Having XT Fun!

[Al Hartman]

Nope. Got it handled.

No cables were harmed in the creation of this message.

 

[Al Hartman]

The correct floppy cable arrived today, and has been installed. XT now boots to MS-DOS 3.3.

My motherboard has the empty socket for the multiplexer chip, and I see where the E2 jumper is. 640k, here I come!

I wonder if the pulled 64k chips will work in a Coco 2?

 

[Al Hartman]

Ok...

1. Floppy drives are working great with the cable I got from eBay. Connectors I ordered still aren't here because they keep shipping me the wrong ones.

2. Logic board upgraded to 640k.

3. EV-170a Multi I/O board installed and working. Clock has new battery and responds to timer.com.

4. Backpack 3.5" drive is installed and working.

All that's left is to build and test the Lo-Tech XT IDE board. I just need two sockets, and I can finish it up. Hopefully in the next day or two. I'm building two boards, so I have a good chance of having one work first time.

Then, I'll test various hard drives I have to see which will work. I'm thinking of using MS-DOS 5.0 when I install the mass storage. Or, would DOS 3.3 be better?

 

[Caluser2000]

If you want to put up with 32meg partition sizes use MS/PC Dos 3.3. If not use something else. Compaq had an OEM ver called 3.31 which got over that barrier.

 

[fatwizard]

I believe that ver. 3.3 will be easier on the 640K than 5 will.

 

[Al Hartman]

That's why I was thinking DOS 5.00...

 

[vwestlife]

I'm thinking of using MS-DOS 5.0 when I install the mass storage. Or, would DOS 3.3 be better?

IBM's PC DOS 7.0 uses less RAM than any version of PC or MS-DOS after 3.3, so if you want to upgrade an XT class system above DOS 3.3, I consider it to be the ideal choice.

Using a clean boot from floppy, here's the amount of free RAM (out of 640K) that I got with these versions:

PC DOS 2.00 ... 630,672 bytes
PC DOS 2.10 ... 630,672
PC DOS 3.10 ... 616,432
MS-DOS 3.10 ... 616,432
PC DOS 3.21 ... 609,392
PC DOS 3.30 ... 600,528
MS-DOS 3.30 ... 600,368
IBM DOS 5.00 ... 593,328
MS-DOS 5.00 ... 593,328
MS-DOS 6.00 ... 592,256
IBM DOS 6.10 ... 593,056
MS-DOS 6.22 ... 592,256
PC DOS 6.30 ... 593,024
PC DOS 7.00 Revision 0 ... 593,840
PC DOS 2000 (7.00 Revision 1) ... 593,760

 

[Al Hartman]

IBM's PC DOS 7.0 uses less RAM than any version of PC or MS-DOS after 3.3, so if you want to upgrade an XT class system above DOS 3.3, I consider it to be the ideal choice.

For such a tiny gain, I'll stick with DOS 5.00. This Computer is not going to do more than copy disks, and manipulate disk images. I might run some 8-bit emulators on it, but there will be plenty of RAM for that.

 

[Al Hartman]

I received the Flash chip I ordered on eBay today. It was the wrong chip. It didn't work in either board. I ordered two of the correct chip at 3.5x the price of the backordered pair. (4.99 ea. as opposed to $1.36 ea.)

I hate the position of the JP1 jumper on the Lo-Tech card. I can't see the pins when I put my fat little fingers in the case to put it on. I wish it were on the outer edge of the board rather than smack in the center.

I was excited to get my board running, and then after several tries with both boards, I figured out I had ordered the wrong chip. *sigh!*

 

[Al Hartman]

I got the correct two Flash chips today, installed them and flashed the BIOS to both boards. I did one as 8088 XT and the other for my V20 processor. Still waiting for the adapter for my CF card. If I plug it into the Lo-Tech card, it doesn't clear the floppy controller. So, I need the adapter to use a cable.

I tried several hard drives I had. It only saw the one Maxtor drive but DOS 3.3 refused to delete the non-DOS partition. I have to find a newer DOS on 5.25", or a hard drive utility on 5.25".

Next up is to build the "cheapo" interface for my Model 4D.

 

[pearce_jj]

Do you need something to clearing the partition table? I have a utility for that already.

By the way, re JP1: it's only there to provide a means of 'emergency' recovery if a bad flash is written that causes the POST to hang. So usually, the jumper should be left in place permanently.

 

[Al Hartman]

Perfect! I'll give the Wipedisk utility a try!

As for JP1, it gave me a hard time because I can't see what I'm doing, and due to neuropathy, can't feel it either. But eventually I got both boards programmed.

 

[Al Hartman]

Wipedisk worked a treat, and I'm now using a Maxtor 7345 AT hard drive as the boot volume.

When the adapter arrives, I'll try my 8gb CF card.

 

[pearce_jj]

Cool, for is the Maxtor 7345AT running on the Lo-tech ISA CompactFlash adapter?

 

[Al Hartman]

Yes, programmed with the IDE_XTP.BIN I downloaded from your site.

 

[archeocomp]

So does the Lo-tech ISA CompactFlash adapter have XT-IDE functionality ? I had the impression it can only support 8-bit devices, as it is based on XT-CF-Lite. Reading http://www.lo-tech.co.uk/wiki/Lo-tech_ISA_CompactFlash_Adapter_revision_2 does not make it much clearer to me.

EDIT: reading blog http://www.lo-tech.co.uk/lo-tech-isa-compactflash-board/gave me an asnwer. ATA-2 compliant devices support 8-bit transfers. Just wondering how many HDDs out there support ATA-2 ?

 

[pearce_jj]

Answer is, not many. But bear in mind that CF media is very cheap, reliable and fast

As far as I know, Al is the first to run an ATA-2 compliant HDD on the board. I'm glad it works!

 

[archeocomp]

Hi. Could it be possible to attach ATA-2 drive to a 16-bit MultiIO card in an 8-bit slot ? I actually had this idea. Tried MAXTOR 7345AT (not sure it is ATA-2 compliant) with XT-IDE r443 tailored for 16-bit card with no success. Also tried xtide-r566-xt-cf-master-slave BIOS configured in the machine. Config detected 8bit IDE. Tried it but the BIOS did not work with the MAXTOR. I did not even boot from CF card, though it detected the card.