STAG PP28 Programmer

[Bitstik]

Please go easy on me - I've searched a few threads for EEPROM and EPROM programmers and they seem a bit "spiky" for lack of a better expression - saying someting rude about someone's mother would elicit a less emotive response than referring to an Eprom as an EEPROM it seems

Whilst I was repaing my old issue 3 someone kindly burned me a few Eproms. As a result of this I bought a cheap TL866ii

Info on the web: https://mansfield-devine.com/speculatri ... bbc-micro/
Suggests Atmel AT28C256 EEPROM is a drop in replacement for a BBC Eprom. As it's a 32k chip I have to use the top 16k.
I've downloaded and unzipped some BBC Rom images

I've then copied the code to the top and bottom halves of the chip. The editor screen on windows shows the binary and the hex code to the right so info is getting to and from the chips despite me buying them off amazon and them arriving loose in a small box!

Plug into BBC (issue 3) and nothing is showing. This then led me to thinking perhaps I should get a "proper" old-school programmer.

I bought a Stag pp28 as I understood they could write BBC chips.

Well, it powers up but, on reading the manual I see that I need the "AM28" unit to program 27128 chips

Although the pins are the same the AM28 is needed to program the upper and lower parts of the chip as the PP28 seems to have a standard limit of 64k chips.

So here is my stupid question - is there something I can cobble together myself to program a 27128 chip and, if so, could a similar thing be made to program an AT28C256 EEPROM ?

How silly have I been?
Thanks
Andrew

[Bitstik]

Meant to say - Would something like a modded boo-bip EEPROM adaptor be of use?

I know I can buy one and use it straight from the BBC but that is too easy!

I'd like to make use of this vintage tech that I've got if possible

[KenLowe]

I can't comment on the Stag programmer as I've never owned one, but the TL866II is a nice little programmer and can program both EPROM and EEPROM. The only caveat is that it can't program older EPROMs (without modification) that need 21V to program.

If you're having issues, my guess is that you're not correctly loading the image correctly into the upper and lower areas of the chip. When loading the ROM image into the TL866II, firstly load with all the defaults to get the contents into the lower half of the Buffer. You then need to load it again to get it into the upper half of the Buffer. This time set the 'TO Buffer Strat [sic] Addr' to 4000 and set 'Clear Buffer when loading the file' to disabled. This will prevent overwriting what you loaded in the first step. You should now have two copies of the ROM in the Buffer over the range 0..7FFF. You can check this by scrolling through the Buffer window.

Once you've loaded the ROM into the buffer, it should just be a case of programming the IC (EPROM or EEPROM, depending what you've selected earlier).

Once programmed, you can then install the IC into one of the four sockets on the beeb mainboard. However, you should tie pin 1 to either 5v or 0v to prevent spurious switching between the upper and lower bank.

There's a bit of recent discussion on using a 28C256 in the beeb and the pin 1 issue here:

viewtopic.php?f=3&t=21071

[Bitstik]

Many thanks Ken- I've just come across that "pin1 issue" discussion and so will try that

[JasonStonier]

Meant to say - Would something like a modded boo-bip EEPROM adaptor be of use?

Yes, definitely. Once you have one you wonder how you ever managed without one.

I've got all my ROM images in 27C512 EPROMs in the BooBip adapters (4 ROM images per chip). For the price - one of the best upgrades you can get for the beeb in my opinion.

I have 2x of his 27C512 EPROM adapters, and 1x adapter that is 27C256 EEPROM + 32k Sideways Ram