Help Needed - Install Driver File for CF Card Support on Sharp PC-3100

CompactFlash on the PC3100

Note: Not all CompactFlash-cards will work in the Sharp. In particular, I do not think that any 3.3V card could ever work. However, most 5V cards below 32MB should now work. I do not know if there are any dual-voltage cards, and if so, whether they would work, but I suspect they should.

I installed the drivers out of sundrv.zip. Don't know whether this is actually necessary, but it is what I did.
I got myself a CompactFlash to PCMCIA adapter. Mine is a noname one, made in Taiwan, no useful markings. I bought mine at Conrad, if you happen to be German. It is a tight fit, and can only be removed with the aid of a pair of pliers, but it does fit.
I inserted the CF-card into the adapter.
I rebooted. With the first card (8MB) the computer would report an invalid card in drive B while booting. This did not happen with the 16MB card. However, both cards could be formated and used just fine (and the computer would not report an invalid card once I formated it).
I ran "sdisk b:"
I ran "sformat b:"
Success!

5.1 RAM vs. storage mode
CompactFlash cards appear to be able to be used in one of two memory modes: RAM or Storage (read on). Storage is what we all use today for CF and SD cards.

RAM mode is part of the PCMCIA standard and in 1991 it was the only way to expand the memory of e.g. a 95LX (CF cards didn't exist yet). You could format RAM as a disk: a RAM disk. They sold so-called RAM cards for that. They require a battery to hold their data. It's described in the 95's manual.

But then Sundisk (the fore runner of Sandisk) invented the CF "standard" as an expansion of RAM mode, amongst other standards for PCMCIA modems etc. (see [2] and [3]). Well, that's the way I see it. So in the beginning (the 1990's) CF cards supported two modes: RAM and Storage. Nowadays we only use Storage memory mode. RAM mode is probably not implemented in CF cards anymore. It's very hard to find an old CF card that can be used in RAM mode. But if you can find such a card then the 95LX's world is your oyster! Never run out of storage space again and never loose data because of battery drain.

CF cards need a driver, though, because the 95 is from before the CF's cards' introduction. Use a serial connection (see separate chapter) to place 3 files on the 95LX (driver, partition- and format utility). The driver can be downloaded from Abraham Moller's website [4]. I recommend:
HP95SDPX.SYS
(notice the X) because it should work with non-Sandisk branded cards too. And this driver version will save to CF even when there's battery low warning. Download official Sandisk utilities to partition and format a CF card on the 95LX itself from Retroisle [5] (they're in a Zip file called SUNDRV.ZIP):
SDISK

SFORMAT

Be sure to use fdisk on Linux to set the partition type to FAT12 (I don't know how this is done on Windows).

To let the 95LX start with a driver do the following (see the Official Manual):

a. Use the Memo app to make a C:\config.sys file.

b. Put in it:
shell = command /p

device = HP95SDPX.SYS

c. Reboot the 95LX (Ctrl + Alt + Del) and type on the command prompt (including the dollar sign!):
$sysmgr

d. Partition and format the CF with SDISK A: and SFORMAT A:.

If you did it right - and if you're very, very lucky - you can now save files to an A: drive.

I've got an old no-name 64 MB card that works well with the 95LX. I've two others that won't.

5.2 Driver
The official driver can be found on the download site I referred to. It supposedly only works with Sandisk/Sundisk branded CF's. Abraham Moller patched this driver to also accept non-Sandisks and to still write to CF if the battery low warning is on. The battery low warning is not in the right: a capacitor on the motherboard fails causing the 95 to constantly complain 'bout the main batteries.

5.3 Fakes?
I bought a 32 MB Sandisk CF card via one of those 2nd hand websites like e-Bay. The sticker says "Sandisk 32 MB" but when I tried to partition it, it appeared to be 64 MB. When I insert this card into the 95 it goes completely berzerk. Crashes like a Led Zeppelin. I suspect this card to be "re-stickered" to be an orig Sandisk 32 MB card from a pile of discarded old broken CF cards. A sticker on the back has "2021" on it. If that stands for the year 2021 then it's most definitely a fake. No 32 MB cards are manufactured anymore. We use GB sized cards nowadays.