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builderpages:plasmo:z80sbc64 [2018/12/05 09:42]
plasmo
builderpages:plasmo:z80sbc64 [2018/12/12 10:44] (current)
plasmo
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 The heart of the SBC is a 5V CPLD, Altera EPM7064S, that implements the serial port receive function, generates baud clock, interfaces to compact flash, and divides memory into 4 banks of 32KB. The design has no ROM. The traditional ROM software are stored in battery-backed RAM. The serial bootstrap function loads the ROM-equivalent software into RAM when the board is powered up the first time; the system boots off the software in RAM for subsequent power cycles or resets. The ROM-equivalent software are protected by switching to banks inaccessible to normal software. The heart of the SBC is a 5V CPLD, Altera EPM7064S, that implements the serial port receive function, generates baud clock, interfaces to compact flash, and divides memory into 4 banks of 32KB. The design has no ROM. The traditional ROM software are stored in battery-backed RAM. The serial bootstrap function loads the ROM-equivalent software into RAM when the board is powered up the first time; the system boots off the software in RAM for subsequent power cycles or resets. The ROM-equivalent software are protected by switching to banks inaccessible to normal software.
  
-Instead of the EPM7128S, a smaller EPM7064S is used because it is available in PLCC package that can be socketed in 44-pin PLCC through-hole socket. This is the design compromise to enable a hobbyist-friendly board with through-hole components and easy-to-solder surface mount devices. Because of the limited resources on EPM7064S, the memory supported is 128KB with 4 banks of 32KB. Furthermore,​ the serial port transmit function is emulate in software (bit banging).+Instead of the EPM7128S, a smaller EPM7064S is used because it is available in PLCC package that can be socketed in 44-pin PLCC through-hole socket. This is the design compromise to enable a hobbyist-friendly board with through-hole components and an easy-to-solder surface mount connector. Because of the limited resources on EPM7064S, the memory supported is 128KB with 4 banks of 32KB. Furthermore,​ the serial port transmit function is emulate in software (bit banging). 
 + 
 +===== Design information ===== 
 + 
 +{{:​builderpages:​plasmo:​z80sbc64:​z80sbc64_scm.pdf|Schematic}} 
 + 
 +Gerber photoplots, the boards were manufacturered by Seeed Studio. 
 + 
 +Altera EPM7064SLC44 design file 
 + 
 +==== Software ==== 
 + 
 +Z80SBCLD is the bootstrap loader 
 + 
 +ZMon64 is the monitor loaded by the bootstrap loader 
 + 
 +cpm22all is the BDOS/​CCP/​BIOS for CP/M2.2
  
  
builderpages/plasmo/z80sbc64.1544020943.txt.gz · Last modified: 2018/12/05 09:42 by plasmo
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