27c160 (42 pin) on a 40pin genesis PCB?

27c160 (42 pin) on a 40pin genesis PCB?
by nintendo2600 on 2012-02-24 (#90468)

Hello,

I was wondering if anyone could please let me know the proper way to wire a 27c160 (dip42) to a 40pin GENESIS PCB?
The game I plan on burning is pretty small and the only reason I'm using a 27c160 is it's the smallest 16bit chip I have
and I'm using a 40pin PCB as I got a bunch in a batch of genesis carts I bought to use as donors. I thought it would be as simple as pulling A19 and the extra VPP high but that has not worked for me so far. Hense why I'm asking for help

Also how do I know if a rom needs to be byteswapped or not (big edien VS small edien I believe the term is).

Thanks in advance for humoring my lack of Genesis Jitsu

by l_oliveira on 2012-02-24 (#90472)

The 27C160 is pin to pin compatible with the 40 pin MASKROM (JEDEC TYPE) used on MEGA DRIVE cartridges.

You just need to connect the two extra pins to their respective positions.

If you use a 16MBIT game, you just solder it straight as the MASKROM will be of 42 pin type.

If you notice the front of the board, pin B07 (A19) is all you need to connect to the eprom.

by nintendo2600 on 2012-02-24 (#90474)

l_oliveira wrote:
The 27C160 is pin to pin compatible with the 40 pin MASKROM (JEDEC TYPE) used on MEGA DRIVE cartridges.

You just need to connect the two extra pins to their respective positions.

If you use a 16MBIT game, you just solder it straight as the MASKROM will be of 42 pin type.

If you notice the front of the board, pin B07 (A19) is all you need to connect to the eprom.

But a 42 pin chip VS a 40 pin socket leaves 2 pins that don't have anywhere to go on the 40 pin socket so that is where I'm stuck.

by l_oliveira on 2012-02-24 (#90475)

nintendo2600 wrote:
But a 42 pin chip VS a 40 pin socket leaves 2 pins that don't have anywhere to go on the 40 pin socket so that is where I'm stuck.

Connect it so the two "extra pinst (1 and 42) are left out. (lift them)

by nintendo2600 on 2012-02-24 (#90477)

l_oliveira wrote:
nintendo2600 wrote:
But a 42 pin chip VS a 40 pin socket leaves 2 pins that don't have anywhere to go on the 40 pin socket so that is where I'm stuck.

Connect it so the two "extra pinst (1 and 42) are left out. (lift them)

So a19 and A18 just float?

by tokumaru on 2012-02-24 (#90478)

Unused address pins should usually be grounded, not left floating.

by l_oliveira on 2012-02-24 (#90479)

nintendo2600 wrote:
l_oliveira wrote:
nintendo2600 wrote:
But a 42 pin chip VS a 40 pin socket leaves 2 pins that don't have anywhere to go on the 40 pin socket so that is where I'm stuck.

Connect it so the two "extra pinst (1 and 42) are left out. (lift them)

So a19 and A18 just float?

If you only require 512KB of program space, do what tokumaru suggested. If you use the whole EPROM, connect both to their respective pins on the cartridge slot (B07 and B08)

by nintendo2600 on 2012-02-24 (#90481)

l_oliveira wrote:
nintendo2600 wrote:
l_oliveira wrote:
nintendo2600 wrote:
But a 42 pin chip VS a 40 pin socket leaves 2 pins that don't have anywhere to go on the 40 pin socket so that is where I'm stuck.

Connect it so the two "extra pinst (1 and 42) are left out. (lift them)

So a19 and A18 just float?

If you only require 512KB of program space, do what tokumaru suggested. If you use the whole EPROM, connect both to their respective pins on the cartridge slot (B07 and B08)

Ah ok I get you now! Thanks!

EDIT:

From this pinout it says A18 goes to B06 and A19 goes to B07 so is this pinout wrong and your advise correct? I can just try both but better that anyone who reads this in the future gets the correct information.

Code:
pin Name
A01 GND
A02 5v
A03 A08
A04 A11
A05 A07
A06 A12
A07 A06
A08 A13
A09 A05
A10 A14
A11 A04
A12 A15
A13 A03
A14 A16
A15 A02
A16 A17
A17 A01
A18 GND
A19 D07
A20 D00
A21 D08
A22 D06
A23 D01
A24 D09
A25 D05
A26 D02
A27 D10
A28 D04
A29 D03
A30 D11
A31 5v
A32 GND
pin Name
B01 ?
B02 !HRST
B03 ?
B04 A09
B05 A10
B06 A18
B07 A19
B08 A20
B09 A21
B10 A22
B11 A23
B12 Video
B13 Vsync
B14 HSync
B15 HS_CLK
B16 !C_OE
B17 !C_CE
B18 !AS
B19 CLK
B20 !DTACK
B21 ?
B22 D15
B23 D14
B24 D13
B25 D12
B26 !LO_MEM
B27 !RST
B28 !LDS
B29 !UDSW
B30 !S_RST
B31 ?
B32 !C_DTCT

by l_oliveira on 2012-02-24 (#90484)

The pinout is right. I might have overlooked it. The addresses are laid out from left to right on the connector. Sorry about any mistakes on the previous advice.

by sdm on 2012-03-12 (#91277)

long time ago i uses many times 27C160 and 27C322 eproms on Sega Genesis eprom-cartridge without any problems.