XT-IDE on PCjr

Hardware questions and modifications

Re: XT-IDE on PCjr

Postby Brutman » Tue Apr 12, 2011 11:15 am

The general idea is that we figure out what we want (as a group) and narrow it down to things that we think are doable. So while the IDE adapter and extra memory are fairly straightforward to do, the other features are things that not everybody might want and might introduce uncertainty/risk into the project.

Then comes the fun part - design and debug. Matt and I have done a little bit of this. We have other resources to turn to for help and guidance. But there is a fair bit of effort involved.

The last stage is getting custom circuit boards run off. That is where the group buy comes in - you can imagine that fabricating a circuit board is expensive. So the more units we order, the more the cost gets spread. The same goes for buying the components that go on the board.

So regardless of skill level, chip in with what you'd like to see and how it should like. A sidecar would be wonderful but I think at the moment we can't get a match on the connectors, and we'd have to cannibalize other sidecars to do it. I'm not too thrilled about that. A separate small expansion chassis connected by a cable is possible, but that would require more room on your desk, a nasty cable hanging outside of the box, and another power supply. Finding a nice enclosure might be a challenge too - the one referenced earlier (Huntec) doesn't have fan, but it has other nice features.

Wacked out ideas are welcome too. By definition we are already in uncharted territory. ;-0
Brutman
Site Admin
 
Posts: 951
Joined: Sat Jun 21, 2008 5:03 pm

Re: XT-IDE on PCjr

Postby MattCarp » Tue Apr 12, 2011 7:18 pm

With that, there are a few major questions to answer:

1. Who is doing the board?
2. What is the suitable enclosure?
3. What will we put on it?

The answer to #1 will greatly influenced how #2 and #3 are answered. Myself, I'm reluctant to take on the board at the moment - I have one other project and am stuck on a Mac where good / cheap / free tools are scarce. I have Eagle, but find it a bit hard to use (!).

Regarding #2, I think any working enclosure would be great. My preference is an enclosure that seamlessly fits with the jr mechanicals, which leads me to either a sidecar or a Racore unit. I can understand not chewing up a bunch of sidecars, but they're out there, perhaps $10-20. That's about the same as what the specialized sidecar connectors would cost anyway, and you get the plastic casing, too. I think we all may even have a nonfunctional one to use. To me, the downside on the sidecar is just the limited real estate. I'd love to be able to get everything from my list in my last post on to the card, including a 2.5" PATA hard disk! How cool would that be?

Regarding #3, I'd be interested in comments on the list and priorities I suggested. I know ethernet is a risky wildcard. Maybe we need someone (myself?) to toy around with it as a solo project. If it can be proven, then if there's room, it could be grafted onto the project, perhaps at a later date. The challenge with the ethernet controller is that, even if hardware isn't hard, there's a packet driver that needs written and that's out of my area of expertise. It doesn't intimidate me, rather, I think it would be a steep climb for me. I hear there's a pretty good developer doing some PCjr network programming though. Maybe someone can track him down....

:)
MattCarp
 
Posts: 60
Joined: Sun Aug 31, 2008 11:35 am

Re: XT-IDE on PCjr

Postby jmetal88 » Tue Apr 12, 2011 9:15 pm

Well, if you guys want a sidecar, here's a rendering of a board I came up with using KiCAD and Freerouting.net that has IDE and memory. I haven't thoroughly checked it for errors yet, and I'm not sure the dimensions are completely accurate, but this at least gives you an idea as to what I'm trying to do.
Attachments
JR-IDE.PNG
PCjr IDE and Memory Sidecar Rendering
(78.59 KiB) Not downloaded yet
jmetal88
 
Posts: 794
Joined: Sun Jul 25, 2010 10:22 am

Re: XT-IDE on PCjr

Postby southernbob » Wed Apr 13, 2011 11:56 am

The connector that can't be found has 2 female 'holes' and just pops off once the small bolts
are removed, at least that is the way on the printer sidecar. This plugs into the other 'pins' connector
that a source of them has been found.This means that a new sidecar could be made by using
the 'pins' connector and soldering it to the new board and then plug the female connector
from the printer sidecar into that. Or, if the new sidecar is to be the last sidecar and doesn't
have to propagate the signal to another sidecar, just solder some pins to the new card
and possibly a 'double decker' sidecar could be made. Of course there is always the
problem of having enough power to power everything on Matt's 'big' list of things wanted.
And then there is the cooling thing......

