On Oct 2, 20:38, Ram Meenakshisundaram wrote:
>
> [ Attachment (multipart/alternative): 2760 bytes ]
[please don't post multipart :-)]
> I hope that the firmware is downloaded to the chip each time it is fired
=
> up, but I am not sure. The chip is labelled as:
>
> TOSHIBA
> TC57H256D-70
> JAPAN 8906YAA
> VPP 12.5V
>
> Does anyone know what type of IC this is and where I can obtain one?
It's a standard 32768 x 8 CMOS EPROM, 70ns access time. I have the data
sheet if you really need it. Pinout is:
Vpp 1 28 Vdd
A12 2 27 A14
A7 3 26 A13
A6 4 25 A8
A5 5 24 A9
A4 6 23 A11
A3 7 22 ~OE
A2 8 21 A10
A1 9 20 ~CE
A0 10 19 D7
D0 11 18 D6
D1 12 17 D5
D2 13 16 D4
GND 14 15 D3
Like many devices of its time, it has an electronic signature, though it's
unlikely your circuit checks that. Anyway, the signature is obtained by
applying normal read voltage to all pins, except you apply 12V to A9. Then
with A0 at logic 1, you get the manufacturer code 0x98 and with A0=0 you
get device code 0x45.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
Received on Tue Oct 03 2000 - 02:39:49 BST