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Re: Starting a new board: RC-Z8BASIC [message #6713 is a reply to message #6711] |
Sat, 26 October 2019 01:54 |
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just4fun
Messages: 273 Registered: May 2017 Location: Dark side of the Moon
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Senior Member |
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About "ist nicht nutzbar" I've found an interesting paper about the U8611 (=Z8611)... see the attachment
der U8611 ist ein Einchipmikrorechner, bei dem der interne 4k ROM nicht nutzbar ist:
durch Pegel von 7,35v bis 8V on reset Sprung auf externen Programmspeicher 1012H;
Port 0 und 1 werden für die Adressen- und Datenverkehr genutzt;
So it seems that if it is applied a voltage between 7.35V and 8V on the reset pin, a jump to the 0x1012 external memory location is done...
There is no mention on that on the original Z8611 datasheet...
[Updated on: Sat, 26 October 2019 02:03] Report message to a moderator
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Re: Starting a new board: RC-Z8BASIC [message #6714 is a reply to message #6713] |
Sat, 26 October 2019 04:10 |
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just4fun
Messages: 273 Registered: May 2017 Location: Dark side of the Moon
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Senior Member |
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I've found a Zilog application notes about the Z8 Test Mode that is enabled pulling the RESET pin at Vcc + 2.5V.
See the attachment...
Note that in the "Program B listing" example the program on the external memory starts at 0x0812 as stated on the U8611 sheet for a 2K bytes ROM Z8 chip.
BTW: this can be a way to check if a Z8 ROM-med MCU has a 2K or 4K ROM.. if it jumps to 0x0812 is a 2K ROM model, if jumps to 0x1012 is a 4K ROM one...
Of course you need a LA on A8-A15 (to see a 08H or a 10H) using the AS signal L->H transition as trigger (see the ext mem R/W timing on the datasheet).
[Updated on: Sat, 26 October 2019 10:52] Report message to a moderator
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Re: Starting a new board: RC-Z8BASIC [message #6723 is a reply to message #6721] |
Wed, 30 October 2019 01:42 |
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just4fun
Messages: 273 Registered: May 2017 Location: Dark side of the Moon
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Senior Member |
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Wow... this really change things!
As far I can see this ROM Basic needs an external (assembler) starting routine to make it work.
In the example (see 8.5) it seems that there are three jump vectors:
812H is the "starting" assembler routine;
815H is the jump to the input routine (GET_CHAR);
818H is the jump to the output routine (PUT_CHAR);
So to try to use this MCU with the RC-Z8BASIC it is needed to find a way to put the needed code inside the SRAM...
(but to use easily this MCU with the RC-Z8BASIC changes must be done as a simple SRAM is not enough... probably a "companion" MCU to help to load a generic binary into the SRAM as it seems that the "user case" is radically different and similar to a romless Z8 assumed that an external host is always required...)
BTW: In the example are used three programs to compile (the first should be the assembler, the others utilities):
%bin%\as.exe -L %file%.asm -a
%bin%\p2bin.exe -r $-$ "%file%.p"
%bin%\plist.exe "%file%.p"
[Updated on: Wed, 30 October 2019 11:29] Report message to a moderator
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