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

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nintendo2600
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27c160 (42 pin) on a 40pin genesis PCB?

Post by nintendo2600 »

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
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l_oliveira
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Post by l_oliveira »

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.
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nintendo2600
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Post by nintendo2600 »

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.

Image
Last edited by nintendo2600 on Fri Feb 24, 2012 4:46 pm, edited 1 time in total.
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l_oliveira
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Post by l_oliveira »

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) 8)
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nintendo2600
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Post by nintendo2600 »

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) 8)
So a19 and A18 just float?
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tokumaru
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Post by tokumaru »

Unused address pins should usually be grounded, not left floating.
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l_oliveira
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Post by l_oliveira »

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) 8)
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)
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nintendo2600
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Post by nintendo2600 »

l_oliveira wrote:
nintendo2600 wrote:
l_oliveira wrote: Connect it so the two "extra pinst (1 and 42) are left out. (lift them) 8)
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: Select all

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 
 
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l_oliveira
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Post by l_oliveira »

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.
sdm
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Post by sdm »

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