HP48 hardware hacking -- SOIC EPROMS?

[Jonathan Busby]

I've been doing some HP48G/GX hardware hacking and I'm in need of a 32-pin SOIC EPROM. The problem is that all I can find are 32-PIN PDIP EPROMS or 32-lead PLCCs. I know I can use a daughterboard with an SMD PLCC chip but it would be a very tight fit and a real PITA. Does anyone know where to get 4Mbit x 8 32-pin EPROMS in SOIC packages, or are they no longer being produced?

Thanks,

Jonathan

[franco51]

Hi
I'm not sure they were ever available in the SOIP package. You may be able to find some TSOP or TSSOP devices but I'm guessing they are too wide / long?
BR
Frank

[Jonathan Busby]

(04-30-2019 11:31 AM)franco51 Wrote:  Hi
I'm not sure they were ever available in the SOIP package. You may be able to find some TSOP or TSSOP devices but I'm guessing they are too wide / long?
BR
Frank

Thanks for the reply I've looked at the available TS(S)OP packaged EPROMS, and, although some of them have the same dimensions as the SOIC equivalent, the 32-leads are not situated on the oblong sides of the package, but on he shorter top and bottom, which makes it incompatible with, say, replacing the 48 ROM.

It seems that Microchip Technology has the largest selection of ICs in which I'm interested and I might have some luck. There are some DIP to SMT adapters, but, I'm not sure if they're compatible dimension wise.

Thanks,

Jonathan

EDIT : I've checked several electronics distributors and it seems that 32-pin 4Mbit x 8 OTP EPROMS are only available from Microchip Technology in PLCC packages. See here : https://www.digikey.com/products/en/inte...ageSize=25

I guess an adapter or daughterboard is what's needed then. I've found some DIP to SOIC adapters, but they're not the right size and they only have 28 pins. I guess I'll have to use a daughterboard.

[blackjetrock]

(04-30-2019 03:18 PM)Jonathan Busby Wrote:  

(04-30-2019 11:31 AM)franco51 Wrote:  Hi
I'm not sure they were ever available in the SOIP package. You may be able to find some TSOP or TSSOP devices but I'm guessing they are too wide / long?
BR
Frank

Thanks for the reply I've looked at the available TS(S)OP packaged EPROMS, and, although some of them have the same dimensions as the SOIC equivalent, the 32-leads are not situated on the oblong sides of the package, but on he shorter top and bottom, which makes it incompatible with, say, replacing the 48 ROM.

It seems that Microchip Technology has the largest selection of ICs in which I'm interested and I might have some luck. There are some DIP to SMT adapters, but, I'm not sure if they're compatible dimension wise.

Thanks,

Jonathan

EDIT : I've checked several electronics distributors and it seems that 32-pin 4Mbit x 8 OTP EPROMS are only available from Microchip Technology in PLCC packages. See here : https://www.digikey.com/products/en/inte...ageSize=25

I guess an adapter or daughterboard is what's needed then. I've found some DIP to SOIC adapters, but they're not the right size and they only have 28 pins. I guess I'll have to use a daughterboard.

You might be able to find some of these obsolete ones, maybe:
https://www.digikey.co.uk/products/en/in...ageSize=25

Or, there are SPI flash chips that are in a 16 pin package. If you could find a suitable small FPGA you could create a parallel interface for the SPI flash chip.
Or, if you could find a suitable microcontroller in a SOIC32 and it was fast enough, you could maybe emulate a ROM?

Andrew

[Jonathan Busby]

(05-01-2019 07:32 AM)blackjetrock Wrote:  You might be able to find some of these obsolete ones, maybe:
https://www.digikey.co.uk/products/en/in...ageSize=25

Or, there are SPI flash chips that are in a 16 pin package. If you could find a suitable small FPGA you could create a parallel interface for the SPI flash chip.
Or, if you could find a suitable microcontroller in a SOIC32 and it was fast enough, you could maybe emulate a ROM?

Andrew

Thanks for the tip I hadn't considered using a small FPGA as I have several Xilinx FPGA dev boards and the FPGA chips aren't small enough, although, I bought those dev kits for CPU design which uses up a lot of resources ( A Digilent Arty using a Xilinx Artix-7 being my latest acquisition ). I guess if I could find a much smaller packaged FPGA I could use its distributed RAM as a "ROM". I'd have to include an SPI flash chip too though as the FPGA configuration data is volatile, which makes it kind of redundant. A better solution would be to use a very small 512KiB x 8 NAND flash chip. In terms of an MCU, I think I may be able to find one which is an SoC with a built-in FPGA and/or flash blocks. This would all still require the use of a daughterboard and the ICs would have to be quite small.

Regards,

Jonathan