Skyhigh 15 REU list by Devil/Noice

Some issues back Skyhigh brought a small chapter about reu's (ram expansion units). written by DEVIL of NOICE..

Here Skyhigh can bring a little followup with some small information. also written by Devil...

Ok here we go.

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           ================================
           STATUS = $DF00 (READ ONLY!)
           STATUS = $DF00 (READ ONLY!)
           ================================

Bits 5-7 will be emty after reading

Bit 7: Irq request, will be set when an irq is running.
Bit 6: Set if copy finished
Bit 5: If set, an error has occured during transfer.
Bit 4: Size of reu  (0=512 Kb, 1=256 Kb)
Bit 0-3 : reu version number


                 ===================
                   COMMAND = $DF01
                   COMMAND = $DF01
                 ===================

Bit 7: Start transfer
Bit 6: Reserved
Bit 5: Auto load
Bit 4: Write on $fff0 enable
Bit 3: Reserved
Bit 2: Reserved
Bit 0-2 : Changes transfer  mode

00 C64 --> REU
01 REU --> C64
10 C64 <-> REU (switch)
11 Verify

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CLOB = $DF02
CLOB = $DF02

CHIB = $DF03
CHIB = $DF03

REULOB = $DF04
REULOB = $DF04

REUHIB = $DF05
REUHIB = $DF05

REUBNK = $DF06
REUBNK = $DF06

LGTLOB = $DF07
LGTLOB = $DF07

LGTHIB = $DF08
LGTHIB = $DF08

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                 ===================
                   IRQMASK = $DF09
                   IRQMASK = $DF09
                 ===================

Bit 7: Enables irq while transfering
Bit 6: Holds irq to after transfering
Bit 5: Error in verify


                 ===================
                 BNKLOCK = $DF0A
                 BNKLOCK = $DF0A
                 ===================

Bit 7: Lock c64
Bit 6: Lock reu

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         Written by Henrik 'DEVIL' Hagberg of
                   Noice & Genetic Display