[Simh] PDP8, Adventure, and SIMH

[Johnny Billquist]

On 2013-04-02 18:45, Rick Murphy wrote:
> At 02:12 PM 3/29/2013, Rob Doyle wrote:
>
>> I just noticed that my PDP8 FPGA implementation differs from SIMH
>> when dealing with mixed/lower case text.
>>
>> I also checked the operation on David Gesswein's online PDP8 and the
>> operation of a real PDP8 matches the operation of my PDP8 FPGA and
>> differs from SIMH.
>>
>> I did use exactly the same RK05 disk image for both SIMH and the PDP8
>> FPGA. The image for the real PDP8 /could/ be different.
>>
>> I'm guessing that SIMH intentionally forces upper case because I didn't
>> do anything special to the PDP8 FPGA. I didn't see any SIMH
>> configuration options to change this.
>>
>> Is this intentional?
>
> The option you're looking for is
> set tto 7b
>
> That will stop the case folding.

I haven't looked, but I don't think that is the issue. The "old" ADVENT 
for OS/8 had the text in all uppercase in the database. So, if you get 
lowercase output you have a different database than the one I'm familiar 
with.

Also, ADVENT runs under the FORTRAN IV runtime system, which does not 
use any OS/8 device drivers, thus any options set in OS/8 are unlikely 
to have any effect.
FRTS is like its own operating system. It runs with interrupts, and do 
most I/O on its own. It also have a FPP8 emulator, since most all code 
from FORTRAN IV is actually FPP8 code, and not PDP8 code. This also 
means that things runs way faster if you actually have a FPP8 in your 
machine.

	Johnny