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Losing it? How much ram should 65XE show using fre(0)


Mclaneinc

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6502 can only see 64K at one time,  if you have more than that, banks have to be switched in and out.

the OS Rom is 16K and blocks access to the top 16K Ram unless bank switching is used

The Basic ROM is 8K and blocks 8K RAM (this can be bank-switched as well)

That means 40K RAM left, minus a few K for housekeeping stuff.

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Just now, Tickled_Pink said:

No. It's BASIC and the OS taking it up. The 6502 can directly access all 64K. Bank switching only comes into play once you have more than 64K in a machine, such as on the 130XE.

It is possible to temporarily switch off BASIC and the OS area to gain access to that extra 24K RAM.   You do have to be very careful how you do it so you don't lock up the system.   It would require ML routines from a BASIC program.

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2 hours ago, zzip said:

It is possible to temporarily switch off BASIC and the OS area to gain access to that extra 24K RAM.   You do have to be very careful how you do it so you don't lock up the system.   It would require ML routines from a BASIC program.

22kB. The hardware register region cannot be switched to RAM ;)

 

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