TitoTrainer & Titokone

Piirteet ja ongelmat / Features and Problems (UKK/FAQ)

These may be fixed some day, so please send new features and problems to Teemu.Kerola (at) cs.helsinki.fi. Thank you.

Some of these problems will be fixed one day - hopefully.

Puutteet korjataan seuraavaan TitoTrainer-versioon, jahka TitoTrainer'in jatkokehitykseen saadaan uusi Ohjelmistotuotantoryhmä.

TitoTrainer students interface

• 15.10.2009 pushr and popr save and restore registers R0-R6, not R0-R5 as they should. In practice this does not affect any computations, but only makes the activation records one word unnecessarily too large.
• 11.9.2009 Call instruction can not handle addressing modes properly.
  E.g. "call sp, @parf(fp)" will not work when calling a subroutine passed as parameter.
  workaround: "load r1, parf(fp)" and "call sp, r1"
• 8.2.2007 Titokone and TitoTrainer has a problem that addressing modes "(r2)" or "@r2" do not work in a consistent manner. They both should refer to data in memory, with memory address in register r2. Seemingly, the first case works with store instruction and the second case with all instructions (eg., add) reading from memory, but not necessarily vice versa. This is confusing and partly due to original ttk-91 specification problems. (See also note in Finnish below in section Titokone).
  Fix: use always format "0(r2)" whenever such such reference is needed. This way you always have a memory reference with address zero plus current value of register r2.
• 5.2.2007 "Olen myös huomannut TitoTrainerissa sellaisen kummallisuuden, että välillä ohjelmalle tarkoitettu valmis syöte on jotain aivan muuta kuin pitäisi. Jos syötettä ei huomaa vaihtaa käsin tehtävässä mainituksi, ohjelma tuottaa väärän vastauksen."
  
• 22.1.2007 TitoTrainer does not answer at all, or you get warning

Service Temporarily Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Departmental database server (sysdb.cs.helsinki.fi) is down.
Fix: send mail to atk-apu@cs.helsinki.fi, explain the problem and ask them to kick that machine back on. Include in your mail the exact web address used, e.g., http://sysdb.cs.helsinki.fi/t/tkt_koha/titotrainer/www/login.jsp

• 4.1.2007 Titokone Report has table Symbols and contants. Column "Address" should be "SymValue", and column marked "Value" should be "MemValue", and shown only for variables and constants.
  Roundabout: consider Column Address as containing the value of given symbol. This may be an address or not.
  
• 4.1.2007 Titokone Report given after the execution ended does not show students program output.
  Roundabout: develope your program first in Titokone and only then run it in TitoTrainer.
  Fix: display it. (It is available for correctness testing)
  
• 4.1.2007 Missing "svc sp, =halt" will result in warning "Program exection killed after xxx instructions. Likely an infinite loop"
  Roundabout: realize that this warning may also result from missing "svc sp, =halt".
  Fix: change warning to "Program exection killed after xxx instructions. Likely an infinite loop or missing svc halt."
  (Also: make this modifiable text in instructor interface)
  
• 4.1.2007 Program entry window for fill-in problems could be larger than 20 instructions (without slidebar).
  Fix: change it to 40 like in complete program entry window.
  
• 4.1.2007 TitoTrainer feedback cuts of in the middle of printing acceptance Criteria. Titokone Report completely missing.
  See CallR.
  Roundabout: develope your program first in Titokone and only then run it in TitoTrainer.
  
• 3.1.2007 Titokone Report (shown after given program is executed in TitoTrainer) is sometimes incomplete.
  See CallSimpleF or CallF.
  Roundabout: develope your program first in Titokone and only then run it in TitoTrainer.

Titokone

• 26.1.2007 Seuraavat käskyt toimivat ehkä yllättäen eri tavalla : "store r1, (r2)" ja "store r1, @r2", vaikka molempien pitäisi tallettaa r1'n arvo rekisterin r2 osoittamaan muistipaikkaan. Ainoastaan "store r1, (r2)" tekee näin. Jälkimmäinen käsky tekee epäsuoran muistiviitteen ja toimii siten kuten "store r1, @0(r2)", mikä sinänsä on jollain tavoin loogista, mutta ei speksien mukaisesti. Virhettä esittelee seuraava ohjelma:
  
  ----------------------------------------
  testi dc 123
  load r1, =testi
  ; tulostetaan luku r1:n osoitteesta
  load r2, @r1
  out r2, =crt
  ; siirretään luku r1:n osoitteeseen
  load r3, =55
  store r3, @r1
  ; tulostetaan luku r1:n osoitteesta
  load r2, @r1
  out r2, =crt
  svc sp, =halt
  ----------------------------------------
  
  Ohjelma tulostaa mielestäni virheellisesti kaksi kertaa luvun 123, ja luku 55 joutuu muistiin osoitteeseen 123. Vanhalla Koksi-simulaattorilla tämä ohjelma toimii kuitenkin moitteettomasti.
  
  T: Antti Laaksonen