This doesn't destroy a working printer sidecar so if the new card doesn't work out, the
connector can be put back on the printer sidecar.
That is my 2 cents, hope it makes some sense.
Bob
southernbob
 
Posts: 36
Joined: Mon Jun 23, 2008 10:36 am

Re: XT-IDE on PCjr

Postby MattCarp » Thu Apr 14, 2011 6:05 am

jmetal88 wrote:Well, if you guys want a sidecar, here's a rendering of a board I came up with using KiCAD and Freerouting.net that has IDE and memory. I haven't thoroughly checked it for errors yet, and I'm not sure the dimensions are completely accurate, but this at least gives you an idea as to what I'm trying to do.


Dude! (a term I reserve and only say with great affection!) You've done the hard work!

Ok, how about squeezing in the ethernet controller? It just might be possible - it's just the chip, a small config EEPROM (93C46), a crystal, 5 resistors, 2 capacitors, the isolation transformer, and the RJ45 jack (with the integrated link/active LEDs)! We don't need an address decoder or boot-PROM and buffer. The controller chip is a 100-pin TQFP, which ain't small, but the EEPROM is small (6 pin SOT-23, 3 mm wide!) and the passive components are tiny!

http://www.cirrus.com/en/pubs/proDatash ... 00A_F5.pdf See page 11.
Last edited by MattCarp on Thu Apr 14, 2011 6:54 am, edited 1 time in total.
MattCarp
 
Posts: 60
Joined: Sun Aug 31, 2008 11:35 am

Re: XT-IDE on PCjr

Postby Vorticon » Thu Apr 14, 2011 6:09 am

All else considered, I would much prefer a sidecar solution if at all possible. Again, a bootable IDE drive should be the main priority. Trying to create a do-it-all device will likely add complexity as well as cost to the project. While an ethernet adapter would be great, there are perfectly functional parallel adapters out there on Ebay, and so this would not constitute a high priority item. Add to that the need for a driver and the complexities multiply.
Just my 2 cents. Regardless of the direction this project takes however, please count me in for a board :)
Vorticon
 
Posts: 276
Joined: Fri Nov 27, 2009 7:25 am

Re: XT-IDE on PCjr

Postby MattCarp » Thu Apr 14, 2011 7:11 am

just two more thoughts -

if there were room for the ethernet controller, how about just designing it on the board, and leaving it to the individual if they want to populate the parts? with only 12 parts, it would be easy to put the parts on if you'd like.

The current draw on the ethernet controller is only 60 mA. I seem to recall 400 mA power budget for the PCjr's I/O port, which should leave enough juice for the memory and IDE controller.

Actually putting a laptop hard disk in the sidecar is probably not be feasible. While the 2.5" form factor may squeeze in there, a quick check of western digital web sites reveals that the power required by their smallest PATA laptop drives is on the order of 500mA. An older IBM Travelstar seems to take 1A... Maybe an IDE-connected compact flash chip? I guess I'm just determined!
MattCarp
 
Posts: 60
Joined: Sun Aug 31, 2008 11:35 am

Re: XT-IDE on PCjr

Postby Brutman » Thu Apr 14, 2011 11:23 am

If I'm not commenting at length, excuse me - I'm distracted. (Announced my resignation from IBM yesterday.)

Take a look at "Disk on Module" - it looks and smells like an IDE hard drive, but it is FLASH based. You don't have the hassle of CF to IDE adapters and finding a compatible DF card.

No moving parts, no heat, and low power consumption. I've tested one with the XT-IDE on a Jr already.
Brutman
Site Admin
 
Posts: 951
Joined: Sat Jun 21, 2008 5:03 pm

Re: XT-IDE on PCjr

Postby jmetal88 » Thu Apr 14, 2011 11:41 am

This one would be easy to fit in a sidecar:

http://www.howardcomputers.com/accessor ... d=S5239971

And at 128mb, it's the perfect size for four 32mb partitions on DOS 3.3. :)

I think I'll try revising my PCB design for the 44-pin connector, so the module could be plugged in directly.
jmetal88
 
Posts: 794
Joined: Sun Jul 25, 2010 10:22 am

Re: XT-IDE on PCjr

Postby Brutman » Thu Apr 14, 2011 12:01 pm

Stick with the 40 pin IDE connector instead of the 44 pin laptop IDE connector - that gives people the option of running a cable to an IDE drive, using a 40 pin Disk On Module, or using a 44 pin laptop drive (FLASH or otherwise) with an adapter.

If you go with the 44 pin we are locked into that - there are few/no adapters that can put a 40 pin drive on the 44 pin connector. (And yes they can be made, but it's irritating.)
Brutman
Site Admin
 
Posts: 951
Joined: Sat Jun 21, 2008 5:03 pm

PreviousNext

Return to PCjr Hardware

Who is online

Users browsing this forum: No registered users and 2 guests

cron