ALTERNATE DISK STORAGE

The Heathkit H-8 and H-89 computers use hard sector disks for storage. Hard sector disks can still be found but are fairly expensive. A couple alternate storage options that work with the Heathkit 8 bit computers are shown below.

The HSFE can be purchased by clicking on the ADD TO CART link below. To view your order and to check out with PayPal click on the VIEW CART button.

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SEMI-VIRTUAL DISK

The SVD was invented by Eric Rothfus. It is one of the most used devices with my Heathkit computers.

Basically the SVD is a gadget that allows you to upload disk images to the onboard RAM so that you can use these images with your computer. Disk images are simply copies of a disk stored in files on your modern day computer. The standard format for Heathkit disk images is the H8D format. You can create disk images on your PC computer by using 2 free utilities. See my H8DUtility page for details.

 To use the SVD with your Heathkit computer you plug one end of the SVD into your disk controller and the other end into a COM port on your PC. You use the PC-side SVD control panel to upload images to the SVD and the Heathkit computer thinks it's talking to a floppy disk drive.

The following photo is a fully assembled SVD PCB.



I generally don't use a power adapter with my SVDs anymore. Instead, I modified the power input so that I can use a typical ATX style disk drive power plug as shown below:



The simple mod in the above photo allows me to put the SVD inside my H8-2000 case and power it with the MiniATX power supply.

I have builds of the SVD firmware to allow it to run on different PIC micro controllers. See the links below for the complete collection. To build the firmware from the source code use Microchip's MPLAB IDE V8.10 or later.

SVD Firmware Source Code

V2.3 for 16C74B PICs
V2.3 for 16F877 PICs
V2.3 for 16F884 PICs

V2.4 for 16C74B PICs
V2.4 for 16F877 PICs
V2.4 for 16F884 PICs

SVD Firmware HEX files ready to burn to a PIC chip

V2.3 for 16C74B PICs
V2.3 for 16F877 PICs
V2.3 for 16F884 PICs

V2.4 for 16C74B PICs
V2.4 for 16F877 PICs
V2.4 for 16F884 PICs

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HARD SECTOR FLOPPY EMULATOR

The HSFE was invented by Chris Elmquist specifically for the Heathkit computers. It may also work with other vintage computers that used 10-sector disks too but to my knowledge this has not been tested. The HSFE is a device that "emulates" the hard sector index pulses so that you can use commonly available 3.5" soft sector media and 3.5" floppy drives. The hard sector controller card in your Heathkit computer thinks it is reading and writing to a hard sector disk.

Below is a photo of the HSFE



One end of the HSFE plugs into your hard sector controller card and the other end plugs into a pair of 3.5" floppy drives. You can then use the 3.5" low-density (720K) media with your Heathkit computer. It works with high-density (1.44MB) media too if you cover up the density hole with black tape. See below for a typical HSFE configuration.



Download the HSFE manual in PDF format here.

To acquire a fully assembled HSFE for your own use click on the link below.

HSFE Fully Assembled (no cables) - $25.00 (plus shipping)

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SEBHC.ORG

May 16, 2010

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