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Epson Research and Development

 

Vancouver Design Center

 

 

4.3 PAL Equations

The PAL equations used for the implementation presented in this document are as follows. Note that PALASM syntax uses positive logic. Active low pins are inverted in the pin declaration section.

CHIP

PCCAPP

PAL16L8

 

 

 

PIN

1

/oe

COMBINATORIAL

; bus

read enable

PIN

2

/we

COMBINATORIAL

; bus

write enable

PIN

3

/ce1

COMBINATORIAL

; bus

low byte enable

PIN

4

/ce2

COMBINATORIAL

; bus

high byte enable

PIN

5

/pcreg

COMBINATORIAL

; bus

CIS cycle enable

PIN

6

breset

COMBINATORIAL

; bus

reset (active high)

PIN

12

/we0

COMBINATORIAL

; S1D13504 low byte write

PIN

13

/we1

COMBINATORIAL

; S1D13504 high byte write

PIN

14

/cs

COMBINATORIAL

; S1D13504 chip select

PIN

15

/rd0

COMBINATORIAL

; S1D13504 low byte read

PIN

16

/rd1

COMBINATORIAL

; S1D13504 high byte read

PIN

17

/reset

COMBINATORIAL

; S1D13504 reset

PIN

10

gnd

 

; supply

PIN

20

vcc

 

; supply

EQUATIONS

rd0 = oe * ce1 * /pcreg rd1 = oe * ce2 * /pcreg we0 = we * ce1 * /pcreg we1 = we * ce2 * /pcreg cs = rd0 + rd1 + we0 + we1 reset = breset

;/pcreg means disable in attribute mode

;/pcreg means disable in attribute mode

;/pcreg means disable in attribute mode

;/pcreg means disable in attribute mode

;inversion appears in pin declaration section

4.4 Register/Memory Mapping

The S1D13504 is a memory mapped device. The internal registers are mapped in the lower PC Card memory address space starting at zero. The display buffer requires 2M bytes and is mapped in the third and fourth megabytes of the PC Card memory address space (ranging from 200000h to 3fffffh).

The PC Card socket provides 64M bytes of address space. Without further resolution on the decoding logic (M/R# connected to A21), the entire register set is aliased for every 64 byte boundary within the specified address range above. Since address bits A[25:22] are ignored, the S1D13505 registers and display buffer are aliased 16 times.

Note

If aliasing is not desirable, the upper addresses must be fully decoded.

S1D13504

Interfacing to the PC Card Bus

X19A-G-009-05

Issue Date: 01/02/02

Page 476
Image 476
Epson S1D13504 manual PAL Equations