30 lines
1.8 KiB
Plaintext
30 lines
1.8 KiB
Plaintext
APPLE ][ Stellation Two "The Mill" 6809 OS/9 daughter-board PCB and Prom code.
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DESCRIPTION
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This project contains schematics and software of a plug-in daughter-board for the APPLE ][ Stellation Two "The Mill" 6809 OS/9 card.
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The daughter-board remaps Apple II ram as seen by the 6909 board to allow execution of Microware OS/9 .
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This is not the original implementation of the Stellation Two daughter-board nor a clone of it.
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The original daughter-board made use of one 74S288 prom and 74LS367 Hex Buffer to create a custom memory mapping.
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The high cost of 74S288 prom burners and the scarce availability of 74S288 proms suggested to implement a different solution.
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Then one ATmel ATF16V8C PLD has been programmed to emulate a prom with the right ram memory mapping combination.
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A switch has been added to allow for normal/OS9 memory mapping selection.
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When installing this daughter-board, chip at location U1 of the 6809 main board (74LS14) must be exchanged with a 74lS04 as recommended in the original Stellation Two OS9 BASIC09 documentation.
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PARTS LIST
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N. Mouser Product n. QTY desc
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556-AF16V8C7PU ATF16V8C-7PU 1 Microchip SPLD 16V8 FAM 300 GATE SPLD STD PWR 7NS
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595-SN74LS04N SN74LS04N 1 Texas Instruments Hex Inv w/HV Output
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855-D01-9922046 D01-9922046 2 Harwin 20P SIL VRT CONN HDR 2.54MM PITCH
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633-A12EH A12EH 1 SWITCH SPDT ON NONE ON 28VDC 28VAC
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DISCLAIMER
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This application (PCB schematic and PROM code) is released under the Creative Commons Attribution-Non Commercial-ShareAlike 4.0 International Public License.
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The Author is not responsible for any direct or indirect damage or any kind of consequence, direct or indirect, should arise from the implementation of this project. |