Hi
SG <enter> turns the sound on key press ON on the MZ80K
SS <enter> turns the sound on key press OFF on the MZ80K
use B <enter> on the MZ80A to toggle the Bell function to test sound is working.
Still faulty 80K
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Re: Still faulty 80K
I managed to transfer the RAMTEST prog using the car cassette adapter, which worked seamlessly. The code printed in the middle of the screen was ( 02032D45 ). However, I would not know where to start interpreting this code. I gather that everything is in Hexadecimal and the last digit is the Row number of the faulty chip, but that is it!!!!
I would appreciate your interpretation. Thanks.
I would appreciate your interpretation. Thanks.
Re: Still faulty 80K
From : viewtopic.php?f=17&t=171
- faulty address in ROW I ranges $1000-$4FFF,
- faulty address in ROW II ranges $5000-$8FFF,
- faulty address in ROW III ranges $9000-$CFFF.
Convert first byte and second byte into binary number. Here $02 -> 00000010b and $03 -> 00000011b so bit 0 mismatches and so the leftmost chip on the ROW I is defective. The least significant bit of a byte represents the leftmost chip and the most significant bit the rightmost chip.
When converting an hexadecimal byte into 8 bits:
D7(rightmost chip)
D6(rightmost chip but one)
D5(rightmost chip but two)
D4(rightmost chip but three)
D3(leftmost chip but three)
D2(leftmost chip but two)
D1(leftmost chip but one)
D0(leftmost chip).
If you have 48KB (3 rows of 16KB):When an issue occurs, it displays in the middle of the display three numbers in hexadecimal: the first [byte in hexadecimal] is the pattern byte tested (bits are inverted), the second [byte in hexadecimal] is the read byte not matching the pattern byte (bits not matching are the faulty chips) and the third [16-bit word address in hexadecimal] is the faulty address to determine which row.
- faulty address in ROW I ranges $1000-$4FFF,
- faulty address in ROW II ranges $5000-$8FFF,
- faulty address in ROW III ranges $9000-$CFFF.
Convert first byte and second byte into binary number. Here $02 -> 00000010b and $03 -> 00000011b so bit 0 mismatches and so the leftmost chip on the ROW I is defective. The least significant bit of a byte represents the leftmost chip and the most significant bit the rightmost chip.
When converting an hexadecimal byte into 8 bits:
D7(rightmost chip)
D6(rightmost chip but one)
D5(rightmost chip but two)
D4(rightmost chip but three)
D3(leftmost chip but three)
D2(leftmost chip but two)
D1(leftmost chip but one)
D0(leftmost chip).
Re: Still faulty 80K
Ahmed is using an MZ-80A so should be 48K. Thanks for the extra info Hlide.
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Re: Still faulty 80K
Thank you for the explanation. I was suspecting from advice given to me by two friends, and bought few of the chips online from ebay. Once arrived I will have to look up someone, not me, to replace it.
Re: Still faulty 80K
I think the RAM chips are socketed rather than soldered so should be fairly easy to pull off the board and clip a new one in. If you're unconfident with hardware, like I am, then you could get a chip removal tool and a chip insertion tool (these are what I use).
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- Posts: 6
- Joined: Thu Nov 26, 2020 5:49 pm
Re: Still faulty 80K
Hi Hlide,
Thanks for the info. I did run the Basic interpreter following the RAMTEST. This time it gave me ( ERROR 6 in 64764 ). Does this correspond to the same chip ( leftmost on Row 1)?
Thanks for the info. I did run the Basic interpreter following the RAMTEST. This time it gave me ( ERROR 6 in 64764 ). Does this correspond to the same chip ( leftmost on Row 1)?
Re: Still faulty 80K
You must run the RAMTEST after each chip replacement until there is no more halt with the hexadecimal faulty pattern and address. Once running, say, a minute, without halting, it means there is no faulty chip found. Then you can try again your BASIC.