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==Memory Map==
 
The 16MB of address space will be broken up into 8 2MB chunks by a 74LS138 3-to-8 decoder.
 
The 16MB of address space will be broken up into 8 2MB chunks by a 74LS138 3-to-8 decoder.
  
−
  0MB: 0x00000000 - 0x000FFFFF ROM 1 MB
+
  0MB: 0x00000000 - 0x001FFFFF ROM 2 MB
−
1MB: 0x00100000 - 0x001FFFFF Reserved 1 MB, possible future use for more memory mapped I/O or VRAM, etc.
 
 
  2MB: 0x00200000 - 0x003FFFFF Memory Mapped I/O 2 MB
 
  2MB: 0x00200000 - 0x003FFFFF Memory Mapped I/O 2 MB
 
  4MB: 0x00400000 - 0x00FFFFFF Static RAM 12 MB
 
  4MB: 0x00400000 - 0x00FFFFFF Static RAM 12 MB
  
−
Memory mapped I/O area from 0x00200000 - 0x003FFFFF will be broken down with another 74LS138 into 8 256KB chunks or maybe with a 4-to-16 decoder for 16 chunks.
+
Memory mapped I/O area from 0x00200000 - 0x003FFFFF will be broken down with another 74LS138 into 8 256KB chunks or maybe with a 74LS154 4-to-16 decoder for 16 chunks. I still haven't decided 100% yet.
  
−
Here is my WIP memory decoder showing flash ICs and one SRAM. 74LS138 in lower left will be replaced with a 1-to-2 decoder, I just didn't see one in the component library and didn't feel like adding it.
+
==Device Address Map (74LS138)==
 +
8 chunks of 256KB
 +
{| border="1"
 +
!Device Number||Address Range||Description
 +
|-
 +
|0||0x00200000 - 0x0023FFFF||68901 Multi-Function Peripheral (MFP)
 +
|-
 +
|1||0x00240000 - 0x0027FFFF||Future I/O Device
 +
|-
 +
|2||0x00280000 - 0x002BFFFF||Future I/O Device
 +
|-
 +
|3||0x002C0000 - 0x002FFFFF||Future I/O Device
 +
|-
 +
|4||0x00300000 - 0x0033FFFF||Future I/O Device
 +
|-
 +
|5||0x00340000 - 0x0037FFFF||Future I/O Device
 +
|-
 +
|6||0x00380000 - 0x003BFFFF||Future I/O Device
 +
|-
 +
|7||0x003C0000 - 0x003FFFFF||Future I/O Device
 +
|}
  
−
[[Image:memdec.png]]
+
==Device Address Map (74LS154)==
 +
16 chunks of 128KB
 +
{| border="1"
 +
!Device Number||Address Range||Description
 +
|-
 +
|0||0x00200000 - 0x0021FFFF||68901 Multi-Function Peripheral (MFP)
 +
|-
 +
|1||0x00220000 - 0x0023FFFF||Future I/O Device
 +
|-
 +
|2||0x00240000 - 0x0025FFFF||Future I/O Device
 +
|-
 +
|3||0x00260000 - 0x0027FFFF||Future I/O Device
 +
|-
 +
|4||0x00280000 - 0x0029FFFF||Future I/O Device
 +
|-
 +
|5||0x002A0000 - 0x002BFFFF||Future I/O Device
 +
|-
 +
|6||0x002C0000 - 0x002DFFFF||Future I/O Device
 +
|-
 +
|7||0x002E0000 - 0x002FFFFF||Future I/O Device
 +
|-
 +
|8||0x00300000 - 0x0031FFFF||Future I/O Device
 +
|-
 +
|9||0x00320000 - 0x0033FFFF||Future I/O Device
 +
|-
 +
|10||0x00340000 - 0x0035FFFF||Future I/O Device
 +
|-
 +
|11||0x00360000 - 0x0037FFFF||Future I/O Device
 +
|-
 +
|12||0x00380000 - 0x0039FFFF||Future I/O Device
 +
|-
 +
|13||0x003A0000 - 0x003BFFFF||Future I/O Device
 +
|-
 +
|14||0x003C0000 - 0x003DFFFF||Future I/O Device
 +
|-
 +
|15||0x003E0000 - 0x003FFFFF||Future I/O Device
 +
|}

Latest revision as of 03:44, 4 March 2020

Memory Map

The 16MB of address space will be broken up into 8 2MB chunks by a 74LS138 3-to-8 decoder. 

0MB: 0x00000000 - 0x001FFFFF ROM 2 MB
2MB: 0x00200000 - 0x003FFFFF Memory Mapped I/O 2 MB
4MB: 0x00400000 - 0x00FFFFFF Static RAM 12 MB

Memory mapped I/O area from 0x00200000 - 0x003FFFFF will be broken down with another 74LS138 into 8 256KB chunks or maybe with a 74LS154 4-to-16 decoder for 16 chunks. I still haven't decided 100% yet.

Device Address Map (74LS138)

8 chunks of 256KB

Device Number Address Range Description
0 0x00200000 - 0x0023FFFF 68901 Multi-Function Peripheral (MFP)
1 0x00240000 - 0x0027FFFF Future I/O Device
2 0x00280000 - 0x002BFFFF Future I/O Device
3 0x002C0000 - 0x002FFFFF Future I/O Device
4 0x00300000 - 0x0033FFFF Future I/O Device
5 0x00340000 - 0x0037FFFF Future I/O Device
6 0x00380000 - 0x003BFFFF Future I/O Device
7 0x003C0000 - 0x003FFFFF Future I/O Device

Device Address Map (74LS154)

16 chunks of 128KB

Device Number Address Range Description
0 0x00200000 - 0x0021FFFF 68901 Multi-Function Peripheral (MFP)
1 0x00220000 - 0x0023FFFF Future I/O Device
2 0x00240000 - 0x0025FFFF Future I/O Device
3 0x00260000 - 0x0027FFFF Future I/O Device
4 0x00280000 - 0x0029FFFF Future I/O Device
5 0x002A0000 - 0x002BFFFF Future I/O Device
6 0x002C0000 - 0x002DFFFF Future I/O Device
7 0x002E0000 - 0x002FFFFF Future I/O Device
8 0x00300000 - 0x0031FFFF Future I/O Device
9 0x00320000 - 0x0033FFFF Future I/O Device
10 0x00340000 - 0x0035FFFF Future I/O Device
11 0x00360000 - 0x0037FFFF Future I/O Device
12 0x00380000 - 0x0039FFFF Future I/O Device
13 0x003A0000 - 0x003BFFFF Future I/O Device
14 0x003C0000 - 0x003DFFFF Future I/O Device
15 0x003E0000 - 0x003FFFFF Future I/O Device
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