Tales of Phantasia using 3 27c160 posible?

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BokuNES
Posts: 11
Joined: Wed Apr 22, 2020 8:42 pm

Tales of Phantasia using 3 27c160 posible?

Post by BokuNES » Thu Apr 23, 2020 10:37 am

hi to all the community, this is my first post so here i go!, so i triying to make a tales of phantasia repro cart (for my personal use of course!) using a shvc-bj3m-01 board and 3 27c160 eproms, i make the connections, lift the mad-1 pin 4 and all but my problem comes here, i tried to use a 74ls139 (to control the /oe signal), but i dont know how to configure it!, someone know how to make this??, best regards and thanks!. (btw sorry for my bad english)

Markfrizb
Posts: 532
Joined: Sun Dec 02, 2012 8:17 am
Location: East Texas

Re: Tales of Phantasia using 3 27c160 posible?

Post by Markfrizb » Thu Apr 23, 2020 11:29 am

BokuNES wrote:
Thu Apr 23, 2020 10:37 am
hi to all the community, this is my first post so here i go!, so i triying to make a tales of phantasia repro cart (for my personal use of course!) using a shvc-bj3m-01 board and 3 27c160 eproms, i make the connections, lift the mad-1 pin 4 and all but my problem comes here, i tried to use a 74ls139 (to control the /oe signal), but i dont know how to configure it!, someone know how to make this??, best regards and thanks!. (btw sorry for my bad english)
I don't know where you would put 3 of those massive roms. A23 and A21 would be your signal choices. The BJ3M doesn't have an A23 trace so there's that....

BokuNES
Posts: 11
Joined: Wed Apr 22, 2020 8:42 pm

Re: Tales of Phantasia using 3 27c160 posible?

Post by BokuNES » Thu Apr 23, 2020 3:37 pm

Markfrizb wrote:
Thu Apr 23, 2020 11:29 am
BokuNES wrote:
Thu Apr 23, 2020 10:37 am
hi to all the community, this is my first post so here i go!, so i triying to make a tales of phantasia repro cart (for my personal use of course!) using a shvc-bj3m-01 board and 3 27c160 eproms, i make the connections, lift the mad-1 pin 4 and all but my problem comes here, i tried to use a 74ls139 (to control the /oe signal), but i dont know how to configure it!, someone know how to make this??, best regards and thanks!. (btw sorry for my bad english)
I don't know where you would put 3 of those massive roms. A23 and A21 would be your signal choices. The BJ3M doesn't have an A23 trace so there's that....
thanks for the reply :P, i will upload photos of the pcb, can you belive that it fits perfectly on a cartridge?? btw its that posible that you can make a schematic??, best regard and thanks again :P

Markfrizb
Posts: 532
Joined: Sun Dec 02, 2012 8:17 am
Location: East Texas

Re: Tales of Phantasia using 3 27c160 posible?

Post by Markfrizb » Thu Apr 23, 2020 4:03 pm

BokuNES wrote:
Thu Apr 23, 2020 3:37 pm
Markfrizb wrote:
Thu Apr 23, 2020 11:29 am
BokuNES wrote:
Thu Apr 23, 2020 10:37 am
hi to all the community, this is my first post so here i go!, so i triying to make a tales of phantasia repro cart (for my personal use of course!) using a shvc-bj3m-01 board and 3 27c160 eproms, i make the connections, lift the mad-1 pin 4 and all but my problem comes here, i tried to use a 74ls139 (to control the /oe signal), but i dont know how to configure it!, someone know how to make this??, best regards and thanks!. (btw sorry for my bad english)
I don't know where you would put 3 of those massive roms. A23 and A21 would be your signal choices. The BJ3M doesn't have an A23 trace so there's that....
thanks for the reply :P, i will upload photos of the pcb, can you belive that it fits perfectly on a cartridge?? btw its that posible that you can make a schematic??, best regard and thanks again :P
Think of A21 as (A20 upper and A20 lower). 32mb = 16mb upper + 16mb lower.....
So if the decoder has 2 control inputs A&B. if A21 is on control A (control B is grounded), then when A21 is low, it'll select output1, when A21 is high, it'll select the second output. Likewise, A23 is going to be A21 upper and A21 lower. 64mb = 32mb upper + 32mb lower. Tales of Phantasia is 48mb but still falls into the 64mb family when decoders are concerned.
to decode a 64mB rom into 16mb chunks ---4 x 16 = 64 --- is A23 High/Low + A21 High/Low. So one of the outputs won't be used.
Look at the '139 datasheet and read the function table....

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