Author Topic: What's kind of VRAM the PCE has  (Read 247 times)

touko

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What's kind of VRAM the PCE has
« on: July 07, 2015, 02:40:28 AM »
Hi, i was sure that's the PCE's VRAM was a 100 ns SRAM .
A guy tell me that's in fact PSRAM ram at 120ns ..
I am a little bit skeptical,because the hi-res needs a 93ns access RAM .

There are really some problems to do a game in 10.74 dotclock mode, due to VRAM speed ??,or you must force slower access with Sprite dot period and VRAM dot width ??

if someone know the truth ??, thanks in advance  :?

EDIT:ok i found it, it's psram for VRAM, http://console5.com/techwiki/images/3/37/LH5P832.pdf at 100/120ns access time .
And SRAM for scratch RAM, with a 100ns access time . http://console5.com/techwiki/images/c/c3/LC3564Q.pdf

What's the exact amount of bytes you can transfert in active display with the CPU ??

it seems that 65 bytes/scanline is false, because you have 455 cpu cyles /scanline, you lose 87 cpu cycles in hblank when the VDC fetches sprites's pattern, and you can only transfert 52 bytes per scanline .
« Last Edit: July 08, 2015, 10:32:45 AM by touko »