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68000 68030 CPLD FPGA ARM
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The Memory-3 Board
This board provides:
 
4M (2M+2M) ROM

2M or 8M RAM

 
Compatibility

This board has limited compatibility with the 68230 Board. The timer interrupt capability of the 68230 Board cannot be used when this board is present.

 
Operation

By default, when power is first applied or following a hardware reset, the RAM is disabled and the ROM base address is set to 000000h. This is referred to as Mode 0 or BV (Boot Vector) Mode.

The Stack Pointer (SP) will be loaded with the 32-bit address stored in ROM address 000000h and the Program Counter (PC) will be loaded with the 32-bit address stored in ROM address 000004h.

In Mode 1 or RU (RAM Unlocked) Mode the following applies:

The ROM base address is fixed at C00000h.

The RAM base address is fixed at 000000h.

The transition from Mode 0 to Mode 1 occurs automatically when an address anywhere in the Mode 1 ROM address space (C00000h - FFFFFFh) is read, this action unlocks (enables) the RAM and relocates the ROM.

BV Mode can be disabled if not required.

 
 
 
 
 
 
 
Disclaimer
All hardware designs, software, and information shared on this website is provided "as is"
without warranty of any kind and strictly for personal non-commercial use only.
 
 
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Mega-Micros Home
12 Edgefield Close
Redditch B98 7WB
ENGLAND
 
+44 (0)7973 265572
info@mega-micros.co.uk