I have a mono slab without a monitor or keyboard. I've build a serial lead using the following instructions (
http://www.asterontech.com/Asterontech/NeXT_68040_Serial_Console.html) & powered up the system using a 470ohm resister as per NetBSD/next68k faq (
http://www.netbsd.org/ports/next68k/faq.html#no-monitor)
System turns out & after a moment displays on @ symbol & that's it.
Is there any way of entering the prom over serial console or forcing "port a as alternate console" without access to a monitor & keyboard?
Patching eeprom & reflashing is a possibility but I'm wondering if anything can be done otherwise (key sequence via serial?)
I made the mistake of thinking I was dealing with flash. Long forgetting about eeprom.
I guess my two options are to reverse engineer the firmware image and modify it to enable serial console by default. binwalk & radare do not provide much info at the moment when pointed to /NeXTfiles/Software/ROM_Files/68040_Non-Turbo_Chipset/Rev_2.5_v66.BIN
Second options is to get the y-cable together which allows a mono slab to be connected to a non-adb soundbox and then set it to serial output conventionally.
Does anyone know if the rom format / layout is documented??
Your best bet is probably to examine the previous emulator sources. The values are stored in a 32bit static RAM ( part of the rtc) which is battery backed. Perhaps you could interface to that chip to flip the bit for serial console? I see in the previous sources they already have the crc and layout figured out so you would just need to figure out a way to write to the chip in circuit.
I'll take a look, thanks for the pointer :)