When I started writing first microcode and sketching the overall block diagram I decided to tweak the microcode sequencer again a little. Here’s what has changed. Fetch. The 9-bit base address points to two 256-element pages. Addresses in page 00h-FFh store instructions directly visible to programmer, whereas page 100h-1FFh is reserved for pseudo-instructions which are ...
My 1631D logic analyzer and digitizing oscilloscope arrived yesterday. I bought it on US eBay a few weeks ago for as little as $70 (plus $40 shipping to Poland). The thing scared me at first with all the cables, buttons and… its size – it takes one third of my desk! Also, my wife looked ...
I’ve changed my mind on microcode sequencing. Again. Ok, I know I would be fired if all this was for real, but I don’t like the sequencer design with ‘next’ field embedded in the microcode word anymore. The problem is with the ‘next’ field itself which I planned to be longer that 8 bits. This requires not ...
I bought some HP 4N54 hexadecimal displays some time ago at a surplus store. I plugged them into my breadboard just to check them and they all worked fine so I will use them as my debug displays when I start construction. This device fits the purpose very well for a couple of reasons. First ...
