Geek Palace

Netlist for Z80 with FlashRAM, static RAM and a UART

This is a netlist for my current board as of November 2013, which includes: The memory is split between the ROM (1Mbit FlashRAM) and RAM (32k Static RAM). The z80 can only address 64kb of RAM (ignoring banking for now), so we're using the 7400
NAND as a memory decoder, splitting the memory space in half between a lower 32k of ROM ($0000 to $7fff) and upper 32k of RAM ($8000 to $ffff). The only purpose the 7400
serves on this board is to do this memory decoding.
The UART is providing a simple serial terminal, so none of the fancier signals like DTR/CTS/etc are being used. The UART operates at TTL voltages, but RS232 operates at a
wider range, so a MAX232 is utilised to get it to the right voltage ranges.

The netlist tables will provide the chip, the pin number, the signal name and what it is connected to. The format of the 'connect to' field indicates which device the
pin is connected to, the signal name on that device and the associated pin number. Remember, if a signal begins with a '/' it indicates that the signal
is active low. If a pin is connected to more than one device, or pin, they are separates by commas.
So, "UART /IOW/18, RAM /WE/27" indicates that this pin is connected to the UART, signal /IOW (active low) which is pin 18 on that device, as well as the RAM, signal /WE
(active low), which is pin 27 on that device.

Pin Signal Connected to
 
Z80
27 /M1 N/C
19 /MREQ 7400 AIn0/1, 7400 AIn1/2
20 /IORQ UART /CS2/14
21 /RD UART /IOR/21, Flash /OE/24, RAM /OE/22
22 /WR UART /IOW/18, RAM /WE/27
28 /RFSH N/C
18 /HALT N/C
24 /WAIT Tied to Vcc
16 /INT Tied to Vcc
17 /NMI Tied to Vcc
26 /RESET 740 Ohm resistor tied Vcc, Intermittant button to GND
25 /BUSRQ Tied to Vcc
23 /BUSACK N/C
6 CLK Clock (Arduino)
11 +5v Vcc
29 GND GND
30,31,32,33,34,35,36,37,38,39,40,1,2,3,4,5 A0-A15 Address bus
14,15,12,8,7,9,10,13 D0-D7 Data bus
 
FlashRAM
1 Vpp N/C
31 /PGM N/C
30 N/C N/C
24 /OE Z80 /RD/21
22 /CE 7400/8
16 GND GND
32 Vcc Vcc
2 A16 N/C
12,11,10,9,8,7,6,5,27,26,23,25,4,28,29,3 A0-A15 Address bus
13,14,15,17,18,19,20,21 D0-D7 Data bus
 
Static RAM
20 /CS 7400 DOut/11
22 /OE Z80 /RD/21
27 /we z80 /WR/22
28 Vcc Vcc
14 GND GND
10,9,8,7,6,5,4,3,25,24,21,23,2,26,1 A0-A14 Address bus
11,12,13,15,16,17,18,19 D0-D7 Data bus
 
7400
1 AIn0 Z80 /MREQ/19
2 AIn1 Z80 /MREQ/19
3 AOut 7400 DIn1/13, 7400 CIn1/10
4 BIn0 N/C
5 BIn1 N/C
6 BOut N/C
7 GND GND
8 COut Flash /CE/22
9 CIn2 7400 DOut/11
10 CIn1 7400 AOut/3
11 DOut RAM /CS/20, 7400 CIn2/9
12 DIn2 Z80 A15/5
13 DIn1 7400 AOut/3
14 Vcc Vcc
 
UART
1,2,3,4,5,6,7,8 D0-D7 Data bus
28,27,26 A0-A2 Address bus
9 RCLK UART /BADOUT/15
10 RX MAX232 R1Out/12
11 TX MAX232 T1In/11
12 CS0 740 Ohm resistor Tied to Vcc
13 CS1 740 Ohm resistor Tied to Vcc
14 /CS2 Z80 /IORQ/20
15 /BAUDOUT UART RCLK/9
16 XTAL1 Oscillator/3
17 XTAL2 N/C
18 /IOW Z80 /WR/22
19 IOW Tied to GND
20 GND GND
21 /IOR Z80 /RD/21
22 IOR Tied to GND
23 /DDIS Tied to GND
24 /TXRDY N/C
25 /AS N/C
29 /RXRDY N/C
30 INT N/C
31 /OUT2 LED (Yellow)
32 /RTS N/C
33 /DTR N/C
34 /OUT1 LED (Red)
35 RESET Flying wire (manual pull high for RESET)
36 /CTS N/C
37 /DSR N/C
38 /DCD N/C
39 /RI N/C
40 Vcc Vcc
 
Oscillator
1 N/C N/C
2 Vcc Vcc
3 Output UART XTAL1/16
4 GND GND
 
MAX232
1 C1+ +side of 1uF cap to M232/3
2 Vs+ +side of 1uF cap to Vcc
3 C1- -side of 1uF cap to M232/1
4 C2+ +side of 1uF cap to M232/5
5 C2- -side of 1uF cap to M232/4
6 Vs- -side of 1uF cap to GND
7 T2Out N/C
8 R2In N/C
9 R2Out N/C
10 T2In N/C
11 T1In UART Tx/11
12 R1Out UART RX/10
13 R1In DB9/Pin 3
14 T1Out DB9/Pin 2
15 GND GND, DB9/Pin 1
16 Vcc Vcc
Notes:

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