84C44X datasheet(29/38 Pages) PHILIPS

29 / 38 page

October 1994

Philips Semiconductors

Product speciﬁcation

8-bit microcontrollers with OSD and VST

84C44X; 84C64X; 84C84X

12.9

Character ROM

Character ROM contains the dot character fonts.

13 x 8 dots are reserved for each character, regardless of

the dot matrix size actually selected.

The dot matrix grid is shown in Fig.28.

Philips provides a software under MS DOS environment

(IBM/PC or compatible) to help customer to design the

character font on the screen and to generate the bit pattern

HEX decimal file automatically.

Contact your local Philips Sales Organization for details.

handbook, halfpage

MCD185

Fig.28 Character ROM.

EMULATION MODE

The emulation mode configuration is shown in Fig.29.

In the emulation mode configuration the PCA84C640's

CPU is disabled and only its derivative logic is active. The

device is controlled by the PCF84C00 bond-out chip. The

PCA84C640's two derivative ports act as additional ports

for the PCF84C00. The interaction between the two

devices is as follows:

1. During the first machine cycle the PCF84C00 fetches

an instruction from EPROM and then decodes that

instruction.

2. During the second machine cycle the PCF84C00

executes the decoded instruction. If the instruction is

related to the derivative ports then DXALE, DXRDN

and/or DXWRN become active and the PCA84C640

operates as a peripheral of the PCF84C00.

3. Depending on the type of instruction executed during

the second machine cycle the following data transfer

happens:

a) During TS1 data from the EPROM is available on

P0.0 to P0.7 which is then available on IB0.0 of the

PCF84C00.

b) During TS4 data from the PCA84C640 can be

transferred to the PCF84C00.

c) During TS6 data from the PCF84C00 can be

transferred to the PCA84C640.

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