[astharot]

Are you trying both cards in the PEB at the same time? The TI can use two RS232 cards, but one has to be set for RS232/3 and RS232/4. That might make for a conflict and explain the lockup.

Or perhaps both are set that to 3/4 and you are trying to open RS232/1 or RS232/2. I don't think that would lock the TI up, should just give an Open Error.

If these came from the same system originally, might be something happened to it that took them both out of action. Feel for chips that are running unusually warm. You may be able to compare them with the working card with a digital multimeter.
-Ed

Hello Sodak, i use one rs232 card at time.. i try on PEBOX with no more rs232 board, the fault ras232 crashed how i power on the ti99.. block the autotest card from tms9901 present in ti99 consolle.. i no have a cable for put out the card and test with quiet the electrical signal by oscilloscope or digital multimeter.. here is necessary a real working electrical fix table!! On TI rsr232 i try this experiment.. i upgrade the board using Fred kaal HDX project.. TI99 start ok.. but how i charge the firmware on board go on crash all.. then is fault a IC that work at autostart when power on. You knew this IC i no understant what is.. RS00MMI8249.. seem a custom IC but no know..