Mar 242014
 

I’ve updated my online assembler IDE recently (more info here). It can assemble / debug code for MCU Motorola 6809. The assembler is in alpha version, not yet fully compatible with old 6809 assemblers (pseudoinstructions like FCB, FCC, BSZ, RMB, ZMB are missing, but I’m working on them). The all you need is to create a file with “.a09” extension and compile it. Compiler outputs to “HEX” files (not S records yet, but it’ll be soon). Assembled code can be tested in embedded 6809 emulator, based on my code. You can use an online SBC09 emulator, which is capable to emulate Grant Searle’s 6 chip simple 6809 computer. Stay tuned for further information…

Jan 032014
 

8080js is Yet Another 8080 Emulator. But why?

Chris Double’s js8080 emulator is pretty good if you want to play around. But it has a really big issues – some instructions simply don’t work, some instructions set the flags totally bad and DAA instruction is probably guessing rather than computing. Stephan Tramm did a pretty good work with his i8080 CP/M emulator. But it is still slightly differrent from original (“silicon”) CPU.

The biggest challenge were two testing software: so-called “Kelly Smith Test” and – the greatest one – 8080 Exerciser (a.k.a. Sunhillow). The first one does some basic tests, it checks known border states and simply says: OK, or Error at… The second one does a lot of combinations of data manipulating instructions, and the result is a set of CRC codes (one for each test case). They are compared with CRCs from real “silicon” CPUs. It checks all non-standard states very well and deeply.

My emulator passed Kelly Smith test a long time ago. But Exerciser was a really big issue. It takes a lot of changes and tests and fixes, but – it works!

So I keep my promise and release this JS emulator as open source library. Here it is: 8080js

PS: Big thanks to Roman Borik for his help.

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