* * HARDWARE OVERVIEW * *



NOTE: Before use this board it is highly recommended to read the Z8671 Basic/Debug Software Manual to understand how this MCU works together with the provided BASIC/DEBUG environment.


The specs of the RC-Z8BASIC are:

128KB SRAM with battery backup, RS-232 port, serial-USB adapter port, GPIO port, LCD (1602 or 2004) port, User led and key, on-board power supply, ROM emulation mode to enable the "Auto execution at power-up/reset" feature, can be powered from USB or on-board power supply.

Because this board use only a SRAM with a backup battery for data retention, you don't need any legacy EPROM programmer.



It is possible select a ROM emulation mode to use half the SRAM address space as ROM. When the ROM emulation is active it is possible use the "auto execution at power-up/reset" feature of the ROM Basic inside this MCU.

Two different ROM emulation mode are possible. The selection is done with the J7 jumper.

The first time you power on this board (or after changing the SRAM backup battery) you need to do the "INIT PROCEDURE" to set the wanted baud rate (that is stored inside the SRAM).

The RC-Z8BASIC has a RS232 serial port, but there is also a "transparent" serial-USB connector to use a common serial-USB adapter.

It is possible plug a common LCD module (1602 or 2004) into the LCD (J4) connector, but you have to write the low level driver yourself (but I've already written a demo Basic driver for it...). Note that the LCD connector shares some  GPIO of the GPIO (J6) port.

There is also an USER led and a USER key (sharing two GPIO with the J6 GPIO connector too).

You can power the board from the on-board power supply or from USB using a common serial-USB adapter. The selection is made with a jumper (J5). The HW can manage the mixed powering situations when you power the board with the on-board PS (Power Supply) and are using the serial-USB adapter for the serial data link (USB adapter not powered from the host USB while the board is powered, and vice-versa) so you don't need to have care of this detail.


* * J5 AND J7 JUMPERS SETTING * *

J5 (PWR SEL) jumper is used to select how to power the board.
To power from an external 9V power supply (using J1 "DC IN" connector) set a jumper using pin 1 and 2.
To power from USB (using J3 "SER-USB" connector) with a serial-USB adapter (like the one in the photo) place a jumper using pin 2 and 3.

J7 (ROM MAP) jumper is used to select the address space used for ROM emulation when SW3 (ROM EMU) is in the ON position.

The default setting for J7 is pin 1 and 2 "jumped". This corresponds to divide the Z8 64K bytes address space used for programs and data in two half. The low half is ROM (from 0x0800 to 0x7FFF) and the high half (from 0x8000 to 0xFFFF) is RAM.

When pin 2 and pin 3 are "jumped" all the Z8 64K bytes address space used for programs and data is configured as ROM if it is enabled the DM signal (see the manual). This mode is only to make "experiments".

Please note that the total 128K bytes address space is managed by the DM signal (pin 29 of the Z8 BASIC/DEBUG MCU) that selects one of the two 64K bytes pages available, while the "normal" Z8 address space used for the program and data is 64K bytes large. The "second" Z8 64K bytes page can be used when it is enabled the DM function (see the manual) and can be accessed using a couple of assembler instructions.



* * INIT PROCEDURE * *

First time you power on the RC-Z8BASIC you need to do the following "Init Procedure". You need to do this procedure also when you change the SRAM backup battery (CR2032) or every time you power on if there isn't any SRAM backup battery installed.

Because after a reset the Z8 BASIC/DEBUG MCU reads the baud rate at the memory location 0xFFFD (see the manual), you need to write permanently the wanted value in that memory location. But there is only a SRAM here and the content is unknown when powered first time, so the trick...
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