IBM Model 5150 Personal Computer

Specifications

Yes, the machine that started it all. Before the clones and Windows, there was this machine. It has Microsoft Basic in ROM which starts if there's no disk to boot from. Unique to this model is a tape port at the back, a feature that was removed from all subsequent models. After some research, I have discovered that this has the second revision motherboard which allows a maximum 256k of RAM to be installed on board. It only had 64k of RAM when I got it and I upgraded it to 128k soon afterwards by installing more 4164 DRAM chips. It took me years to get off my arse to upgrade it to its maximum of 640k by having the full 256k on the motherboard and adding an ISA card with an additional 384k.

I had previously upgraded it by adding an IBM branded 10M MFM hard drive but have since removed it as its startup current was a bit much for the computers puny power supply. As it was so long ago since the upgrade, I have no idea what happened to the floppy drive and it may possibly be "in a box somewhere". I bought another and have installed it, bringing it back to its original state as a floppy only system. It may seem a bit odd not having a hard drive, but I used the same kind of setup in the mid-to-late 90's when I was writing assembly language programs for school on a dual floppy 8088 system salvaged from a friends garage. Firing this thing up brings back a lot of memories.

One thing that I wasn't aware of until I revisited this machine in 2017 was that this particular specimen was made in Australia. I didn't even know that IBM had a factory here yet, in plain black and white, a sticker on the rear states that it was made in Wangaratta. Whoah!

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