Re: Tornado Computer Unit - Any info around?

Erik Baigar wrote:

Erik Baigar wrote:

Erik Baigar wrote:

Reverse-engineered more commands and updated my
assembler. Now the following commands work:

SUB, ADD (subtracts or adds a memory location to
accumulator register)
CLRA (clear accumulator)
STA (stora accumulator to memory location)
SHL, SHR (shift accumulator left or right one
or more bits. This command includes some
strange arithmetics which I have not jet
fully understood)
INC (increment memory location by one)
RJMP, RJAN(relative jump and relative jump if
accumulator is not negative, i.e. bit11=0)
OUT (transmit data via MIL-STD bus, i.e. plugs
DPL01-DPL04)
LDI (load index register, the next instruction is
done relative to this register - thereafter
the register is set to zero again).


Following additional commands discovered:

MSRTA Moves the hidden bits of the extended shift register
(see posting regarding SHR and SHL from yesterday) to
the accumulator (Move Shift Register To Accu).


Discovered a last instruction in the non-IO-area: MATSR which moves the accumulator to the hidden shift
register. There exist 16 bit-patterns which do
the same action on electrical signal level...


LDA Loades accumulator with direct value out of core
memory. This is a two-word-instruction!!


Now there are only few bit-combiations left which have
to be investigated regarding CPU-commands (IO-commands
are identified but lots not analyzed now). The unit is
still missing instructions for logic operations like
AND, OR and XOR. This is somewhat strange, isn't it?

Scanned the remaining area of bit patterns which are
not known commands now and they do not change accumulator,
hidden shift register or any memory location. There are no IO commands here, too. So indeed there are no AND,
OR and XOR instructions on this box. A call instruction is missing as well (even PDP8 had something like a CALL).
Somewhat strange instruction set...



It sounds like they intended to access In/Out ports via
some selected memory addresses?

Memory reads from I/O space address return a switch setting (or 8?)

Memory writes to the same address could turn on lights, or some such.

For what it's worth...

.

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