thefoolonthehill
Experienced Member
I have an IMSAI 8080 and I wanted to know if and how I could use an Apple II+ ascii keyboard as a keyboard on the IMSAI. I have a parallel and serial card for the IMSAI.
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I now have a 25 pin to 9 pin serial connection between my PC and the IMSAI. The only thing I don't know how to do is talk to it with hyperterminal. Is there some kind of bootstrap program I have to toggle into it before I can use the terminal?
3E CE D3 03 : Async mode byte; sets 2 stop, 8 data bits, no parity, 16x bitrate divisor.
3E 17 D3 03 : Command byte; reset error flag, set receive enable, DTR, transmit enable
21 20 00 : Start storing data in location 00 20
06 F8 : Set our byte counter in register B to 248
DB 03 E6 02 CA 0D 00 : Read the USART status, isolate bit 1 (RxRDY) and loop if no data
DB 02 77 : Read the data byte and store it in the next location
3C CA 08 00 : Increment the byte and loop back, restarting the whole thing if FF is read (rubout)
23 05 C2 0D 00 : bump the location we're storing in, decrement our byte counter and loop back if we haven't read 248 bytes
3E CE D3 03 3E 17 D3 03 DB 03 E6 01 CA 08 00 3E 5A D3 02 C3 08 00
Okay, let's take a look at your bootstrap. I'm assuming that you've got the terminal connected to the correct serial port and the bitrate of the terminal matches that of the serial card and you've set the terminal to 8 bits, no parity.
The serial chips appear to be 8251A devices, so your bootstrap would be:
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Here is the simplest bootstrap loader that's printed in the manual. I have keyed it in twice but I was unsuccessful in downloading binaries to the RAM through a serial terminal. Im not sure if it is a problem with the bootstrap or with the file or the connection.
3E CE D3 03 3E 17 D3 03 21 20 00 06 F8 DB 03 E6
02 CA 0D 00 DB 02 77 3C CA 08 00 23 05 C2 0D 00