z80ctrl Front Panel

Proposal

The desire is to have a front panel similar to the Altair 8800 but customized for the z80ctrl/RC2014 and using low-cost parts. The layout would fit on a project box such as this one. Tayda also has inexpensive switches and buttons that I plan to use for the front panel

Layout

--------------------------------------------
 S    S    S    S    S    S    S    S
 7    6    5    4    3    2    1    0
 L    L    L    L    L    L    L    L    B
A15  A14  A13  A12  A11  A10  A9   A8   DAH
 L    L    L    L    L    L    L    L    B
A7   A6   A5   A4   A3   A2   A1   A0   DAL
 L    L    L    L    L    L    L    L    B
D7   D6   D5   D4   D3   D2   D1   D0   DD
 L    L    L    L    L    L    L         B
BR   BA   WAIT HALT RST  INT  NMI       INC
 L    L    L    L    L    L              B
MEM  IO   M1   RFSH RD   WR             DEC
 B    L    B         B    B    B    B    B
CLK- CLK  CLK+      R/D  RST  BRK CONT STEP 
-------------------------------------------

• L = LED
• S = toggle switch
• B = button

LEDs

• A0-A15 = address bus
• D0-D7 = data bus
• CLK = clock
• BR = busreq
• BA = busack
• WAIT
• HALT
• RST = reset
• INT = interrupt
• NMI = non-maskable interrupt
• MEM = memory request
• IO = IO request
• M1 = machine cycle 1 (opcode fetch, interrupt acknowledge)
• RFSH = refresh cycle
• RD = read request
• WR = write request
• TX1 = transmit 1
• RX1 = receive 1
• TX2 = transmit 2
• RX2 = receive 2

Switches

• 0-7 values to deposit on address/data bus
• R/D = run/debug mode

Buttons

• INC = increment address
• DEC = decrement address
• DAH = deposit address high byte
• DAL = deposit address low byte
• DD = deposit data (write to memory)
• C- = clock slower
• C+ = clock faster
• RST = reset and jump to current address
• BRK = set breakpoint at current address
• STEP = step one instruction
• CONT = continue until breakpoint

Connections

• LEDs will be connected directly to bus signals via a buffer
• buttons and switches will be read using z80ctrl I/O expander card