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My computer stopped outputting video signal via VGA for the BIOS framebuffer after removing DIMM memory modules, and that sounded to be little bit strange because the CPU can directly read the BIOS firmware from ROM and write the framebuffer to VRAM.
The CPU is Intel Pentium G2020 @2.9 Ghz and the motherboard is LENOVO 3485BNG.
Why does this happen?
Kais
Posted 2018-07-08T00:18:19.463
Reputation: 109
1The PC failed POST, power-on self test. That's usually a no-go situation. – sawdust – 2018-07-08T00:42:52.193
1Are you saying you removed the RAM from your computer and now it doesn’t work? That’s kind of obvious, but the BIOS is flash memory. The CPU does all its processing of code in RAM. – Appleoddity – 2018-07-08T01:17:58.560
@Appleoddity I forgot that the code needs to store the buffers of each instruction execution somewhere without overwritting the ROM. Thanks for pointing that out! – Kais – 2018-07-08T08:14:40.633
@Kais "code needs to store the buffers of each instruction execution somewhere" -- There's no such "buffer". Are you thinking of registers, which are not RAM? "...without overwritting the ROM" -- "Overwriting" or simply writing to ROM is futile. That's why it's called read-only. It cannot be written. The contents of ROM are established when the silicon chip was masked during fabrication. – sawdust – 2018-07-09T01:33:42.463
@sawdust Understood. BTW, why do you think that the data stored in each registers isn't a buffer? Do you know the WB (Write Buffer operation of the instruction execution pipeline), it's about writing buffer to its matching register after retrieving it from the ALU execution operation. – Kais – 2018-07-09T08:27:50.747
1The registers aren't nearly enough "scratch space" for the POST to do its work. The POST needs to find, I believe, 64KB RAM (or some similarly small amount) at contiguous addresses or it will just beep at you and be unable to "compute" enough to display anything on the screen. – Jamie Hanrahan – 2018-07-09T14:08:30.880
1@Kais -- The sentence of yours that I quoted is semantically incorrect. Your latest question reduces to an assertion that "data is a buffer', which is nonsense. Arguing about how you think the internals of a CPU work is irrelevant to your post. – sawdust – 2018-07-09T19:49:57.983
@sawdust I seem to have forgot the WB abbreviation: thinking of it as "Write Buffer" instead of Write Back. Thanks for your comment, you're right. – Kais – 2018-07-09T21:24:43.977