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Corona PPC-400 It LIVES!!!

T

TomFisher

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Nov 8, 2012
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I am literally just getting my feet wet with this and I am so AMAZED by this thing - It's older than I am!

Alright, so here's the details:
I'm using a Corona PPC-400 portable to run IBM DOS 6.3. It has an Intel 8088 processor at I believe 4.77 MHz.

Unfortunately only one of the Mitsubishi floppy drives works and they're only 360K. A 1.44Mb drive brings up a system failure, so does running only one floppy.

What I would like to determine is
- how I can tell what kind of drives are compatible
- what are those expansion slots that look like 1/2 ISA slots
- what kind of software does this thing need?
- how can I increase the RAM (there's rows of empty 14 pin DIP sockets that look promising)

Thanks in advance and pictures will be posted as soon as I can find a functional digital camera.
 
Those 1/2 ISA slots are 8-bit ISA slots--what came before the 5170 16-bit ones.

You can't run a 1.44MB 3.5" floppy without some serious modification, but you can run 720K 3.5" drives. Better yet, pick up an XT-IDE card and run with a hard disk.

I think those 14-pin DIP sockets are really 16-pin DIP sockets for RAM.
 
You use to be able to get 8 bit ISA cards for using 1.44 3.5" drives and 1.2 5.25" drives. I've one in my 8 bit card box for the time when an XT class machine becomes available.
 
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I don't know the Cordata PPC-400 well enough to determine if it's possible to disable the FDC. If so, then there is the XT-FDC project that's ongoing.

I wonder if one could do what the Amiga folks do--run the floppy spindle at half speed to get high-density?
 
Alright, after playing with it for a long time, here's some updates"

Yep, those are 8-bit ISA slots and 16 pin RAM sockets.
The RAM chips it already has are MN4164P 494-15 chips with a triangle logo (Matsushita?)
I was able to get the second floppy working, broken plastic in the locking mechanism. I re-fabricated it with parts from a mechanical pencil (yes it looks ghetto but it works) and now both drives are working.

I notice there are exactly the same amount of RAM slots open as are soldered to the board, so does that mean I can realistically only double the RAM to 512Kb? I saw 8-bit RAM cards on eBay, are these compatible? There's no BIOS splash screen or menu like I'm used to so I have no idea what settings are changeable. Lots of DIP switches and jumpers inside but no markings on the PCB. I guess I need to go find a manual.

I can't believe how nice this computer is to use, I actually use it all the time now. If I can get it to run Word for DOS, and I can get a hold of a suitable drive for one of my desktops, I'll use this thing all the time. It's even more stable than my friend's IBM 5155 albeit a good ten pounds heavier on a good day.

As far as a bigger floppy drive is concerned, any idea on whether or not a 1.2mb 5.25" will work? I don't think I'll be able to slow down the spindle to fool these drives they're SO tolerant of errors, I had the spindle jam on one while writing and as soon as I corrected the problem, the drive happily went back to writing, a disk check revealed that it didn't mess up the data at all -- I was amazed, for the clunkiness of these Mitsubishi drives they really give it their best.

I still haven't located the battery to my D60 so no pics yet, but I've been so entertained, I haven't spent much time looking. :D

Regards,

Thomas
 
That would indeed seem to limit your motherboard RAM to 512K. Not bad for the time--the remainder (to 640K) would have to come from an add-in card.

There was a 5.25" 1.2M drive that could slow to 180 RPM offered by a company called Weltek, but I suspect that they're nearly unobtanium now--they weren't common. So either stick with the 360K drives or install 3.5" drives for 720K or replace the controller.
 
Chuck(G) said:
That would indeed seem to limit your motherboard RAM to 512K. Not bad for the time--the remainder (to 640K) would have to come from an add-in card.

There was a 5.25" 1.2M drive that could slow to 180 RPM offered by a company called Weltek, but I suspect that they're nearly unobtanium now--they weren't common. So either stick with the 360K drives or install 3.5" drives for 720K or replace the controller.
Click to expand...

Why are 720K 3.5" drives so freaking expensive? I'm looking at a 5.25" 720K drive to put in my desktop, I'm wondering if that will work with the Corona. Thanks for all the help your replies have been very illuinating.

Regards,

Thomas
 
I have no idea, since all 1.44M 3.5" drives can be used as 720K. Either use 720K (DS2D) media or cover the density hole in a DSHD floppy jacket--the drive will do the rest. Most 720K drives allow for /READY on pin 34, but that's not important here.
 
Chuck(G) said:
I have no idea, since all 1.44M 3.5" drives can be used as 720K. Either use 720K (DS2D) media or cover the density hole in a DSHD floppy jacket--the drive will do the rest. Most 720K drives allow for /READY on pin 34, but that's not important here.
Click to expand...

I've now successfully gone to 3.5" disks. Thanks again! I had to solder in a proper connector, That was a lot of fun in itself.

One more question, I'm looking at one of those add in ISA memory cards. The chips that plug into those ram slots are like $15 each or I can get a RAM card for $45 that will take the board to 640. My question is can I keep adding memory beyond 640K and run himem in DOS or am I limited to 640k? Then I guess at what point do I need to worry about things like device drivers etc...

Regards,

Thomas
 
I'm not familiar with the internal specifics of the Cordata system, but right off the top of my head, I'd say that you might well be limited to 640K of contiguous RAM. There's a possibility that you might be able to expand this to, say, 768K or even do some infill, but that would require some tinkering.

If you can install non-contiguous RAM, there are ways that it can be used to load some parts of the operating system. EMS/LIM is also a possibility if you have applications that can use it. I suspect that about 90 percent of the EMS boards sold for 8088-based systems were to run Lotus 1-2-3.
 
Perhaps I'm using the wrong term, I guess I meant EMS. Basically, I'm able to use all 64MB or RAM on DOS in my Packard Bell, I wanted to do something similar here.

I was really disappointed when I saw the size of the executable for Lotus 1-2-3, how did anyone afford a computer that could run it? Anyway, I am gonna deck this computer out as much as I possibly can. The system will fit 2 13" cards so I'm thinking of 2 RAM cards eventually. We'll see what happens if I get the first one and it works.

Regards,

Thomas
 
TomFisher said:
. . . so I'm thinking of 2 RAM cards eventually. We'll see what happens if I get the first one and it works.
Click to expand...

Forgive me if I missed something when quickly reading through the tread - but. Remember that the RAM cards will run at bus speed. My first experience with them was very disappointing because I didn't realize that. They can be useful, but they're not quite like actual RAM.
 
Alright, so the Six Pak Plus arrived today and when I installed it and configured it with the DIP switch I see on the screen:
512K Installed
240K Available to DOS

The bottom number is the same as it was before I installed the card.

So I fiddle with every possible switch settings I can imagine, then I even replace the RTC battery. Still nothing. I remove the card.

Next I install the little RAM chips into the sockets on my motherboard. After painstakingly installing one of the two available rows I see:

384K RAM Installed
240K Available to DOS

Again, I still can only see 240K, of which DOS takes A LOT ~53K.

Am I missing something?

Regards,

Thomas
 
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