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-rw-r--r--src/devices/bus/electron/exp.h146
1 files changed, 73 insertions, 73 deletions
diff --git a/src/devices/bus/electron/exp.h b/src/devices/bus/electron/exp.h
index cfcb7478a10..2f59faec38a 100644
--- a/src/devices/bus/electron/exp.h
+++ b/src/devices/bus/electron/exp.h
@@ -2,84 +2,84 @@
// copyright-holders:Nigel Barnes
/**********************************************************************
- Electron Expansion Port emulation
+ Electron Expansion Port emulation
**********************************************************************
- Pinout:
-
- 18V AC 2 1 18V AC
- AC RETURN 4 3 AC RETURN
- -5V 6 5 -5V
- 0V 8 7 0V
- +5V 10 9 +5V
- 16MHz 12 11 SOUND O/P
- PHI OUT 14 13 13 IN
- NMI 16 15 RST
- R/W 18 17 IRQ
- D6 20 19 D7
- D4 22 21 D5
- D2 24 23 D3
- D0 26 25 D1
- NC 28 27 RDY
- SLOT 30 29 SLOT
- A14 32 31 A15
- A12 34 33 A13
- A10 36 35 A11
- A0 38 37 A9
- A2 40 39 A1
- A4 42 41 A3
- A6 44 43 A5
- A8 46 45 A7
- 0V 48 47 0V
- +5V 50 49 +5V
-
- Signal Definitions:
-
- 18V AC (pins 1,2) - These lines are connected directly to the output from the Electron mains power
+ Pinout:
+
+ 18V AC 2 1 18V AC
+ AC RETURN 4 3 AC RETURN
+ -5V 6 5 -5V
+ 0V 8 7 0V
+ +5V 10 9 +5V
+ 16MHz 12 11 SOUND O/P
+ PHI OUT 14 13 13 IN
+ NMI 16 15 RST
+ R/W 18 17 IRQ
+ D6 20 19 D7
+ D4 22 21 D5
+ D2 24 23 D3
+ D0 26 25 D1
+ NC 28 27 RDY
+ SLOT 30 29 SLOT
+ A14 32 31 A15
+ A12 34 33 A13
+ A10 36 35 A11
+ A0 38 37 A9
+ A2 40 39 A1
+ A4 42 41 A3
+ A6 44 43 A5
+ A8 46 45 A7
+ 0V 48 47 0V
+ +5V 50 49 +5V
+
+ Signal Definitions:
+
+ 18V AC (pins 1,2) - These lines are connected directly to the output from the Electron mains power
AC RETURNS (pins 3,4) - adaptor. A total of 6W may be drawn from these lines as long as no power is
- taken from +5V (pins 9,10,49,50). For safety reasons these lines must never
- be used as an AC input to the Electron.
- -5V (pins 5,6) - A -5V supply from the Electron. Up to 20mA (total) may safely be drawn
- from this line by expansion modules.
- 0V (pins 7,8,47,48) - Ground. Expansion modules with their own power supply must have the 0V
- lines commoned with the Electron.
+ taken from +5V (pins 9,10,49,50). For safety reasons these lines must never
+ be used as an AC input to the Electron.
+ -5V (pins 5,6) - A -5V supply from the Electron. Up to 20mA (total) may safely be drawn
+ from this line by expansion modules.
+ 0V (pins 7,8,47,48) - Ground. Expansion modules with their own power supply must have the 0V
+ lines commoned with the Electron.
+5V (pins 9,10,49,50) - A +5V supply from the Electron. Up to 500mA (total) may safely be drawn
- from this line by expansion modules as long as no power is taken from 18V
- AC (pins 1,2,3,4).
- SOUND O/P (pin 11) - Sound output. A 3V peak to peak source via a 1K series resistor from the
- Electron ULA.
- 16 MHz (pin 12) - 16 Megahertz from the Electron main oscillator. This output may be used
- for clock generation within an expansion module.
- /13 IN (pin 13) - 16 Megahertz divided by 13. This output may be used for baud rate
- generation. If divided by 1024 it will give approximately 1200Hz.
