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builderpages:b1ackmai1er:sbc-2g-512 [2018/05/18 08:58]
b1ackmai1er [My build dairy]
builderpages:b1ackmai1er:sbc-2g-512 [2018/06/28 10:16] (current)
b1ackmai1er [My build diary]
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 |   \\ Z80 CPU's \\   \\ 10 pcs pack ex aliexpress.com. \\  \\ All same batch. \\  \\ All 20Mhz parts. \\  \\ Datecode: 00'​43|{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​cpus.png?​nolink&​460x345}}| |   \\ Z80 CPU's \\   \\ 10 pcs pack ex aliexpress.com. \\  \\ All same batch. \\  \\ All 20Mhz parts. \\  \\ Datecode: 00'​43|{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​cpus.png?​nolink&​460x345}}|
 |   ​\\ ​  \\ A 27C256 EPROM can be used in place of the original 27C128, they are both pin compatible. The 27C256 used pin 27 (PGM) as an extra address line A14. \\  \\ 27C128 : 16384Kb : 0000h-3fffh \\  \\ 27C256 : 32768Kb : 0000h-7fffh \\  \\ As only 16Kb is mapped into the memory map only half of the 27C256 can be used. Address line A14 needs to be tied high or low. The SBC-2g-512k board already has A14 tied high to VCC. \\  \\ The only adjustment that needs to be made is to ensure the EPROM is programed starting from 4000h instead of 0000h. i.e the top half is used.|{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​sbc-2g-512/​sbc-2g-512-eprom.png?​nolink&​460x405}}| |   ​\\ ​  \\ A 27C256 EPROM can be used in place of the original 27C128, they are both pin compatible. The 27C256 used pin 27 (PGM) as an extra address line A14. \\  \\ 27C128 : 16384Kb : 0000h-3fffh \\  \\ 27C256 : 32768Kb : 0000h-7fffh \\  \\ As only 16Kb is mapped into the memory map only half of the 27C256 can be used. Address line A14 needs to be tied high or low. The SBC-2g-512k board already has A14 tied high to VCC. \\  \\ The only adjustment that needs to be made is to ensure the EPROM is programed starting from 4000h instead of 0000h. i.e the top half is used.|{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​sbc-2g-512/​sbc-2g-512-eprom.png?​nolink&​460x405}}|
-|   \\ The two serial ports are designated TTY-A and TTY-B. On boot up the monitor ROM will issue a message to both serial ports at 115200kbps. \\   \\ Once it receives a space key press from either port it will boot to the main monitor program using that port for future communication. \\  \\ TTY-A has GND and +5V power connections and the board can be powered from a 5V TTL serial USB converter. I found the voltage supply dropped to 4.7v when using this method. \\  \\ TTY-B does not have GND or +5V power. \\  \\ Ensure only one power source is used at a time, either the 2-pin connector or the the serial connector. ​ |{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​sbc-2g-512/​sbc-2g-512-connector.png?​nolink&​460x368}}|+|   \\ The two serial ports are designated TTY-A and TTY-B. On boot up the monitor ROM will issue a message to both serial ports at 115200kbps. \\   \\ Once it receives a space key press from either port it will boot to the main monitor program using that port for future communication. \\  \\ TTY-A has GND and +5V power connections and the board can be powered from a 5V TTL serial USB converter. I found the voltage supply dropped to 4.7v when using this method. \\  \\ TTY-B does not have +5V power. \\  \\ Ensure only one power source is used at a time, either the 2-pin connector or the the serial connector. ​ |{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​sbc-2g-512/​sbc-2g-512-connector.png?​nolink&​460x368}}|
 |   ​|{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​sbc-2g-512/​sbc-2g-512-parts-layout.png?​nolink&​460x368}}| |   ​|{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​b1ackmai1er/​images/​sbc-2g-512/​sbc-2g-512-parts-layout.png?​nolink&​460x368}}|
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 ===== Parts List  ===== ===== Parts List  =====
builderpages/b1ackmai1er/sbc-2g-512.1526648283.txt.gz · Last modified: 2018/05/18 08:58 by b1ackmai1er
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