XT-IDE on PCjr

[Hargle]

#5 - I think this is a throwback to the original IDE controller design that andrew brought in from his own projects. I did find a note in the ATA-2 spec that says:
"Note 1: This register is obsolete. It is recommended that a device not respond
to a read of this address. If a device does respond, it shall be sure not to
drive the DD7 signal to prevent possible conflict with floppy disk
implementations."

Happy to help with #9. Mike has the latest code, but it was originally mine so we can certainly get you going with that easily enough.

I'm just about to have XTIDE rev 2 parts show up, so I'm going to going through your exact same situation on the non-jr front, so I can share your pain.

[Brutman]

I'm using MASM 6.11 to build. It runs in an XP DOS window. At worst case you will need to install Virtual Box or VMWare and do it in a virtual machine if XP is too old for you. I can help you get setup.

My version is based on 0.9, which came from Hargle. I'm simplified it quite a bit for features we'll never have, like multiple card support. It still has some kludges in it - I need to fix those and then have Hargle review it before sending it out.

The most interesting kludge that I'm kind of proud of is using the BASIC cartridge as a chicken switch. If the cartridge is present the BIOS will not initialize. This gives me a way to test without having an EPROM burner. (Yes, I still haven't bought one.) At some point I have to remove that kludge and pick some better addresses in reserved areas to use. Some of that doesn't need to be done with your card though - you have far more options that I do with a first revision XT-IDE card.

[jmetal88]

Hi guys! I was just thinking, I might want to take up my branch of the project again, but take it in a different direction.

I'm thinking about, now, designing some kind of a 'budget' model IDE board. Right now, I'm thinking about something designed specifically to use a flash disk, that can fit in the modem slot, and perhaps get some of the missing signals it needs from the CPU socket. It would also have only the IDE facilities, and nothing else.

I'll let you guys know what kind of progress I'm making later on, if any.

EDIT: Eh, I'm thinking this isn't that great an idea, now. I'd still like to do a 'budget' board, but sticking it inside the PCjr would probably be more trouble than it's worth. Also, I've kind of just lost enthusiasm for designing the thing at the moment. Alan's board still seems like a great solution to put inside an old memory sidecar, though!

[Hargle]

for what it's worth, I'm still very optimistic and enthusiastic about this particular project and still want to see it move forward. Especially since I will likely be picking up a THIRD pcjr system in a couple weeks. (why??!)

Real life has taken a lot of my time lately, but I'll most certainly be back in the swing of things in a month or two. I'm slowly debugging XTIDE rev2 right now, and when that is complete I want to jump onto jrIDE in a big way, and will want some hardware to play with when that happens!

So, don't give up. Let's get all of our back to school stuff done and then refocus on this in the fall.

[Brutman]

JMetal88 ..

The modem slot is kind of a non-starter - there just are too few address lines going to it. Jumpering extra wires to make up for it is kind of a messy kludge too. I think the modem slot would be better suited to another 8250 UART or even a 16550 UART, but the latter would require a slightly different BIOS. (Or skipping the BIOS routines for programming it entirely and just coding to the registers.)

I'm still getting good use out of my XT-IDE on the Jr, even if it is exposed and ugly. I'd really like to get back to a simpler design - 512KB SRAM and the XT-IDE (first version, with the minor performance tweaks) is all we really need. If it fits in a sidecar it makes a nice package - Alan demonstrated that. I'd be happy running a ribbon cable out the back or using a standard sized 40 pin Disk on Module connected directly to the cable header.


Mike

[jmetal88]

JMetal88 ..

The modem slot is kind of a non-starter - there just are too few address lines going to it. Jumpering extra wires to make up for it is kind of a messy kludge too. I think the modem slot would be better suited to another 8250 UART or even a 16550 UART, but the latter would require a slightly different BIOS. (Or skipping the BIOS routines for programming it entirely and just coding to the registers.)

I'm still getting good use out of my XT-IDE on the Jr, even if it is exposed and ugly. I'd really like to get back to a simpler design - 512KB SRAM and the XT-IDE (first version, with the minor performance tweaks) is all we really need. If it fits in a sidecar it makes a nice package - Alan demonstrated that. I'd be happy running a ribbon cable out the back or using a standard sized 40 pin Disk on Module connected directly to the cable header.


Mike

OK Mike, how about this:

Alan can take care of a feature-full high-performance IDE board. I will simply adapt the original XT-IDE design to make it more convenient to attach to the PCjr. It will use the same BIOS that you already modified.

Sound good? I could also put 512k of RAM on the board.

The main idea is to make something easy to produce, based on a design that's already proven. You'll still have to steal some memory for the drive tables, but I think I can live with that. If you've found anything to indicate any serious issues with that, let me know.

[Brutman]

Before we make any decisions ..

Alan - are you working on the 2nd spin of your design?

[alanh]

Ok, I think I'm finally getting back to this. Sorry for the delays. I'm all moved into the new place and settled. I tentatively have a few hours each night this week to give it ago. I'm pulling down the source tonight and trying to get a MASM setup working to at least be able to rebuild. Along with getting my 386 hooked up with PC/NFS and good old floppy-net to the Jr to try out code. I'll see how it goes.

Is the googlecode - nasm compilable source the source code I should be looking at?

Edit: Already discovered I'm going to have to make a special trip back to the old house tomorrow to pull another 5.25" DD from an old machine. Brought 3 to the apartment and only 1 works.

[alanh]

My time sheet this week had 65 hours. However I'm currently doing some basic prove outs of the board. Where can I get a later version of DOS (than 2.1 which I'm running)? Preferably a patched version of 5.0 or 6.x? Of course the vanilla 6.22 hangs. I did write an extensive memory test which included aggresive aliasing checks and that all passed. I'm going to move on to dynamic memory map, RTC and flash testing tomorrow.

[Brutman]

My time sheet this week had 65 hours. However I'm currently doing some basic prove outs of the board. Where can I get a later version of DOS (than 2.1 which I'm running)? Preferably a patched version of 5.0 or 6.x? Of course the vanilla 6.22 hangs. I did write an extensive memory test which included aggresive aliasing checks and that all passed. I'm going to move on to dynamic memory map, RTC and flash testing tomorrow.

Alan,

I'll have a patched IBM PC DOS 5 for you tomorrow night. Just write the image and boot ..

I've been painting the house. Spend 14 hrs this weekend on ladders, on the roof, etc ...


Mike