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Feature #13

open

32x speed cpu without wait states

Added by foft almost 7 years ago. Updated almost 7 years ago.

Status:
New
Priority:
Normal
Assignee:
Start date:
04/08/2017
Due date:
% Done:

0%

Estimated time:

Description

The whole system is clocked at 32*original clock. However the 6502 turbo is limited to 16x due to the ram speed, since a block ram access cycle takes 2 cycles. Try to clock the block ram at 64* original clock as a quick win to get 32x turbo working.

Actions #1

Updated by foft almost 7 years ago

  • Subject changed from High speed cpu to 32x speed cpu without wait states
Actions #2

Updated by foft almost 7 years ago

  • Tracker changed from Bug to Feature
Actions #3

Updated by foft almost 7 years ago

  • Status changed from New to In Progress

Trying simply feeding in the clock at twice the speed to see if it passes timing!

Actions #4

Updated by foft almost 7 years ago

I have something working on the simulator - alone. Now need to plug it into the core proper to see if it works. Will probably need some clever timequest rules too, since the read/write deadlines are different now.

Actions #5

Updated by foft almost 7 years ago

Nope, this is not going to be so simple... Massive timing violations.

Actions #6

Updated by foft almost 7 years ago

So thinking about options...

Double the main clock speed and pipeline a bit
or
Output next address from antic and the cpu, so I can read the memory 1 cycle earlier - antic clearly knows what it will read, does the 6502 core?
or
Add a cache?!

Actions #7

Updated by foft almost 7 years ago

I enabled 32x mode in the core and sorted out single cycle writes from the block ram for now. Hardly any difference in sysinfo but good to see at least some difference.

Actions #8

Updated by foft almost 7 years ago

  • Assignee set to foft
Actions #9

Updated by foft almost 7 years ago

  • Status changed from In Progress to New
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