Z80 instruction set bug found!

To: CALC-TI@LISTS.PPP.TI.COM
Subject: Z80 instruction set bug found!
From: "Thomas J. Hruska" <thruska@TIR.COM>
Date: Sun, 29 Jun 1997 18:45:40 -0400
Reply-To: "Thomas J. Hruska" <thruska@TIR.COM>

Hello,

  For those who are learning ASM (just like me) I found a bug in the Z80
instruction set (the one written by Johnathan Bowen, modified by Robert
Taylor).  Look at LDIR.  The # sign (referenced at the bottom of the
document) means BC=BC-1, DE=DE+1 (NOT DE=DE-1).  If it weren't this way,
the OShell-82 "Graphbuf Test 1" program would have a serious problem...the
calculator would crash.

Signed,
Thomas J. Hruska

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