Model 100 PCSG / Holmes Engineering Chipmunk software disk imaged.

[IBM Portable PC]

I recently dusted off a Model 100 and a Chipmunk drive I purchased from eBay about 6 years ago, having owned a Model 100 previously in 1984-5.

After enjoying success with a couple of floppy drive emulators in other vintage computers a couple of years ago, I thought that I would now try upgrading the Chipmunk to the same type of drive emulator, as a means of transferring files from and to my MacBook i.e. the floppy drive emulators simply work with FAT32 flash drives.

This weekend I have managed to boot the Chipmunk (It contains CDOS Ver 3.43B - I will dump the ROM in the near future) although the floppy drive motor fails to start, either due to the drive itself or to a faulty 12v power supply circuit on the Chipmunk’s controller board. The drive’s NICAD battery pack was also dead, however after some research I have learned that the same type of battery back is used in some emergency exit lights and so is readily replaceable. Having said that, battery power is not a priority for me at present. Holmes Engineering also removed the labels from all chips and so any significant logic repairs on the Chipmunk board would be very difficult. Hopefully someone has a schematic?

My Chipmunk came with 2 floppy disks. One is the original utility disk supplied by PCSG/Holmes Engineering, either with the drive or as an option, while the other was not labeled. I have imaged both disks with my KryoFlux. and the images can be downloaded from here: Public - Google Drive I have also uploaded an OCR'd PDF of the manuals which I received with the drive.

I have not yet accessed any version numbers or dates and so it is likely that others on this list may have newer or older versions of these files. Links to other versions would therefore be appreciated.

 

[Reaperducer]

Good luck with your project. It's been a number of years since anyone made a solid state replacement for the 100's disk drive. The last one that I remember involved a bunch of wires and an Android phone. Obviously, not ideal; and not nearly as elegant as most floppy drive replacements like the SD2IEC and the like.

 

[IBM Portable PC]

Good luck with your project. It's been a number of years since anyone made a solid state replacement for the 100's disk drive. The last one that I remember involved a bunch of wires and an Android phone. Obviously, not ideal; and not nearly as elegant as most floppy drive replacements like the SD2IEC and the like.

Thanks. The circuit Is fairly simply, revolving around a 1770 FDC. Holmes Engineering removed all other chip numbers which makes reverse engineering difficult. However, there are companies who can de-encapsulate the chips and identify the silicon using an electron microscope. I actually know someone who used to do this and will discuss possibilities next week. My primary goal at present is to replace the FDD with an emulator, see this link for my progress to date: https://torlus.com/floppy/forum/viewtopic.php?f=19&t=4274