XTs and large hard disks

[Julian Wolfe]

I'm maxing out the machine for the sake of maxing out the machine.   
The portable is a semi-rare beast; it's an XT in a wierd portable  
case.  I actually bought it as a machine to diagnose car problems  
with via the DIACOM software, but I got rid of the car I was using it  
on! now it's an experimentation box.  I already did the 640K mod to  
the mainboard, bought a 2MB EMS card, I have a 1.44MB floppy  
controller that works as long as only the MFM disk is in the  
system...it won't work with the IDE controller I have, OR the Seagate  
ST02.

What do I have for software on it that I actually USE?
PC-DOS 2000
Wordperfect 5.1
Lotus 1-2-3 2.1
Quicken 6.0 for DOS
Windows 3.0
IBM PC Storyboard
All the Watcom TCP/IP tools I can find
Overland Data Tools for DOS (for backing the thing up to 9 track  
tape, HAHA)
Oh...and I play a few games on it...yes. ;)
I do testing for the MS-DOS Turbo C port of Sarien with it, to make  
sure it runs on 8088/8086.

So to say the machine is "lightly used" would be totally wrong.  I  
beat the silicon out of it.

On Aug 29, 2005, at 10:35 PM, Jim Leonard wrote:

> Wolfe, Julian wrote:
>
>> 1. Does anyone know a good solution for putting a large drive in  
>> an XT,
>> while still leaving it an XT?
>>
>
> IDE with "540MB" (actual capacity is less) drives or less, if you  
> can find an IDE card that works.  I have two (different brands) but  
> sadly I haven't found time to try them yet in my model 5150.  Only  
> other solution is SCSI, something I have had extremely unlucky  
> progress with (boards with BIOSes won't POST; boards that need  
> drivers don't have the damn drivers bundled with the board; etc.)   
> However, I believe my experience with 8-bit SCSI on XT is uncommon  
> compared with the other gentlemen here.
>
>
>> 2. Should I leave the V20 in?  I've heard it has compatibility  
>> issues with
>> some programs, but I'm not solid on my information.
>>
>
> The V20 can enable some ill-behaved programs to work as it  
> implements the "SHL register,immediate" 80186 opcode, and this  
> opcode is sometimes the *only* used opcode used in "286-only"  
> programs.  I was able to run programs claiming they needed a 286 on  
> my AT&T PC 6300 (Olivetti M24 8086 clone) after I upgraded it to an  
> NEC V30.
>
> HOWEVER, the V20 and V30 expand the prefetch queue from 4 bytes to  
> 6 bytes (the source of their speedup) and this screws with timing- 
> sensitive programs such as games, copy-protected diskette copiers,  
> and turnkey stuff like robot controllers, etc. from the early 1980s.
>
> I'm going to go out on a limb and assume that you're expanding your  
> convertable so that it can play most IBM PC games from the  
> 1980s.  :-)  Based on my experience in that context, the V20 will  
> cause the following behavior compared to a factory original 8088:
>
> - 88% of games will run just fine, unaffected by the V20
> - 5% of games will run smoother/better due to the small speedup of  
> the V20
> - 5% of games will run too fast to be enjoyable
> - 2% of games will not run at all
>
> Games are a good example to flush out this kind of behavior because  
> they were usually programmed as close to the hardware as possible  
> to achieve the best performance; also, many copy-protection schemes  
> are timing-based and may fail if the CPU speed is not what is  
> expected.
>
> If I have incorrectly assumed your intentions, please let me know  
> as I'm dying with curiousity :-)
> -- 
> Jim Leonard (trixter at oldskool.org)                    http:// 
> www.oldskool.org/
> Want to help an ambitious games project?             http:// 
> www.mobygames.com/
> Or check out some trippy MindCandy at             http:// 
> www.mindcandydvd.com/
>