- PHI OUT (pin 14) - The 6502 input clock. The low time is nominally 250ns. The high time may
- be 250ns (2MHz operation when reading ROMs) or 750ns or 1250ns
- (stretched clock for a 1MHz access, the length depending on the phase of the
- 2MHz clock) or up to 40us (if in modes 0-3)
- RST (pin 15) - Reset (active low). This is an OUTPUT ONLY for the system reset line. It
- may be used to initialise expansion modules on power up and when the
- BREAK key is pressed.
- NMI (pin 16) - Non-Maskable Interrupt (negative edge triggered). This is the system NMI
- line which is open collector (wire-OR) and may be asserted by an expansion
- module. The pull-up resistor on this line inside the ULA is 3k3. Care must
- be taken to avoid masking other interrupts by holding the line low. Using
- NMI on the Electron requires knowledge of operating system protocols.
- IRQ (pin 17) - Interrupt Request (active low). This is the system IRQ line which is open
- collector (wire-OR) and may be asserted by an expansion module. The pull-
- up resistor on this line inside the ULA is 3k3. It is essential for the correct
- operation of the machine that interrupts to not occur until the software is
- capable of dealing with them. Interrupts on the Electron expansion bus should
- therefore be disabled on power-up and reset. Significant use of interrupt
- service time may affect other machine functions, eg the real time clock.
- R/W (pin 18) - The system read/write line from the 6502.
- D7-D0 (pins 19-26) - Bi-directional data bus. The direction of data is determined by R/W.
- RDY (pin 27) - 6502 ready line (active low). May be asserted by an expansion module to
- stop the processor when reading slow memory. This line works on read only
- (R/W=1).
- (pin 28) - No connection
- (pins 29,30) - Polarising key connector.
- A0-A15 (pins 31-46) - 6502 address bus.
+ from this line by expansion modules as long as no power is taken from 18V
+ AC (pins 1,2,3,4).
+ SOUND O/P (pin 11) - Sound output. A 3V peak to peak source via a 1K series resistor from the
+ Electron ULA.
+ 16 MHz (pin 12) - 16 Megahertz from the Electron main oscillator. This output may be used
+ for clock generation within an expansion module.
+ /13 IN (pin 13) - 16 Megahertz divided by 13. This output may be used for baud rate
+ generation. If divided by 1024 it will give approximately 1200Hz.
+ PHI OUT (pin 14) - The 6502 input clock. The low time is nominally 250ns. The high time may
+ be 250ns (2MHz operation when reading ROMs) or 750ns or 1250ns
+ (stretched clock for a 1MHz access, the length depending on the phase of the
+ 2MHz clock) or up to 40us (if in modes 0-3)
+ RST (pin 15) - Reset (active low). This is an OUTPUT ONLY for the system reset line. It
+ may be used to initialise expansion modules on power up and when the
+ BREAK key is pressed.
+ NMI (pin 16) - Non-Maskable Interrupt (negative edge triggered). This is the system NMI
+ line which is open collector (wire-OR) and may be asserted by an expansion
+ module. The pull-up resistor on this line inside the ULA is 3k3. Care must
+ be taken to avoid masking other interrupts by holding the line low. Using
+ NMI on the Electron requires knowledge of operating system protocols.
+ IRQ (pin 17) - Interrupt Request (active low). This is the system IRQ line which is open
+ collector (wire-OR) and may be asserted by an expansion module. The pull-
+ up resistor on this line inside the ULA is 3k3. It is essential for the correct
+ operation of the machine that interrupts to not occur until the software is
+ capable of dealing with them. Interrupts on the Electron expansion bus should
+ therefore be disabled on power-up and reset. Significant use of interrupt
+ service time may affect other machine functions, eg the real time clock.
+ R/W (pin 18) - The system read/write line from the 6502.
+ D7-D0 (pins 19-26) - Bi-directional data bus. The direction of data is determined by R/W.
+ RDY (pin 27) - 6502 ready line (active low). May be asserted by an expansion module to
+ stop the processor when reading slow memory. This line works on read only
+ (R/W=1).
+ (pin 28) - No connection
+ (pins 29,30) - Polarising key connector.
+ A0-A15 (pins 31-46) - 6502 address bus.
**********************************************************************/