Of late, I have been messing with the A1000 NTSC, and have plans to make it boot from ROM instead of the Kickstart load into the WCS. I've been reading through a number of changes that each method wants done. Everything from jumper changes to PAL reprogramming and 74-series logic chips swapped out - the net effect is removing the upper card and RAM, and/or at least rendering it inactive.
While I pondered this over the past few months, and recently poking at the RAM with the Hertel DiagROM, it just occurred to me - what would it take to send this 256K somewhere else in the memory map? I've already got an Insider board that pushes 1.5MB into C00000-D7FFFF.
Open spaces on the A1000 in upper memory exist. E00000-E7FFFF (512K) are known to be available on many machines for extended ROM (used by the Amiga CD units, in particular). There's a nice 256K range from D80000-DBFFFF right above the insider board space before hitting a possible RTC zone at DC0000. There's another chunk at A00000-BEFFFF at the top of the 8MB AutoConfig space. Disclaimer for anyone thinking about this on newer machines - newer chip sets and included motherboard resources consume many parts of the formerly unused spaces, marked Reserved on the Hardware Reference Manuals.
Has anyone recalled a discussion in the past 25+ years about 'relocating' that memory somewhere? instead of rendering it useless when switching to ROM?
Edit note: I am likely going to need DA0000-DBFFFF for the A600-style IDE interface inside this thing, so rule that part of the memory map out.
