This is most likely the same as (or at least mostly similar to) the Memory Interface on the Flipper chip (see YAGCD).
These registers are used by some programs (running on Broadway) to perform indirect accesses on the Memory Controller registers. The Memory Interface is also exposed to Hollywood starting at 0x0d8b4000.

Memory Interface Registers
Address	Bits	Name	Description
0x0d8b4000	16	MEM_MARR0_START	Memory Protection
0x0d8b4002	16	MEM_MARR0_END
0x0d8b4004	16	MEM_MARR1_START
0x0d8b4006	16	MEM_MARR1_END
0x0d8b4008	16	MEM_MARR2_START
0x0d8b400a	16	MEM_MARR2_END
0x0d8b400c	16	MEM_MARR3_START
0x0d8b400e	16	MEM_MARR3_END
0x0d8b4010	16	MEM_MARR_CONTROL	MARR{0-3} permissions
0x0d8b4012	16	MEM_CP_BW_DIAL	Bandwidth Dial (Command Processor)
0x0d8b4014	16	MEM_TC_BW_DIAL	Bandwidth Dial (Texture Control)
0x0d8b4016	16	MEM_PE_BW_DIAL	Bandwidth Dial (Pixel Engine)
0x0d8b4018	16	MEM_CPUR_BW_DIAL	Bandwidth Dial (CPU read)
0x0d8b401a	16	MEM_CPUW_BW_DIAL	Bandwidth Dial (CPU write)
0x0d8b401c	16	MEM_INT_ENBL	MARR interrupt enable
0x0d8b401e	16	MEM_INT_STAT	MARR interrupt status
0x0d8b4020	16	MEM_INT_CLR	MARR interrupt clear/mask (?)
0x0d8b4022	16	MEM_INT_ADDRL	MARR interrupt address (lo bits)
0x0d8b4024	16	MEM_INT_ADDRH	MARR interrupt address (hi bits)
0x0d8b4026	16	MEM_REFRESH
0x0d8b4028	16	MEM_CONFIG
0x0d8b402a	16	MEM_LATENCY
0x0d8b402c	16	MEM_RDTORD
0x0d8b402e	16	MEM_RDTOWR
0x0d8b4030	16	MEM_WRTORD
0x0d8b4032	16	MEM_CP_REQCOUNTH	Memory Request Count (Command Processor) (hi bits)
0x0d8b4034	16	MEM_CP_REQCOUNTL	Memory Request Count (Command Processor) (lo bits)
0x0d8b4036	16	MEM_TC_REQCOUNTH	Memory Request Count (Texture Control) (hi bits)
0x0d8b4038	16	MEM_TC_REQCOUNTL	Memory Request Count (Texture Control) (lo bits)
0x0d8b403a	16	MEM_CPUR_REQCOUNTH	Memory Request Count (CPU read) (hi bits)
0x0d8b403c	16	MEM_CPUR_REQCOUNTL	Memory Request Count (CPU read) (lo bits)
0x0d8b403e	16	MEM_CPUW_REQCOUNTH	Memory Request Count (CPU write) (hi bits)
0x0d8b4040	16	MEM_CPUW_REQCOUNTL	Memory Request Count (CPU write) (lo bits)
0x0d8b4042	16	MEM_DSP_REQCOUNTH	Memory Request Count (DSP) (hi bits)
0x0d8b4044	16	MEM_DSP_REQCOUNTL	Memory Request Count (DSP) (lo bits)
0x0d8b4046	16	MEM_IO_REQCOUNTH	Memory Request Count (I/O) (hi bits)
0x0d8b4048	16	MEM_IO_REQCOUNTL	Memory Request Count (I/O) (lo bits)
0x0d8b404a	16	MEM_VI_REQCOUNTH	Memory Request Count (Video Interface) (hi bits)
0x0d8b404c	16	MEM_VI_REQCOUNTL	Memory Request Count (Video Interface) (lo bits)
0x0d8b404e	16	MEM_PE_REQCOUNTH	Memory Request Count (Pixel Engine) (hi bits)
0x0d8b4050	16	MEM_PE_REQCOUNTL	Memory Request Count (Pixel Engine) (lo bits)
0x0d8b4052	16	MEM_RF_REQCOUNTH
0x0d8b4054	16	MEM_RF_REQCOUNTL
0x0d8b4056	16	MEM_FI_REQCOUNTH
0x0d8b4058	16	MEM_FI_REQCOUNTL
0x0d8b405a	16	MEM_DRV_STRENGTH
0x0d8b405c	16	MEM_REFRSH_THHD
0x0d8b4060	16	MEM_CPUAHMR_REQCOUNTH
0x0d8b4062	16	MEM_CPUAHMR_REQCOUNTL
0x0d8b4064	16	MEM_CPUAHMW_REQCOUNTH
0x0d8b4066	16	MEM_CPUAHMW_REQCOUNTL
0x0d8b4068	16	MEM_DMAAHMR_REQCOUNTH
0x0d8b406a	16	MEM_DMAAHMR_REQCOUNTL
0x0d8b406c	16	MEM_DMAAHMW_REQCOUNTH
0x0d8b406e	16	MEM_DMAAHMW_REQCOUNTL
0x0d8b4070	16	MEM_ACC_REQCOUNTH
0x0d8b4072	16	MEM_ACC_REQCOUNTL
0x0d8b4074	16	MEM_DDRREG_ADDR	DDR register offset
0x0d8b4076	16	MEM_DDRREG_DATA	DDR register data
0x0d8b4078	16	MEM_DRV_PSTRENGTH

