Programming a TBP28L22N PROM

[Amraduk]

I have an old TBP28L22N PROM that I need copying and programmed into a new TBP28L22N PROM. Does anyone have the means to do this? I can supply the data sheet for it if needed. Thanks.

Regards,

Dave.

[SiriusHardware]

Is this a Texas Instruments device? The supported devices list for my ALL07A programmer includes a Texas instruments 28L22, which is a 20-pin, 256 * 8 bit Bipolar PROM. I think the 'N' suffix on your device probably just means it's a DIP packaged device.

Wait a couple of days and see if anyone just around the corner from you offers to help - thus negating the need to risk your original device in the post.

Otherwise, PM me and I'll be happy to do it for you. I take it this is for a synthesised PMR radio of some sort?

[Amraduk]

@Sirius,

Thanks for your reply

Originally Posted by SiriusHardware

Is this a Texas Instruments device?

Yes, it is.

The supported devices list for my ALL07A programmer includes a Texas instruments 28L22, which is a 20-pin, 256 * 8 bit Bipolar PROM. I think the 'N' suffix on your device probably just means it's a DIP packaged device.

That's the one, yes, the 'N' does mean a plastic DIP package.

Otherwise, PM me and I'll be happy to do it for you.

Many thanks. I suspect I will be taking you up your offer!

I take it this is for a synthesised PMR radio of some sort?

No, it's for an electronic test card. It was published in 1981 in the BATC's Amateur Television Handbook and was designed by Richard Russell (BBC- retired). I bought the PCBs and Prom for it at the time but never got around to building it. It consists of three PCBs and I bought 1 2/3 sets and one PROM, the 2/3 set is missing board three but it wouldn't be very difficult to make a copy. If I'm going to make two, I'll need another PROM, hence my request.

The PROM contains data for one quadrant of a circle, the other three quadrants use the same data which is manipulated so it goes in the right places!

I asked Richard if he still had the capability to program a PROM but, unfortunately, he doesn't.

Regards,

Dave.

[SiriusHardware]

Thanks for the info - when / if you want to go forward with it just PM me and we'll take it from there.

...It's not entirely clear from your last post whether you do actually have a second, empty PROM. Your first post seemed to suggest that you did - I don't, I only have the programmer capable of reading and programming them but not, alas, any PROMs.

If PROMS are a problem I could still read the code out of the PROM for you and programme it into a small EPROM (2716)? for which you could make an adaptor / converter / daughterboard which you could plug into the PROM socket of your second unit. It's a trick often used in ex-PMR radios which originally used Bipolar PROMS. That, plus your 'handle' was what led me to guess (incorrectly) that this was for a radio.

[Amraduk]

Originally Posted by SiriusHardware

Thanks for the info - when / if you want to go forward with it just PM me and we'll take it from there.

Thanks, there are no 'ifs' about it, I do definitely want the PROM programming!

It's not entirely clear from your last post whether you do actually have a second, empty PROM.

I'm sorry if I didn't make it clear, I don't have a second PROM at the moment but I have a couple on order which should arrive soon - I hope!

Your first post seemed to suggest that you did - I don't, I only have the programmer capable of reading and programming them but not, alas, any PROMs.

I wouldn't dream of expecting you to supply the PROM, and I'm sorry if I gave you that impression.

If PROMS are a problem I could still read the code out of the PROM for you and programme it into a small EPROM (2716)? for which you could make an adaptor / converter / daughterboard which you could plug into the PROM socket of your second unit. It's a trick often used in ex-PMR radios which originally used Bipolar PROMS.

An EPROM would be quite unsuitable because it would be far too slow for use in video applications. The PROM has an access time of about 45nS, whereas EPROMs have access times of a couple of hundred nS or so. Thanks for the offer, though.

That, plus your 'handle' was what led me to guess (incorrectly) that this was for a radio.

Well, that's not an unreasonable assumption! I chose that user name because I'm a licensed radio amateur, my callsign is G8TVW. I'll contact you again once the PROMs have arrived. Thanks again.

Regards,

Dave.

[julie_m]

Originally Posted by Amraduk

An EPROM would be quite unsuitable because it would be far too slow for use in video applications. The PROM has an access time of about 45nS, whereas EPROMs have access times of a couple of hundred nS or so. Thanks for the offer, though.

If you need faster access time than one chip can manage, why not use a bit-slicing technique? Stack up eight EPROMs, connect your bottom three address lines to a 74HC138 and use the outputs to drive the enable inputs of the 8 EPROMs. So you are effectively accessing eight bytes in one read cycle.

[Amraduk]

Hello Julie,

Originally Posted by julie_m

If you need faster access time than one chip can manage, why not use a bit-slicing technique? Stack up eight EPROMs, connect your bottom three address lines to a 74HC138 and use the outputs to drive the enable inputs of the 8 EPROMs. So you are effectively accessing eight bytes in one read cycle.

Thanks for your suggestion. As I will be getting the TBP28L22 PROM, that removes the need to do so.

Regards,

Dave.

[SiriusHardware]

Originally Posted by Amraduk

I wouldn't dream of expecting you to supply the PROM, and I'm sorry if I gave you that impression.

If I had happened to have one, I would have been glad to let you have it so it could at last be doing the job it was born to do instead of sitting in my cupboard.

I see your point about PROM vs. EPROM speed - I hadn't considered that.

I'll await your PM when you have the PROMs.