Msx memory problem

By Shinobi

Expert (125)

Shinobi's picture

05-08-2020, 17:51

Hi

my memory cart of msx ax-200
sometimes it read 12431

and less times reads 28815
Bit A14 is not present in first case...I made a continuity test..the pin reaches from cpu to socket to memory cart to multiplexer inside memory cart and the output of multiplexer that suppose to have A14 output to memory is also making a continuity test correctly..where is the catch??? how msx checks and counts the RAM in xxxx bytes free..
12431 = 11000010001111

28815 = 111000010001111

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By hit9918

Prophet (2896)

hit9918's picture

05-08-2020, 17:58

28815 - 12431 = 16384
the RAM from 0x8000 to 0xbfff is bad. then 16k less is printed.

By Jipe

Paragon (1391)

Jipe's picture

05-08-2020, 20:12

this msx has the same internal configuration as the sony HB500

the memory have upper 32k in slot 0/0 and lower 32k in slot 0/2

see the schematic of HB500 for helping