17 Dec
2001
17 Dec
'01
11:27 a.m.
On Sun, 16 Dec 2001, Ben Franchuk wrote:
ajp166 wrote:
I guess you are not using Xilinx, but one thing I've noticed lately is the
appearance of large, serial flash EEPROMs. We are using one on them in a
new Xilinx design. The SST part is a 1 Mb chip (128KBytes) 8 pin SOP
package = $1.35. So instead of Xilinx's $4.40 OTP chip we use a 8 pin PIC
and the serial EEPROM for a total of $2.29 and get re-programmability...
A newer chip that can still be found is the WD37C65
that will do 125ns easily. Or you could easily find a d765
off an old board or NOS from JDR.
The floppy disk chips have arrived in the post friday. I hope to get
a chance to pick them monday.I will keep the WD37C65 in mind but
"A bird in the hand is worth two in the bush.". I have added wait
states internally for I/O.
Allison
I've built enough to enjoy later parts as
I'm old enough to want
it done in a lifetime and the older parts meant tons more support
parts and the requisite connections. Of the latter, the fewer the
better for both buildability and reliability.
Well I managed to stick my serial uart in the FPGA. One good feature
of 'dumb' hardware is that they can be used for bootstrapping the cpu.
(Mind you you still need a rather big prom to boot the FPGA but that
is another story) --
Ben Franchuk --- Pre-historic Cpu's --
www.jetnet.ab.ca/users/bfranchuk/index.html
Peter Wallace
Mesa Electronics