On Sun, Apr 5, 2026 at 8:43 PM John R. Hogerhuis <[email protected]> wrote:
> Apoligies if I misunderstand your question... in an interrupt handler you > have to preserve any register you modify including flags... then not only > must the stack be balanced to RET back to a interrupted routine, you also > have to restore flags and registers before you return from interrupt. > Thank you. I think I get it now. I had been wondering why the code was pushing and popping PSW repeatedly inside a loop. Fundamentally, I hadn't thought about the implications of every the Intel 8085 being so limited that every comparison has to go through the A register. Now my biggest question has to do with the "Open handler". The handler implies that accented characters in file names are not allowed > or need to be mapped? That's what I was thinking, but I didn't see how it could possibly work. I just tried using the Norwegian ROM in Virtual T and was quite surprised to see that it translates characters bidirectionally. I get how the Rx Handler works, but it seems what I was calling the "Open handler" is actually a Tx handler as it is somehow translating text I type into TELCOM before it gets sent over the serial port. I must have been mistaken connecting the vector at FB0A to RST 7 + 18h (the Open statement). But I don't don't see anything else in the ROM that jumps to the address at FB0A. I think my next step will be using Virtual T to investigate it, but I'm running into something very peculiar. When I have the Norwegian RS232 hooks installed, any text sent rapidly to the Virtual Modell 100's serial port is getting reversed! [image: !sdrow sesrever reldnah 232SR naigewroN] I thought the problem might be that I was using a FIFO (mknod p) as the "serial device", but it happens even when I use Virtual T's builtin NADSbox. The problem only occurs when the Norwegian RS232 handler is enabled. —b9
