bog-dan-ro / ZxR0

ZX Spectrum expansion board base on Raspberry Pi Zero

GNU General Public License v3.0

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How many GPIOs the proxy chip must have? #2

Open bog-dan-ro opened 6 years ago

bog-dan-ro commented 6 years ago

EDGE connector (33 to 37 GPIOs):

Address and data (24 GPIOs):

[x] A00-A15
[x] D0-D7

System Control (4 GPIOs):

[x] MREQ
[x] IOREQ
[x] RD
[x] WR

CPU Control (2 to 5 GPIOs):

[x] WAIT
[x] RESET
[x] CLK ?
[x] INT?
[ ] NMI?

BUS Control (3 to 5 GPIOs):

[x] ROMCS
[x] OE (Upper 4)
[x] OE (Lower 15)
[ ] BUSRQ ?
[ ] BUSACK ?

Voltage (2 pins)

[x] +5V
[x] +GND

Communication with RPi0 (4 GPIOs)

SPI ? (4 GPIOs)

[x] SCLK
[x] MOSI
[x] MISO
[x] SS

JTAG Programing? (4 to 5 pins)

[x] TDI
[x] TDO
[x] TCK
[x] TMS
[ ] TRST ?

a chip with 43 to 48 pins will be needed.