signed nibble

Ola Fosheim Grøstad ola.fosheim.grostad at
Tue Jan 8 10:32:25 UTC 2019

On Tuesday, 8 January 2019 at 09:30:14 UTC, Patrick Schluter 
>> During the PC revolution I wrote an entire application in 8088 
>> assembly.  Used to know many of the opcodes and cycle counts 
>> by heart like you do, but it's all but a faint memory now.
> I had to lookup the exact cycle counts ;-) . I remember the 
> relative costs, more or less, but not the details anymore.

Heh, I remember they had a friday-night trivia contest at the 
mid-90s students pub (for natural sciences) where one of the 
questions was the opcode for 6502 LDA (or was it NOP?), and I 
believe I got it right. The opcode for NOP is burned into my 
memory as $EA was used for erasing code during debugging in a 
monitor. And it was also the letters for the big game company 
Electronic Arts...

The cycle counts for 6502 are pretty easy though as they tend to 
be related to the addressing mode and most of them are in the 
range 1-5... No instruction for multiplication or division... Oh 
the fun...

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