7 Jan
2003
7 Jan
'03
9:19 a.m.
--- Cameron Kaiser <spectre(a)stockholm.ptloma.edu> wrote:
I wrote:
Thanks. I wasn't home and that was from memory.
I have one or two of these in a parts drawer that I bought from
the local C= dealer when they went out of business. *rummage*
*rummage* Here they are!
Pins 29, 31 and 33 are bent up and connected to pin 21, and pins
26, 27, 28 30 and 32 are bent up and connected to pin 8.
I recommend mounting the results in a machined-pin socket. One of
the two I have here has pin 1 broken off, no doubt from too many
rough deployments.
I also recommend not using one in an Apple II or any design where
*reading* memory locations can cause interesting side effects.
In Commodore hardware, you have to *write* to I/O registers to
make stuff happen; not so with the Apple.
-ethan
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You can also
build a NOP generator (use a second CPU chip) by bending
the appropriate data bus leads up and hardwiring the databus to the
NOP instruction (0xEA?) - You can then use a logic analyzer to monitor
the address bus for stuck bits and the select lines on the MSI chips
to see that they respond at the appropriate times.
Hey, that's pretty slick! Yes, $ea is NOP on the 6502.