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#FF80 | 58 | CLI | AD | LDA#B001 |
#FF81 | A9 | LDA@#55 | 01 | |
#FF82 | 55 | | B0 | |
#FF83 | 8D | STA#2901 | 10 | BPL#FF88 |
#FF84 | 01 | | 03 | |
#FF85 | 29 | | 6C | JMP(#1FFE) |
#FF86 | CD | CMP#2901 | FE | |
#FF87 | 01 | | 1F | |
#FF88 | 29 | | EA | NOP |
#FF89 | D0 | BNE#FF97 | 58 | CLI |
#FF8A | 0C | | A9 | LDA@#55 |
#FF8B | 0A | | 55 | |
I and a number of others with me using the CX-system, have made the modification below together with a few changes in the Floatingpoint EPROM. After pressing the break key, the text ACORN : ATOM appears on the screen. In case you switch the "old" F-rom active againthe original text is displayed again.
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#FF3F | 2C | 01 | B0 | --- |
BIT | #B001 | |
#FF42 | 10 | 04 | | -- |
BPL | #FF48 | |
#FF44 | 6C | FC | 1F | --- |
JMP | (#1FFC) |
the indirect jump |
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to the bootstrap |
#FF47 | EA | | | - |
NOP | | |
| #FF48 | A2 | 17 | | --- |
LDX | @#17 | |
#FF4A | BD | 9A | FF | --- |
LDA | #FF9A,X | |
#FF4D | 9D | 04 | 02 | --- |
STA | #0204,X, | |
#FF50 | CA | | | - |
DEX | | |
#FF51 | 10 | F7 | | -- |
BPL | #FF4A | |
#FF53 | 9A | | | - |
TXS | | |
#FF54 | 8A | | | - |
TXA | | |
#FF55 | E8 | | | - |
INX | | |
#FF56 | 86 | EA | | -- |
STX | #EA | |
#FF58 | 86 | E1 | | -- |
STX | #E1 | |
#FF5A | 86 | E7 | | -- |
STX | #E7 | |
#FF5C | A2 | 33 | | -- |
LDX | @#33 | |
#FF5E | 9D | EB | 02 | --- |
STA | #02EB,X | |
#FF61 | CA | | | - |
DEX | | |
#FF62 | 10 | FA | | -- |
BPL | #FF5E | |
#FF64 | A9 | 0A | | -- |
LDA | @#0A | |
#FF66 | 85 | FE | | -- |
STA | #FE | |
#FF68 | A9 | 8A | | -- |
LDA | @#8A | |
#FF6A | 8D | 03 | B0 | --- |
STA | #B003 | |
#FF6D | A9 | 07 | | -- |
LDA | @#07 | |
#FF6F | 8D | 02 | B0 | --- |
STA | #B002 | |
#FF72 | 20 | D1 | F7 | --- |
JSR | #F7D1 | print |
#FF75 | 06 | 0C | | -- |
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(a modified |
#FF77 | 0F | |
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opening-text) |
#FF78 | 41 | 43 | | AC |
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ACORN : ATOM |
#FF7A | 4F | 52 | | OR |
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#FF7C | 4E | 3A | 41 | N:A |
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#FF7F | 54 | 4F | 4D | TOM |
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#FF82 | 0A | 0A | | -- |
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#FF84 | 0D | A9 | B2 | --- |
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#FF87 | 85 | 12 | | |
STA | #12 | |
#FF89 | 58 | | | - |
CLI | | |
#FF8A | A9 | 55 | | -- |
LDA | @#55 | |
Using the CX-system, the Floatingpoint Eprom
should also be changed as below.
Short; look at #1000, if there is a routine starting with
#40 and #BF, if yes jump to #1002.
There starts the software for the CX-switching-system.
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#D4AF | AD | 00 | 10 | LDA | #1000 |
#D4B2 | C9 | 40 | | CMP | @#40 |
#D4B4 | F0 | 0A | | BEQ | #D4C0 |
#D4B6 | AD | 01 | A0 | LDA | #A001 |
#D4B9 | C9 | BF | | CMP | @#BF |
#D4BB | D0 | 83 | | BNE | #D440 |
#D4BD | 4C | 02 | A0 | JMP | #A002 |
#D4C0 | 4C | 02 | 10 | JMP | #1002 |  |
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