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boards:sbc:sbc_v2:minimum-build [2018/07/08 10:54] b1ackmai1er [Use MAX232 alternative.] |
boards:sbc:sbc_v2:minimum-build [2019/06/10 11:10] (current) b1ackmai1er [Use flash memory instead of UV-erasable EPROM] |
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| Line 33: | Line 33: | ||
| * X1 (32768 Hz crystal) | * X1 (32768 Hz crystal) | ||
| * C9 (bypass capacitor) | * C9 (bypass capacitor) | ||
| - | |||
| ===== NVRAM Controller ===== | ===== NVRAM Controller ===== | ||
| Line 48: | Line 47: | ||
| * U22 (Max232) | * U22 (Max232) | ||
| * C24-C28 (1uF capacitors) | * C24-C28 (1uF capacitors) | ||
| - | * Bridge | + | * Bridge |
| + | * Bridge pins 14-11 and 13-12 in the Max232 component position if hardware flow control is required. | ||
| Examples of minimum connections required: | Examples of minimum connections required: | ||
| Line 58: | Line 58: | ||
| {{https:// | {{https:// | ||
| - | |||
| - | |||
| ===== Component Substitution ===== | ===== Component Substitution ===== | ||
| Line 65: | Line 63: | ||
| ==== Use flash memory instead of UV-erasable EPROM ==== | ==== Use flash memory instead of UV-erasable EPROM ==== | ||
| - | Flash memory is generally cheaper, easier to obtain, and easier to work with. It could be instantly erased, without UV eraser lamp, it doesn' | + | Flash memory is generally cheaper, easier to obtain, and easier to work with. It can be instantly erased, without UV eraser lamp, it doesn' |
| ^Device - Jumper^Size^K1^K6^K8| | ^Device - Jumper^Size^K1^K6^K8| | ||
| ^AT29C020^256Kb|1-2|2-3|None| | ^AT29C020^256Kb|1-2|2-3|None| | ||
| + | ^AM29F040B^512Kb|1-2|2-3|2-3| | ||
| + | ^AT49F040A^512Kb|1-2|2-3|2-3| | ||
| + | ^SST39SF040^512Kb|1-2|2-3|2-3| | ||
| + | ^M27C4001^512Kb|1-2|1-2|None| | ||
| ^AT27C080^1Mb|1-2|1-2|1-2| | ^AT27C080^1Mb|1-2|1-2|1-2| | ||
| ^M27C801^1Mb|1-2|1-2|1-2| | ^M27C801^1Mb|1-2|1-2|1-2| | ||
| + | |||
| + | In the situation that you do not have an EPROM programmer it is best to obtain a copy of the ROMWBW in a FLASH format so it can be reprogrammed in-system using the FLASH utility. A HOTFLASH technique can be used if you want to swap from an EPROM to a FLASH chip without an EPROM programmer: | ||
| + | |||
| + | Example starting with an AT27C080 EPROM and swapping to a AT49F040A FLASH chip. | ||
| + | |||
| + | - Transfer new ROM image from PC to SBC-V2 secondary storage i.e. SDCard | ||
| + | - Copy FLASH.COM from B: to secondary storage i.e SDCard | ||
| + | - Change to secondary storage directory. | ||
| + | - Remove EPROM | ||
| + | - Change jumpers to suit FLASH chip i.e. K1 unchanged, K6 from 1-2 to 2-3, K8 from 1-2 to 2-3. | ||
| + | - Insert FLASH chip. Insert pin 1 side first to ensure GND had contact first. | ||
| + | - Run FLASH.COM i.e. FLASH /WRITE SBC.ROM | ||
| + | - Reboot | ||
| \\ | \\ | ||
| Line 85: | Line 100: | ||
| ==== Disk storage without ECB backplane and Disk I/O board. ==== | ==== Disk storage without ECB backplane and Disk I/O board. ==== | ||
| - | You can install the 8255 PPI chip, and use the [[https:// | + | You can install the 8255 PPI chip, and use the [[:boards: |
| + | {{https:// | ||
| - | ==== Use CMOS 74HCT or 74AHCT ICs instead of the TTL 74LS ==== | ||
| - | |||
| - | CMOS 74HCT and 74AHCT logic ICs are usually cheaper than corresponding TTL ICs. They are also consume significantly less electricity. Note that some people reported problems with using these parts for ECB buffers / transmitters and also in SBC-188 (particularly using 74HCT373/ | ||
| - | |||
| - | |||
| - | ==== Disk storage without ECB backplane and Disk I/O board. ==== | ||
| - | |||
| - | You can install the 8255 PPI chip, and use the [[https:// | ||
| ===== Crystals and Oscillators. ===== | ===== Crystals and Oscillators. ===== | ||