Memory Protection

	Memory Interface
Access
Broadway	Full
Starlet	Full
Registers
Base	0x0c004000
Length	0x80
Access size	16 bits
Byte order	Big Endian
IRQs
Broadway	7
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The MARR registers are used to configure memory protection (where the granularity of particular regions are defined as a chunk of pages). Protected memory is always 1 page long (where page size is 1024 bytes). If the CPU tries to access the protected region in a way that is not allowed, an external interrupt will be raised. Page addresses are calculated with (physical_address >> 10). ^[check]

MEM_MARR0_START (0x0C004000)
	150
Access	R/W

MEM_MARR0_END (0x0C004002)
	150
Access	R/W

MEM_MARR1_START (0x0C004004)
	150
Access	R/W

MEM_MARR1_END (0x0C004006)
	150
Access	R/W

MEM_MARR2_START (0x0C004008)
	150
Access	R/W

MEM_MARR2_END (0x0C00400a)
	150
Access	R/W

MEM_MARR3_START (0x0C00400c)
	150
Access	R/W

MEM_MARR3_END (0x0C00400e)
	150
Access	R/W

MEM_MARR_CONTROL (0x0C004010)
	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Access	U								R/W		R/W		R/W		R/W
Field									Ch3		Ch2		Ch1		Ch0

Field	Description
ChX	00: Access Denied, 01: Read Only, 10: Write Only, 11: Read/Write

MEM_INT_ENBL (0x0C00401C)
	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Access	U											?/W	?/W	?/W	?/W	?/W
Field												ChAll	Ch3	Ch2	Ch1	Ch0

Field	Description
ChX	When set, interrupt from that channel is enabled.
ChAll	When set, all MI interrupts are enabled.

MEM_INT_STAT (0x0C00401E)
	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Access	U											R/W	R/W	R/W	R/W	R/W
Field												ChAll	Ch3	Ch2	Ch1	Ch0

Field	Description
ChX	When set, IRQ has been requested. Writing 1 clears it.
ChAll	All MI interrupts. (?)

MEM_INT_CLR (0x0C004020)
	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Access	U														?	U
Field															Unk

Field	Description
Unk	? Set when MI interrupt has been asserted ? Should be cleared by interrupt handler

MEM_INT_ADDRL (0x0C004022)
	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Access	R/?											U
Field	Low

MEM_INT_ADDRH (0x0C004024)
	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Access	U		R/?
Field			High

Field	Description
High	Bits 29->16 of the address that the protection exception occurred on.
Low	Bits 15->5 of the address that the protection exception occurred on.

Hardware/Memory Interface

Memory Protection