Can you do real work with the 30-year-old IBM 5150?

Our intrepid reporter spends a week trying to write, browse the Web, edit photos, and even tweet on IBM's first PC.

By Benj Edwards, PC World |  Hardware, I'll try it, IBM

After careful thought, I sequestered myself in an infrequently used room in the upstairs corner of my parents' house. The bulk of Day 1 consisted of moving equipment over. I needed to take not only the PC itself, but also what seemed like 15 metric tons of supporting hardware that I could use for repairs in case the PC broke. Among those supplies were a few dozen ISA expansion cards (including spare video cards, serial cards, and the like), a couple extra 5.25-inch floppy drives, some tools, and a box of assorted cables.

Day 2: Trying to Fix the Thing

Day 2 began with a general survey of the PC. The first thing I did was open the case and assess what was inside. In the PC's five ISA expansion slots, I found a CGA video card, a memory expansion card, a floppy controller card, and a serial card for communicating with mice and other peripherals. For storage, my PC came equipped with a lone, full-height 5.25-inch 360KB DS/DD floppy drive. Thankfully, someone had maxed out the RAM at 640KB (yep, that's a massive 640 kilobytes--roughly 0.032% of the RAM on today's low-end PCs). When I looked for the processor, I found a surprise: One of this system's previous owners had replaced the Intel 8088 CPU with a Zilog V20 CPU.

The V20, originally designed by NEC, was a pin-compatible enhancement of the 8088 that could run certain programs 30% faster than the 8088 could--even though it ran at the same 4.77MHz clock speed. But it wouldn't be historically accurate to run such a speed demon for this challenge, so I replaced the V20 with an 8088 chip that I had in my collection.

Next, I hooked the machine to my period-authentic IBM 5153 CGA monitor and booted it up. I briefly had some trouble with the video connector on the CGA board, but after I cleaned it a bit, everything worked fine. Then I encountered the next obstacle: a bad RAM chip. The POST error code told me exactly which RAM chip was bad (okay, I cheated and looked it up on the Internet using a netbook I had with me). Luckily, this socketed chip (a 4164C, to be precise) could be easily swapped out--but I didn't have a replacement on hand.

Despite the malfunctioning RAM, the machine seemed to work well. The 5150 contains, as the Apple II did, a full version of BASIC in ROM that loads right up if you don't boot from a disk.


Originally published on PC World |  Click here to read the original story.
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