Heinz wrote:
Alternate anyone have info on reading out the WD PMOS
roms?
Reading the MICROMs wouldn't be that difficult. But it's not the
whole story. The control chip has two metal-mask PLAs ("translation
arrays") that can cause PC changes even when the current microinstruction
is not a branch, based on two 8-bit translation registers and various
other inputs.
I can envision two ways to dump the translation arrays.
1: Capture a whole lot of logic analyzer traces covering both the
Qbus and the microinstruction bus while executing a variety
of PDP-11 software. Write software to parse the traces,
identify translation branches, track the expected translation
register contents, and build up logic equations. This is a lot
of work and wouldn't be guarateed to come up with identical
PLA equations, though if you run enough traces through you'd
probably get close.
2: Deencapsulate a control chip with fuming nitric acid, take a
high resolution photomicrograph, and spend a lot of time studying
it to figure out the topology of the PLAs.
I've got 3x working M7264 LSI-11/2(quad height)
with all the MICROMs
loaded as well
as a M7270 LSI-11 (dual height), they all run RT fine. Anyone know
if you can just swap the MICROMS to make a WD Pascal Microegine?
You can't, because the translation arrays are different in the LSI-11,
Pascal Microengine, and WD-16. The data path chip of the Pascal
Microengine and WD-16 are the same, but I'm not 100% certain that it's
the same as that of the LSI-11.
Also, the system-level interface of the LSI-11 and Pascal Microengine
are different. There are four bus control signals from the MICROMs that
get decoded for bus control, and they are not used identically in the
LSI-11, Pascal Microengine, and WD-16. Even if you swap the control
chip along with the MICROMs, the Pascal Microengine doesn't know how to
talk to a Qbus.
Eric