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The C128 came standard with a Z80 as a secondary processor. (Would have been more useful for me if they'd also had an 8" floppy drive so I could have easily go
by colomon 8y ago
The C128 came standard with a Z80 as a secondary processor. (Would have been more useful for me if they'd also had an 8" floppy drive so I could have easily gotten stuff to my parents' CP/M machine at work.)
- vidarh 8y agoThe C128 is a really bizarre beast - it actually "boots" with the Z-80 in control initially, and uses that to check for a CP/M disk in the drive, a C-64 cartridge in the cartridge port, or if you hold down the Commodore key, and uses that to determine whether to go into CP/M mode, C128 mode or C64 mode on startup... During CP/M operation, some BIOS functionality actually causes a context switch from the Z-80 to the 8502 and back...
- rusk 8y agoThe C128 is a really bizarre beast It really is. It's a fantastic looking machine but the internals are just bonkers. The reason for the internal Z80 was that Commodore had sold all these CP/M plugin cartridges that actually had a Z80 in them, but they drew too much power and the C128 engineers pretty much unilaterally decided it was cheaper to just build in the second chip than sort out the power issue [0]. The story of how this machine was designed and built is quite hair-raising and the likes of which I doubt we'll ever see again! [0] https://www.reddit.com/r/c128/comments/682da4/c128_ama_from_bil_herd/dgvcla9/ https://www.reddit.com/r/c128/comments/682da4/c128_ama_from_...