DragonFly BSD
DragonFly users List (threaded) for 2005-06
[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]

Re: Historical use of "traps"

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 9 Jun 2005 10:17:55 -0700 (PDT)

: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.

					Matthew Dillon 

[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]