Friday, 8 July 2016

iMC Portcom II

This is my iMC Portcom II Apple II clone. Its more of a luggable type portable apple II. I purchased this recently off ebay. It looks like its an Apple II plus clone. (not IIe)

It has some power supply issues as it causes my house RCD to trip when I turn it on now. It did have some signs of life for a little while until the power supply failed. The screen is an Amber colour monochrome type.

It has 64k of memory on board and 5 apple slots. The one and only thing I can find on the internet about the iMC Portcom II says that they are slots 0,3,4,5,7. My board does not have any silkscreen on it at all.

It has two ROMs on the motherboard, they are both 2716 eproms (2k x 8). ROM1 is for $F800-FF00. It has just the basics to display the message on the screen, wait for a keypress, and then jump to the disk controller firmware at $C600. The other rom looks like it has the IO card firmware for the disk controller and I assume for the inbuilt serial and parallel ports.

This is my dump of the ROMs and a quick dissassembly of ROM1.
iMC Portcom II roms and dissassembly

I have connected another power supply to test the main board and see if it works. It does, it displays this message now when i turn it on:

The next issue encountered was trying to press a key :-(  The keyboard was unresponsive. This required that the keyboard needed to be opened up. The keyboard encoder has a Z80, 2k eprom and 1k ram. I tried to read the eprom to see if it looked ok, and some bad news. It looks like has been erased over time. (there was no sticker over the window. The reader was not able to read anything useful This will take some reverse engineering to get it going...

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