I am working with my Model 30, 8530-021. I wanted to do some direct interrogation to the hard disk registers, but when I attempt io read/writes to 320h - 32fh (using debug, or basic , etc) they do not actually get to the drive no activity on cs1fx,iow,ior etc, but when I run fdisk etc there is activity.

Is there a secret way to access directly/unask/ and not through dos int?

I see from the planar schematic that Pin23 (CS1FX) on J11 is controlled by Pin62 on U9 / 72X8203, which seems is the factory programed gate array so that is a dead end for me.

I guess this is a case of inspecting the bios if it is not already common knowledge. It would seem the misuse of this connector and the unlisted A3 line I was dreaming about may not be possible.

On Thursday, 13 July 2023 at 20:29:57 UTC-4, Kevin Moonlight wrote:
> I am working with my Model 30, 8530-021. I wanted to do some direct interrogation to the hard disk registers, but when I attempt io read/writes to 320h - 32fh (using debug, or basic , etc) they do not actually get to the drive no activity on cs1fx,iow,ior etc, but when I run fdisk etc there is activity.
>
> Is there a secret way to access directly/unask/ and not through dos int?

Okay, my first attempt at inspecting disassembled bios code moved me a step forward, may still all be pointless though. not sure how this applies to the 286 planar, but more important is A3 connected to Pin31 on J11 in a model 30 286? it is not on the schematic so that is not promising. I have not acquired a 286 model 30 yet, still working on that.

It seems bit0 of port 65h controls if 320-32f is masked or not, when set to 1 the io read/writes to 0x32X appear at J11 as expected with cs1fx being properly asserted..

I do not see port 65h mentioned in my undocumented PC book, other general references refer to it as part of the keyboard controller.

Now I can move onto phase2 of my ps/2 crime spree.

On Friday, 14 July 2023 at 00:24:59 UTC-4, Kevin Moonlight wrote:
> I see from the planar schematic that Pin23 (CS1FX) on J11 is controlled by Pin62 on U9 / 72X8203, which seems is the factory programed gate array so that is a dead end for me.
>
> I guess this is a case of inspecting the bios if it is not already common knowledge. It would seem the misuse of this connector and the unlisted A3 line I was dreaming about may not be possible.
> On Thursday, 13 July 2023 at 20:29:57 UTC-4, Kevin Moonlight wrote:
> > I am working with my Model 30, 8530-021. I wanted to do some direct interrogation to the hard disk registers, but when I attempt io read/writes to 320h - 32fh (using debug, or basic , etc) they do not actually get to the drive no activity on cs1fx,iow,ior etc, but when I run fdisk etc there is activity.
> >
> > Is there a secret way to access directly/unask/ and not through dos int?

Drive it like you stole it...

You don't know what it's like... [U and me for J.P.]

Kevin Moonlight wrote:
> Now I can move onto phase2 of my ps/2 crime spree

> It seems bit0 of port 65h controls if 320-32f is masked or not, when set to 1 the io
> read/writes to 0x32X appear at J11 as expected with cs1fx being properly asserted..
>
> I do not see port 65h mentioned in my undocumented PC book, other general
> references refer to it as part of the keyboard controller.

Bit 0 of I/O port 65h is presence detect that a hard drive is connected. 65h is an attached/enabled status register unique to the 8086-based Model 25 and 30 (and Model 30 clone Epson Equity 1e). I've only seen it officially listed in the Model 30 Technical Reference: https://youtu.be/JmrKx7wHGLI

> Bit 0 of I/O port 65h is presence detect that a hard drive is connected. 65h is an attached/enabled status register unique to the 8086-based Model 25 and 30 (and Model 30 clone Epson Equity 1e). I've only seen it officially listed in the Model 30 Technical Reference: https://youtu.be/JmrKx7wHGLI

I watched your video on the planar control register 2 years ago according to youtube but did not absorb it as I did not have a Model 30 at that time. I suppose I did not search hard enough, although searching the internet for a 2 digit number is not easy. It would seem 65h resides inside U9. It would look like bios only sets this after successfully identifying an attached drive, when a dead drive is in it resulting in fixed disk error, this bit is left as 0.

As I showed, by setting bit0 to 1 I was able to make use of the CH375 usb storage chip off the J11 HD port, which may be interesting in itself to users that are not using the HDD and instead have a scsi card installed, this would let you get the USB without eatting another ISA slot. My goal however is to use HDD & USB at the same time, which seems to be possible on the 8086 Model 30 because of A3 being wired into Pin 31. Pin 31 is listed as reserved on the ardent-tool HD pinout page, on the planar schematic you can see it is connected to A3 and confirmed with multimeter.

I do not have a 286 Model 30 on hand yet, the schematic does not show the A3 being connected, so I suspect it is not which limits the opportunity to abuse this port for simultaneous use of an HDD and storage. Still potentially useful in situations where user does not care to use an HDD (or emulated HDD) but would like to get removable usb storage without killing an isa slot.