FLASH ON ROM MICROBEES

[someone]

... 74LS273 is a good choice for the high address bits, as a RESET can force all outputs to ZERO.

Thanks for the great post.

This is usually best practice but not when working in conjunction with microbee battery backed RAM and PAK ROMS where the battery backed 4042 latch contents should remain intact and in force for PAK ROMS such as WORDBEE so the user can continue editing their document after a power down or keyboard reset.
[This is actually becomes an annoyance when not using battery backup and the contents of the PAK register are unknown after a power up which makes the powerup + 'M' feature becomes a lottery for the uninitiated.]

The DRAM coreboard employs a 74LS174 resettable flip flop for its memory map configuration register to boot to a known state. (i.e. BOOT ROM at %8000 et al.)
The Alpha Plus (aka Premium Series) and 256TC baseboards use a 74LS273 for their APLUS video configuration options register to boot to a known state. (i.e. standard video mode)