Explicitly Initializing A,B & X Registers

[Dennis Zabawa]

The code snippet starts like this

INIT: 000: 000 000 000 004 RESET: 004: 023 000 LDA 000 006: 123 000 LDB 000 010: 223 000 LDX 000 012: 234 377 STX BUTTONS (CLEAR BUTTONS)

...........

If memory locations 000-002 (Registers A, B & X) are loaded with 000, why do we need to execute three explicit Load instructions to set them to 000? Is this not three bytes of memory wasted?

[Mark Wilson]

The real Kenbak-1 did not clear memory at startup. I added that to the emulation because it seemed useful.  Also CLEAR+STORE does it any time (but sets P=004).

For the verisimilitude of random memory, remove

  // unlike the real thing, clear memory
  ClearAllMemory();

from

void ExtendedCPU::Init()

Mark

[Wayne Verish]

Thanks for sharing.

Sent from the all new AOL app for iOS

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