exxos's Atari, Amiga & retro forum

In terms of ROM there are devices like the ST39LF801 which is 8Mbit x 16, would be ideal, but it is 3.3V so I would need level translators to use this..

There is also 5V flash SST39SF040 but 4Mbit x 8bit, so will need 2 of these.. Which I think will be easier and take less board space than adding in level translators.. But of course only enough space for 2 flash banks, not 4. But the least initially the 5V ones will be plenty get things working and tested.

Looking at SRAM, there are 5V and 3.3V of thing likes this
IS61WV5128BLL-10TLI
IS61C5128AL-10TLI

https://www.mouser.co.uk/ProductDetail/ ... A0dXGpI%3d

So either way is possible, but initially to avoid using level translators, 5V makes easy work for a prototype. Again would need two of these chips for 4Mbit. So only going to give 1MB of fast-ram, but again, this is a prototype testing so does not really matter on size. Of course this will be large enough to try ROM to SRAM copy as I was discussing earlier..

I will try and start designing new PCB for this soon....

exxos wrote: ↑Fri Jun 01, 2018 7:47 pm 58MHz!!!
int-div from 566%(55mhz) to just shy of 600%!

Holy crap.... You really did it

IngoQ wrote: ↑Mon Jun 04, 2018 1:33 pm Holy crap.... You really did it

Started the schematic and rough pcb layout...

There has to be a "cut out" on the top left of the booster board (like the V2.2 booster) to avoid "hitting" the MMU.. The Flash and Fast-Ram take up a lot of space.. so god knows how more fast-ram is going to physically fit on later boards.

Looks good, can you piggy back a ram expansion board on perhaps?

IMHO it's more attractive on the STFM to overclock the MMU. While not as fast as running it directly off the CPU, it's proper ST RAM and it's an "easy" 200% boost.

FAST ROM, sure.

Forgottenmyname wrote: ↑Wed Jun 06, 2018 9:39 am Looks good, can you piggy back a ram expansion board on perhaps?

Possible it might have to be done like that.

troed wrote: ↑Wed Jun 06, 2018 9:45 am IMHO it's more attractive on the STFM to overclock the MMU. While not as fast as running it directly off the CPU, it's proper ST RAM and it's an "easy" 200% boost.

FAST ROM, sure.

But its not easy because its not stable and with all the mods like new RAM etc, most people won't be able to do it. I even got loads of SMT MMU's to do just that, but as you know, I want to move to FPGA MMU and clock it at the same speed as the CPU and include SRAM on board. Though as this will take the next year to do.. it will have to wait.

Meanwhile, the V2.2 booster has been out of stock for some time, so I really need to wrap up this booster as its successor. Fast-Ram will run over 6x faster along with ROM and the CPU.

exxos wrote: ↑Wed Jun 06, 2018 10:07 am Meanwhile, the V2.2 booster has been out of stock for some time, so I really need to wrap up this booster as its successor. Fast-Ram will run over 6x faster along with ROM and the CPU.

Maybe I'm misunderstanding, but adding alt-ram will require TOS 2.06 and it won't be of use for anything that doesn't support alt-ram. Or do you only intend it for shadowing TOS?

troed wrote: ↑Wed Jun 06, 2018 12:45 pm Maybe I'm misunderstanding, but adding alt-ram will require TOS 2.06 and it won't be of use for anything that doesn't support alt-ram. Or do you only intend it for shadowing TOS?

TOS206 is needed for alt-ram, not a problem for the booster. I have no idea what use alt-ram is, but people keep nagging about it, people buy monster for alt-ram and IDE, so its half step there for now.

Problem is 10ns fast-ram is likely going to be expensive, doable for 1MB, but cost and size soon ramps up with more MB. So I may look to using 10ns sram for ROM shadow, and maybe go with 55ns for 8MB fast-ram, but limits to around 32Mhz effective speeds then.

Once I get this booster done, it can go on sale, get a few sales to fund looking into the FPGA blitter and IDE next likely.

I have been looking at options for flash and ROM...

Basically 55ns 8Mb 3.3V is the only real option for the "fast ram" bank. 3.3V flash 8Mb 55ns. 2Mb 3.3V 10ns for the ROM shadow. It's the smallest and cheapest set of SRAM options. Problem is a huge bank of IO converters.. plus I have space limitations so keeping the SRAM & Flash to 1 IC is the only real option because of space limitations. I am hoping to put all the IO converts in a huge row, then branch off to the "3.3V section" above the IO row.

Routing this thing will be a nightmare and likely be a while before anymore updates for a while I do the PCB layout.