DragonFly users List (threaded) for 2005-06
Re: Historical use of "traps"
:Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx> wrote:
: > We need a historian. I do remember that on the 6502 instruction code
: > 00 was a BRK instruction. People would often use this to insert hooks
: > into eproms or proms without erasing them.
:On the Commodore PET2001 [*], which was a BASIC computer
:based on the 6502, the break pointer pointed to a hex
:monitor contained on ROM. So it was possible to enter
:the hex monitor by typing the BASIC command "SYS <n>"
:where <n> was an address known to contain 0x00.
:Typically used as in "POKE1024,0:SYS1024".
What, don't you remember the two-button-salute? The little
two-button gizmo you could wire into the machine to generate an NMI
that broke you into the machine language monitor ?
Sometimes I wish I could do that (more easily) on a PC. PCs
have NMIs, but they are not real NMIs, and its a !@#$#@$ to
hook them up.
Actually what I really want is a PCI card that allows me to run GDB
from another box without having to do any code interfacing at all.