- Reverse-engineering the interrupt circuitry in the Intel 8086 processor (righto.com)
Interrupts have been an important part of computers since the mid-1950s, providing a mechanism to interrupt a program’s execution. Interrupts allows the computer to handle time-critical tasks such as I/O device operations. In this blog post, I look at the interrupt features in the Intel 8086 (1978) and how they are implemented in silicon, a combination of interesting circuitry and microcode.
- A tricky Commodore PET repair: tracking down 6 1/2 bad chips (righto.com)
In 1977, Commodore released the PET computer, a quirky home computer that combined the processor, a tiny keyboard, a cassette drive for storage, and a trapezoidal screen in a metal unit. The Commodore PET, the Apple II, and Radio Shack’s TRS-80 started the home computer market with ready-to-run computers, systems that were called in retrospect the 1977 Trinity. I did much of my early programming on the PET, so when someone offered me a non-working PET a few years ago, I took it for nostalgic reasons.
- Benchmarking Basic on Vintage Computers (techtinkering.com)
There are a few machines I’m quite interested in comparing so I decided to create a simple Basic benchmark to get an idea of their relative speed. The benchmark tests 7 aspects and is inspired by qsbb, which is included with the qlay Sinclair QL emulator. The Basic source code for all the machines tested is available in the GitHub repo. I chose Basic because it was available on all the machines I wanted to test and because the versions I created for each machine would require few changes.
- Commodore PET (Wikipedia)
The Commodore PET is a line of personal computers produced starting in 1977 by Commodore International. A single all-in-one case combines a MOS Technology 6502 microprocessor, Commodore BASIC in read-only memory, keyboard, monochrome monitor, and, in early models, a cassette deck.