Denial

... (keyboard, jiffy clock, tape motor control) or the timing of tape load (T1 only) and save (T1 and T2). The VIA #1 timers produce NMIs (mostly for RS232 operations). It is somewhat possible to run standard IEC I/O alongside VIA#2 T1 IRQs, however as the KERNAL does block IRQs at certain time-critical ...

Framing error is confirmed.

To fix, I just stored $01 to NINONE ($A9) right after the call to OPEN ($FFC0) and all is well!

If this caused the bits of the first byte to be shifted one to the left (like what an ASL would do for example) it would result in the byte value being multiplied by two. Check the contents of RSSTAT ($0297) after receiving the first character, I bet you have $02 indicating a framing error. You sho...

Very interesting comments about RS232 in this post: https://sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?p=119706#p119706 RINONE ($A9), the flag used to record when a start bit is received is not initialized when an input channel ...

probably off by a bit? make sure both sides are using same parity & stop bits settings i imagine

... RS-232C device and waits for characters. I have a terminal set for 1200 baud connected to COM4 and I have the same settings in the VICE Userport RS232 section. The program displays the hex value of any character typed on the terminal keyboard. On program restart, the value of the first character ...

... and thus effectively also allocated for BASIC. In $90..$FA is where the KERNAL I/O mostly does its things for keyboard, screen, tape, IEC, RS232; with some of the addresses shared between tape, IEC and RS232. Anything that could in the widest sense be regarded as implementation of a language ...

... KERNAL fitted, neither the other way round it is. Not only makes this the screen window off-center, but also the timing values for jiffy clock and RS232 Baud rates are completely off. A program really can't be expected to operate under such screwed-up circumstances. :) I'm going to have a rummage ...

... just a VIA 6522 default value on Power up? I'm asking because you may change these addresses apparently without problems at least if you don't use RS232 software, and these values do not change even if you reset the machine but only if you switch off the Vic-20, so how is supposed to use these ...

Thanks !

Sorry for the necro-post but I was looking through this thread and tried to download the final RS232 fix from srowe, but unfortunately the link is now broken. Does anyone have a copy of the file that they could post here for posterity and idiots like me? Oops, I missed ...

Sorry for the necro-post but I was looking through this thread and tried to download the final RS232 fix from srowe, but unfortunately the link is now broken. Does anyone have a copy of the file that they could post here for posterity and idiots like me? I'm looking at ...

... (especially not unrelated stuff) unless absolutely necessary for the modifications to work. So JiffyDOS somewhat deliberately removed the Tape and RS232 routines to make room for the new routines of the faster IEC protocol. Use of tape or RS232 triggers an ?ILLEGAL DEVICE NUMBER error with JiffyDOS. ...

... no good idea - not only are the VIC registers wrongly initialised, but the jiffy clock also gets wrong timer values, and the timer constants for RS232 are also different!

There's also the NMI ( N on M askable I nterrupt), which normally processes the RESTORE key as one of its sources. The RS232 routines in the KERNAL are another 'customer'. The corresponding vector resides at ($0318) - be warned: getting an own NMI routine working is already very advanced ...