I bought my first Sharp PC7100 about 2 decades ago for fun on a fleamarket. At that point the machine was still fully working, including the old 20MB hard disk. But at some point the original hard diks died and i was left with a machine that just prompted an error message.

Over the past several years i have managed to find most of the original user and service documentation for both the PC7000 (dual floppy version) and the PC7100 and those pointed to 2 expansion interfaces for these machines. One with just an aditional hard disk, and one with an ISA backplain that has limited IBM ISA card compatability.

At first, i tried to find one of these expansion boxes but they seemed very rare. And this project was born.

My version of the interface lacks the connections for the original CE700E's MFM hard disk controller, because it is a special controller card to the interface and is not needed for what i use it for.

Because there are these USB to ISA cards that let you use a USB flashdrive as a mass storage device on an XT computer.

In my test system, i use a Gotek floppy emulator as the A: drive to boot a virual boot disk with the driver for the USB card. Once the driver is loaded the USB drive can be used as a hard disk. This driver could just as easily be loaded using the computers normal 5 1/4 inch floppy disk drives.

The current BOM is an edited version from the original service manual, i need to make a proper one at some point, but this one does the trick.

For the interface cable, as long as pin 1 on the PCB and pin 1 on the expansion connector in the PC7000/7100 are connected to pin 1 of the cable it will work. On the PC side, 2 notches should be cut into the IDC connector to make it fit the expansion header.

There is a thread on the VCF forums with more information and a demonstration of the CE700minE.

https://forum.vcfed.org/index.php?threads/sharp-pc7000-7100-expansion-chassis-recreation.1239278/