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z80ctrl Front Panel

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J.B. Langston edited this page Aug 11, 2019 · 5 revisions

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
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