They were suppose to run 24/7/365 and also had magnetic core memory that should retain it data during power off. The PDP-11's I worked with back them had no boot roms.
BATTERY EEPROM WORKS DOWNLOAD CODE
So you really don't need much boot code to get started. A dip switch set which drive, the rest was in that 512 byte boot rom. Single sided, double sided, single density, double density, 5 1/4 or 8". This system only had a 512 byte boot rom yet it could boot scsi hard drives or from floppies. Simple thing that makes using more than 64k easer. One address range could be common between banks so a write to this address range was a write to both banks at the same time. On writes to video ram, the CPU had to wait to sync up to what the video controller was doing so not to glitch the display, and would write to both video ram and normal ram at the same time. On reads of video ram the Z80 was reading normal ram. My old Z80 computer had it's video ram mapped to the same address as normal ram. One idea to keep in mind is that while the CPU can normally read from one location, It could easily write to many locations at the same time.
I've read some articles saying that without a proper backup circuit you can corrupt the ram etc. Do I need to use two to make 6v, and then regulate it with a switcher, or will 3v hold the data usually? Also Is it as simple as connecting a 2032 to the rams VCC and then the 2032 ground to the main board common ground. I know Nintendo games use CR2032 battery's to keep the SRAM backed up, but these chips are 5v, so im wondering how I can use 2032s to back up the SRAM. What I'm wondering is it feasible to just use all the address space with this one chip and battery back it? This way in the beginning I don't need to worry about any latching, glue logic, or burning eeprom/eproms, I don't have an eprom programmer, only UV eraser so I will have to build an eeprom programmer which is a totally separate project. So I have been working on a basic z80 system, I have eproms/eeproms laying around, but Im trying to make this as simple as possible right now.