Before ROM BIOS Shadowing

[Great Hierophant]

Modern PCs have the option to copy the contents of an EGA, VGA or BIOS ROM to RAM, called shadowing, for better performance. On my IBM EGA and VGA cards, this gives a substantial, if not tremendous increase in performance. On my Pentium II system, I could literally see the text being placed on the screen line by line (if not character by character) on bootup. Of course, this is not the ideal system for these 8-bit adapters.

Was this what it was like in the days before the 386 made ROM Shadowing possible? Text output line by line? Painfully slow graphics? Unlike the later processors, the 8088s and 80286s did not need to insert many wait states for the graphics card to keep in sync. Maybe it was not so painful.

[evildragon]

Well I'm not sure how my 286 does it, because it's currently dead.

But this is how my NEC V30 system does it (fast 8086 clone).

http://www.youtube.com/watch?v=5COsLfbehZw

Note at 2:10 when I load FDISK and it "draws" the screen.. Even on the first pass it doesn't get everything and actually does a second pass.

[Yzzerdd]

Hey, cool vid! Gee every time you guys post a video you sound much different then I had imagined.

Your 8086 IBM is AWESOME! 3GB HDD, audio card, that things got it all. Even the original key! I'll definately be toying with my AT&T to get it even cooler than it is already. It's speeds are impressive, but I think the reason it needs a second pass may have something to do with the drivers it had to load and with the fact it is accessing an external drive, parallel at that. Let me check ye olde IBM 5150, the machine in the vintage spot of my desk, and see what it does. Oh, HEHE, I dont have an HDD on it. Well I am loading a program using ASCII text as graphics.... Mine appears to get it done in one sweep. Very quick loading off floppy.

--Ryan
Sorry if I steered the thread, but that video is just so darn cool.

[evildragon]

Heh, gotta have my storage and sound. ;) (it does have internet too, but that's a different story for a different thread)..

Anyway, I tried disconnecting the external, and FDISK still does a second pass on drawing the screen.. actually, FDISK is the only application that does a second pass.. Note the passes.. Obviously this video is slowed down a lot.

Notice it doesn't even show "Current fixed disk" and the "Enter choice", on the first pass, and magically appears on a second pass. i think there's even a third pass.

http://img.photobucket.com/albums/v395/Evilweredragon/fdiskdraw.gif

[Trixter]

Was this what it was like in the days before the 386 made ROM Shadowing possible? Text output line by line? Painfully slow graphics? Unlike the later processors, the 8088s and 80286s did not need to insert many wait states for the graphics card to keep in sync. Maybe it was not so painful.

It's exactly the opposite: In the early days, ROM was faster than RAM, due to incredibly slow RAM speeds. On my 5160, I can read from RAM at 4 cycles per byte. ROM, only 3 cycles per byte.

In the early days, you wanted stuff to run from ROM.

[Trixter]

Note at 2:10 when I load FDISK and it "draws" the screen.. Even on the first pass it doesn't get everything and actually does a second pass.

That's par for the course, really. I don't see that as slow (in fact, it's pretty fast considering it's using BIOS routines to redraw, and move the cursor as it goes).

[Trixter]

I'll definately be toying with my AT&T to get it even cooler than it is already.

Ways you can have fun beefing up your AT&T PC 6300:


Replace the 8086 CPU with an NEC V30. 20-50% speed boost depending on what you're running.

Try to find the 1.43 BIOS chips (better program compatibility). If not, no big whoop.

Run programs that support the 6300's special 640x400 graphics mode. For example, CSHOW will display B&W gifs at that res (and dither otherwise), and the game The Colony will run at 640x400 as well. (You can get The Colony from freeoldies.com probably). Also, FRACTINT (fast fractal exploration program) will use the special graphics mode, and Microsoft Word for DOS 4.0 and later will use it for on-screen WYSIWYG.

If you don't care about 5.25" floppy compatibility and have a hard drive, flip the DIP switches on the motherboard to enable half-track mode for the floppy drives. You won't be able to read 5.25" regular DSDD 40-track disks any more, but you will be able to format 5.25" disks to 720K (the drives pack 80 tracks onto a disk in that mode). Note: This is only for personal yucks as only 1.2MB drives will then be able to read your disks.

The speaker in the 6300 sucks; read http://www.oldskool.org/guides/speakerrecording to make a cable with alligator clips you can use to clip onto the speaker leads and run it to a set of speakers or a stereo.

Install an 8087 math coprocessor and run some of the more crazy fractals on FRACTINT (see above).

If you're handy with a dremel and have the hard drive model (one floppy drive and one hard drive), cut a vertical 3.5" drive bay into the front of the case, about one inch to the left of the drives. You can then add a second drive, a 720K 3.5".

Install a hardcard for a 2nd hard drive.

Install a Sound Blaster for some audio fun.


Or, you can buy my 6300 off of me, which had all this done to it back in the day and still works perfectly ;-)

[Yzzerdd]

Hmm... I used to have 3 AT&Ts. 1 is a 2nd owner machine, still in commission. Although I have another two, with certain amounts of working parts. One is in WV, so when I get there, I'll be working on that. Once I get those combined, I will have this, based on the parts I already have:

1.43 ROM
1 360K drive, MFM HDD (I will consider the 720K)
4800baud modem
NEC V30
640K RAM, maybe some extended(or is it expanded?) RAM
External HDD

Hey, I will PM you about that system. I thought your description was suspiciously familiar. You wouldnt happen have anything to do with this (http://www.oldskool.org/shrines/diary) would you? I have been wanting to build a system like that for a long time.

--Ryan

EDIT: OMFG I just poked at the "About Me" on your site, and holy Jesus you are the man I have been wanting to meet for a long time. Your story of a 1980s PC (AT&T Personal Computer 6300) touched my heart 2 years ago, and I have never looked at mine the same way again. As a matter of fact, all my vintage machines were promptly put to use. I will definately be contacting you.

[Trixter]

EDIT: OMFG I just poked at the "About Me" on your site, and holy Jesus you are the man I have been wanting to meet for a long time. Your story of a 1980s PC (AT&T Personal Computer 6300) touched my heart 2 years ago, and I have never looked at mine the same way again. As a matter of fact, all my vintage machines were promptly put to use. I will definately be contacting you.

Then you probably won't want to read this (http://trixter.wordpress.com/2008/04/22/beefing-up-your-6300/) or you'll have a violent conniption :-)

Glad you liked the "diary"; it was fun to write. I still anthropomorphize my most nostalgic pieces.

[Yzzerdd]

Oh. I see. Well then, thats depressing. Looks like I get to do it all myself. Dremmeling? Never seen one, but I know what it does.

I've got a math coprocessor in one of my 6300s as-is. I need to buy a few more to enhance my other systems.

--Ryan
(Joke would've worked better on the 1st)

[evildragon]

I want to find a cheap 8087. One that'll work in my 8MHz Model 25..

I have no idea what type to get.

I'm starting a new job this Monday, and will hopefully have some money to make that purchase.

[Anonymous Coward]

You'll need either 8087-1 (10MHz) or 8088-2 (8MHz). I'm pretty sure intel was the only company that produced them, so there isn't exactly a lot of choice involved.

[Trixter]

I want to find a cheap 8087. One that'll work in my 8MHz Model 25..

I have no idea what type to get.

I'm starting a new job this Monday, and will hopefully have some money to make that purchase.

If you watch ebay or vintagecomputer auctions, etc. you should be able to find one 8MHz or faster. AMD was authorized to make them so you might see an AMD 8087-8 as well as all the Intel ones; they're functionally identical.