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Oldest laptop no HD can I run something bigger than the 720k disk. Sharp PC-4501

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Radioguy

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Oldest laptop no HD can I run something bigger than the 720k disk. Sharp PC-4501

The specs I know
Sharp PC-4501 7.16 Mhz DOS Laptop

Sharp PC4501 DOS vintage, collectible laptop, Two-floppy drive system, No HD. 2-3/8 x 5-3/8 high contrast monochrome Supertwist LCD. Uses the 80188 processor, comes with 640 KB of RAM. Comes with a copy of a 720k DOS 5.0 disk. Works with AC-Cord, battery doesn’t seem to hold a charge. plus a 1200 baud internal modem.

I need to run some vintage radio programming software that has a timing routine that renders the program useless on modern pc's. Faster than 286

I finally learned about 720k disks and put tape over my 1.44's and formatted from the dos prompt in XP with FORMAT A: /T:80 /N:9

This made the disks readable in both my newer pentium pc and my old laptop.

I put the software on the 720k disk. when I run the setup program (hdinstal) for the software on the sharp laptop to install on the second floppy drive it wants 800k space. I need the 25 pin serial port to run to a RIB. a box that connects old gm300 motorola radio to pc.

How can I most easily run this radio software program? By using the parallel port to a drive somehow?

I like the old thing its just kind of cool and I dont really want to mod it. I just need a portable DOS based computer to program gm300 radios and run software that won't quite fit on a 720k floppy.

any good work arounds? I am oviously not a system builder.

Thanks Rob

HD , 720k 3.5 floppy, external HD, parallel port HD, 80188
 
I've got one of those! I haven't really done anything with it. I do however use another oldie with only one 720 drive - so it's not because of the space. :)

I don't have a direct solution for you. Perhaps you can delete a file or two to make it work. Some files like readme's may not be needed. However, an important point here is that 720 and 1.44 disks have media with different magnetic requirements. It is not just a matter of the hole and you will run into trouble with reliability. I suggest you get the proper disks. :) You can search this forum for more information because it is a commonly discussed problem.
 
I actually asked for somethin g familiar once - and I got very good answers, for using the parallel port for a drive.

What was recommended to me was a Microsolutions Backpack CD-Rom drive. Hooks up to the parallel port.
 
If you can lay your hands on a parallel-to-SCSI adapter, such as the Adaptec MA-458, you can hook anything from a hard disk drive to a CD-ROM to your laptop. You can also use something like MS-DOS Interlink to transfer from an existing DOS-Based PC over the parallel port (other versions of the same idea exist, including LapLink, Norton Commander, etc.).
 
I just looked at mine and see that it has what looks like a modem connection and also a connector for an external floppy driver. According to the only literature I have, it came with one floppy drive and an optional second, so I don't know if the external can be used as a third drive.

I have forgotten what voltage this thing likes so that is why I didn't plug it in right now. Would you be so kind as to post that? Also, do you have any documentation? I've only been able to find a single advertisement as a jpeg.

Edit: @MikeS - The ad says it comes with 256KB RAM, expandable to 640KB. Yes, a RAMdisk would be great. :)
 
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Radio:

If all else fails, you may want to try a cassette recorder, similar to the hook-up on the Tandy 100 laptop. You know, the ole CLOAD/CSAVE routine. Just a thought. Good Luck!
 
The parallel port is still your best option. Amazingly, the serial port wasn't standard--it was a $99 option!

There's an external 5.25" drive option (360K) and an internal 720K drive option. Not much else, other than memory expansion.

The interesting thing about this thing is that it uses the NEC V40 CPU.
 
Thanks so much for all the replies.

Power supply / wal wart specs for sharp pc-4501

From the back of the power supply/adaptor
Sharp ac adaptor ea-451v
in 120 v ac 60hz 23w
out 10v dc 1.2 A
positive outside of plug center is negative.

Hope that helps.

I guess I will try to use something through the parallel port maybe. It seemed like SCSI controllers used to be really high $

parallel-to-SCSI adapter I'll take a look. There is laplink on the dos disk I have for it. That disk is 2dd. I will have to look for some 2dd disks.

I may have a bead on a 286/386 desktop that I can use to try to install the software on a bigger disk and then try to delete some files that are not used during programming and copy that to a 720k disk to use in the laptop.

If I don't find a way to use an external drive reasonably I may just have to stick to a desktop I may be able to get this week. Not sure until I look at it what the real specs are.
I need a 286 or 386 20mhz or less with DOS and a serial port and HD.
It still blows my mind how small the disks and drives were. Its like archaeology.
A fun but sometimes frustrating puzzle.

Rob
 
For the parallel-to-SCSI, you want a Trantor T348, Adaptec MA348 or MA358. The first two are basically the same product under different names; the third is an improved version that works with bidirectional parallel ports as well. Drivers abound.

The good news is that you don't have to worry about 286-specific instructions with the V40 CPU in your system.

You could also try a parallel port drive, such as a ZIP or Sparq drive if you have one around.
 
My suggestions are ignored again... sighh ;-)

Any reason why you don't want to try Drivespace? Only takes a few minutes to try and oughta give you close to 1MB depending on what you put on it.
 
Mike, I think your suggestion is a good one--but even at 1MB, a single-floppy system is hugely limiting, not to mention awkward (I used one for a time and thought the second drive was heaven sent. No more "insert the disk with COMMAND.COM" messages at the end of every program.)

Nobody's ignoring you, we're just trying to figure out a good way to get tens and hundreds of megabytes online.
 
Chuck(G) said:
Mike, I think your suggestion is a good one--but even at 1MB, a single-floppy system is hugely limiting, not to mention awkward (I used one for a time and thought the second drive was heaven sent. No more "insert the disk with COMMAND.COM" messages at the end of every program.)

Nobody's ignoring you, we're just trying to figure out a good way to get tens and hundreds of megabytes online.
Click to expand...
LOL ;-)

It just seemed that if all the OP needs is a little more than 800K to just run one specific application then compressing the diskette would be a lot quicker and easier than finding/buying some external storage/drivers, etc., but no one was suggesting it.

And I think it's a two-drive system, so it isn't too bad running off floppies.
 
I wonder if Radioguy found a solution using this machine or if he got another one with a bit more space. Radioguy, are you still there? :)

Meanwhile, I've been playing with mine and am starting to like it! I can dialup my ISP and use telnet and other small tools. So far I've used it for BBSing with some success, but I'm still working on other internet functionality. I could of course do e-mail but that's boring. Telnet can do e-mail too, but I have been trying to use wget and view the text based weather information from a local remote weather station. I can't seem to get that to work, but I'm still trying. 1200 baud is a bit trying, but it is actually very useful in making me feel grateful for what I normally use. :)
 
Thanks for askin
Still here. I guess I'm going to settle for a desktop 286/386 . Hopefully one will show up at my thriftstore contact soon. Just not going to try this without an internal HD. Its too hard to get the drivers and make something run on something that old. It will be easier to pull radios out and bring them to a computer with HD. Maybe someday a 386 notebook with windows 95 or older will fall in my lap. Till then thanks for your suggestions. I'll download some early DOS games so I can demo the old Laptop and show that a computer did actually run with a floppy drive smaller than a picture from a camera phone. I would have never known there were 720k disks versus 1.44 if I hadn't tried.


Rob
 
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