emu48-mirror/PROBLEMS.TXT

Known bugs and restrictions of Emu48 V1.66
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- the following I/O bits aren't emulated (incomplete)
  DTEST   (0x102) [VDIG LID TRIM]
  DSPCTL  (0x103) [LRT LRTD LRTC BIN]
  LPD     (0x108) [LB2 LB1]
  LPE     (0x109) [GRST RST]
  CMODE   (0x10A) Mode register
  IOC     (0x110) [ERBZ]
  RCS     (0x111) [RX RER RBZ]
  SRQ1    (0x118) [ISQR]
  SRQ2    (0x119) [LSRQ]
  IRC     (0x11A) [IRI EIRU EIRI IRE]
  LCR     (0x11C) [LBZ LBF]
- the baudrates 1920, 3840, 7680 and 15360 aren't emulated on most
  operating systems
  Windows 95a                  1920, 3840, 7680 work, 15360 fail
  Windows 98, NT4.0, 2000, XP  all baudrates fail
- problems when receiving a break signal on the serial port
  Windows 98, NT4.0 SP4 no retrigger on port open
  Windows 98 timing problems setting the RER bit
  Windows 2000 SP2 no known problems
- System-RPL commands VERYVERYSLOW, VERYSLOW and SLOW depends on PC
  speed (are realized as simple down counter in ROM)
- display updating differs from the real machine
- screen VBL counter values may skip after large display operations
  like turning on or updating the whole display
- read on an unconfigured address (open data bus) will not show the
  same value like a real calculator
- the Yorke hardware signals BEN and DA19 aren't fully supported,
  because the emulator don't use a multiplexed AR18 / NCE3 data line
  -> all programs that run on a real calculator will run as well,
  programs with incorrect DA19 / BEN handling may run on the
  emulator but will crash on a real calculator
- incomplete reset logic of the bank switcher FF, on real
  calculators a reset happen after about 4s in deep sleep, in the
  emulator this happens immediately
- no MP interrupt on card control circuit or timer restart
- Shell OS: clock isn't synchronized with real time
- HP49G: the flash memory is emulated now with some restrictions
  - no flash programming times, the flash state machine returns
    immediately the ready signal
  - only one write buffer, second not needed because of prior reason
  - not fully tested, especially the status byte may return
    incorrect values (error bits)
  - quitting the emulator while programming the flash isn't allowed,
    because the content of flash state machine isn't saved so far

06/20/23 (c) by Christoph Gie<69>elink, c dot giesselink at gmx dot de