Apple One Replica

Hello,

I was watching Ben Heck's Apple one replica Videos earlier, and he was talking about "Bank 0, and Bank 1" I didn't quite understand what that meant.

Could I get some help?

Top Replies

clem57 over 9 years ago +1

In the early days, memory addressing was limited to 16 bits or 64 K. To store more, they would have a bank 0 and 1 switch at same address by processor command to effectively increase memory by 8 K typically…

clem57 over 9 years ago

In the early days, memory addressing was limited to 16 bits or 64 K. To store more, they would have a bank 0 and 1 switch at same address by processor command to effectively increase memory by 8 K typically.
Clem
Cancel
Vote Up +1 Vote Down

Sign in to reply

Cancel
nick123 over 9 years ago in reply to clem57

Ok, then how does the computer access the ROM?, I thought bank 0 was RAM, and bank 1 was ROM.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
clem57 over 9 years ago in reply to nick123

Usually both are RAM!
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
nick123 over 9 years ago in reply to clem57

Ok, than how is the ROM accessed?
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
clem57 over 9 years ago in reply to nick123

Usually ROM is located in a special memory location where the processor goes after a reset or power on. The code tests memory and sets up keyboard, mouse and display. If anything goes wrong, the number of beeps on speaker signal what hardware failed.
Clem
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
stevenlee over 9 years ago

I could be wrong, but here I go.... Early processers were limited to 65,535 bytes that could be nativly accessed. So if more memory space was desiered there has to be a port the proccesor can goto that swaps access from one "Bank" of memory to another. Where addresses 0000h to 3FFFh might be ROM and 4000 to 7FFFh could be RAM but 8000h to FFFFh coul be swaped out in 32K banks to be extra ROM or RAM. This also refers to How a computer might switch around how it acceses memory depending on it's mode. Like the C64 does.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel