PDP-8 Adventure on FPP-12 - who's the "local wizard"?

Rick Murphy rick at rickmurphy.net
Thu Mar 12 20:34:27 CDT 2009


At 08:16 PM 3/12/2009, Philipp Hachtmann wrote:
>Hi folks,
>
>I tried to build and run adventure from Rick Murphy's website:
>http://www.rickmurphy.net/adventure.html
>
>I used the disk image from the page and booted my machine from it.
>
>I was able to compile and link everything by means of COMPIL.BI and 
>LOAD.BI.
>When I want to start the game, I'm asked for the file locations. Then 
>it takes a few seconds (perhaps half a minute?) until the program 
>tells me about "Fatal error 8" - and that I should consult my "local 
>wizard". But who's the local wizard?

I may be as close as you'll get. :-)

"Fatal Error 8", usually means the database is corrupt. Look at 
INITAD.FT for the "CALL BUG(8)" lines;

This specific error unfortunately means two different things.
One is triggered when the record being written to the database is past 
the calculated record number. (Just past label 1020, 'IF (RECORD .GT. 
FILSIZ) CALL BUG(8)".

The other is "LOCATION HAS COND BIT SET TWICE". That's definitely 
something not calculating what was expected.

The other is just above label 1071, "IF(BITSET(LOC,K))CALL BUG(8)".

If the first is being hit, I don't understand what's happening. The 
latter, however, calls a function (BITSET) that's some optimized FPP 
code. There's a chance there's something there that works with the FRTS 
emulator but not with a FPP-12.

>On SIMH it seems to work.

Yup, since there's no FPP hardware.
Unfortunately, I don't have a real machine with a FPP-12 or FPP-8A so I 
can't say if the code works on the real iron or not.

>At the moment, I would like to know if it's my machine and it's FPP-12 
>or the software (perhaps not expecting the presence of a real FPP-12?) 
>which has the problem.
>
>SIMH doesn't have a FPP, so I cannot test it :-(
>
>I successfully ran maindec-12-dafpa-a-pb (FPP-12 data test) on my 
>system. Compiling small FORTRAN IV programs und running them with the 
>FPP attached seems to be working correctly as well.
>
>So are there any known problems?
>Might there be any problems?
>Is the adventure game tested with a real FPP-12?
>Does anyone know an emulator with FPP-12?
>
>My system configuration (abbreviated):
>
>* PDP-8/e
>* 32K memory
>* TD8E DECTape controller
>* RK8E RK05 controller
>* Teletype
>* Some serial ports for Kermit and dumprest
>
>If anyone knows anything, please let me know!
>It would be very good to be sure if I have a hardware problem or not.
>Don't want to search for a phantom problem.
>
>Best wishes,
>
>Philipp :-)

What you could do to start is to figure which of the two bug(8)'s 
you're hitting. Doing a simple edit to INITAD.FT and rebuilding will 
tell me that, then we can go from there. The first one (at label 1020) 
should have been a call to BUG(2).

Another thing you can do is to try it with the FPP-12 disabled.
To disable the FPP, change FRTS location 12621 from 6555 to 7200, then 
try running your ADVENT.LD.

If that fixes it, it's pretty strong indication that the FPP isn't 
matching the built-in emulator. That doesn't mean the FPP is broken, 
unfortunately. I'd like to troubleshoot if possible - send me private 
e-mail and we can try to discuss it.
         -Rick




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