BYTEC/16

Architecture update

Nov

17

2009

At a certain point when microcoding I realized that my architecture was obviously wrong in one aspect. Frankly speaking it was so wrong that I am embarrassed I had not noticed this earlier. The problem was that all address registers were connected to the 8-bit data bus. With such layout, every address loading operation consumed ...

New toys

Nov

15

2009

I have been collecting various stuff I will need to build the computer for some time already. As I am still struggling to complete the microcode assembler (I keep changing my mind on various microcode word structures back and forth), I decided to take a little brake and share photos of what I have gathered. ...

Block diagram

Nov

1

2009

As I am working through the microcode (and the microcode assembler) this finally required me to sketch a block diagram of the entire machine and the CPUs internal datapaths. The microcode is not ready yet (I have completed about 20 most typical instructions), neither is the assembler (I am adding features to the lexer and parser ...

Sequencer tweaks

Oct

19

2009

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 ...

Hewlett-Packard 1631D

Oct

16

2009

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 ...

On microcode sequencing again. Final?

Oct

15

2009

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 ...

Architecture update

New toys

Block diagram

Sequencer tweaks

Hewlett-Packard 1631D

On microcode sequencing again. Final?

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