my CoCo without adding some additional address decode patches to eliminate some of the conflicts. Since the Glenside IDE only needs FF70-FF77 or FF50-FF57, I would first add circuit to disable the cards I/O for addresses FFx8-FFxF. Since the card as currently designed additionally does not fully honor the Multipak select lines, I would either fix it so it did and update the drivers as appropriate, or at a minimum definitely support at least the two address options. Otherwise that ugly hack is not getting ANYWHERE NEAR my CoCo 3!

PS: The floppy controller I use on my CoCo 3 is hardware patched to eliminate the FF50-FF5F address selection, so it only responds to FF40-FF4F. This has caused zero compatibility issues in 20+ years of use. I did this using a couple of diodes and a resistor.

> Mark J. Blair nf6x at nf6x.net 
> Sun Sep 11 15:58:51 EDT 2016
> I apologize if I seem pedantic, but we seem to be talking at right angles, Bill. I know how to jumper the Glenside IDE hardware. My question is specifically about Boisy's comment in the HDB-DOS source code from Toolshed which states:
> 
> "note that the Glenside IDE controller does NOT work with an MPI using this current version of HDB-DOS"
> 
> My question is:
> 
> Is the addressing conflict at $FF7F the *ONLY* reason behind that comment in the HDB-DOS source code?
> 
> I suppose I can also ask a related question: Why would a user without an MPI "probably want to use the 16-bit $FF7x driver"? Wouldn't the $FF5x configuration work in all cases?
> 
> My motivation for asking these pedantic questions is that I'm designing a compact Glenside-IDE-compatible CF card adapter with ROM to fit in the lovely SuperPak cases, and I want to fully understand any compatibility issues so I can maximize its utility to anybody who might be interested in it. I'm left wondering whether there's a real need for it to support the $FF7x base address at all. Eliminating an unnecessary configuration switch would very slightly decrease cost and complexity.