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Neglected PET needing some love

daver2 said:
There is no trick to writing the PETTESTER ROM at all.

Are you using the BIN or HEX file to download to the programmer? The BIN file should be exactly 2K Bytes (2048 bytes) in size.

What is your programmer and how do you know it is not programming correctly?

The usual "hit & miss" could be how you are actually programming the device itself (or more correctly, transferring the file down to the programmer).

Perhaps you could post the process you are using?

It would be way more useful to concentrate on getting this running. It is the only way to truly test the RAM - and makes testing the keyboard much easier.

Got to go and do some chores...

Dave
Click to expand...

My programmer is a TL866II-Plus
The eproms are M2716

First I put the eprom in the programmer and clicked "blank check", that checks out fine. Then I load up the .bin file and click "Program". This brings up this window:
1665842255642.png

I don't change anything I just click "program". The first time it failed right away. The 2nd time it didn't fail on the write but it failed on the verify.
 
I was able to erase the chips that I had failures on and tried again, same result as the 2nd time. It wrote fine but failed to verify:
1665843350870.png
 
M2716 need a programming voltage (VPP) of 25V, which the tl866ii-plus can't do. If I remember correctly it goes up to 18V.

You need a pin compatible EPROM which can be programmed with lower voltages, another programmer or you feed the 25V in externally (e.g. While bending the vpp pin out). But that is risky and requires timing.
 
Yep, exactly what I said back in post #157 and is stated in the manual:

1665843724017.png

A different EPROM programmer or EPROM device is called for I am afraid.

Dave
 
I would simply buy the economic GQ-4x programmer on ebay which can also program a host of other IC's like the 2716 including the TMS2532JL, useful for the PET. You will use it a lot and it will pay for itself in short order.
 
Or, you could try 27C32 EPROMs and program the code into the top half of those - the reason to choose those specifically is that they typically have a lower VPP (required programming voltage) of just 12.5V, well within the 'range' of your programmer.

A standard 2732 can usually be used to substitute for a 2716 in the same way, by programming the code into the upper half of the device but they require the same 'difficult' 25V VPP as the 2716. The 2732A typically has a VPP of 21V and -may- manage to program with the max 18V that the TL8xxx can manage.

Safer bet would be to use 27C32 EPROMs, as long as they are in the device support list of your programmer of course.

You could probably also use 28C16 EEPROMs as well, but I don't have the pinout for those to hand so I'm not absolutely certain about that. (Crossed with dave_m)
 
hmm well let's see the GQ-4x programmer is a bit more than I was looking to spend right now but I might opt for that anyway if it looks like my cheapo eprom programmer won't be of much help to me on this project (or future projects)

When I go searching for 2816's or 27c32's I don't see anything from reputable retailers (initially it looks like there are matches but if you click on it it's a completely different chip). Sure, there are lots of used ones on eBay, but that's kind of sketchy because you never know what condition those chips are in, if they're not blank (and maybe I can't erase them) so I'd rather have new, blank, chips from digikey or mouser or something but I'm not seeing those chips on those sites.
 
There were some amazingly good 2716 NOS eproms on ebay , but they have all been snapped up but one:

www.ebay.com

MHB2716C TESLA GOLD-PLATED 2716 EPROM - Military grade quality | eBay

MHB2716C TESLA GOLD-PLATED EPROM. This has given the highest possible quality to the product. Temperature range: -55°C - 150°C. You may be also interested in a similar chipMHB8708C.
www.ebay.com

I agree it is better to get new ones that have not been programmed. These look pretty good:

www.ebay.com

SGS M2716 F1 Programmable E-Prom New Quantity of (2) From Static Tube | eBay

SGS M2716 F1 Programmable E-Prom New Quantity of (2) From Static Tube.
www.ebay.com

There are many out there with a really tiny dies from the far east. I think its better to go for new very old stock myself.

Just looking around, if I needed more 2716's I would buy these, ACsurplus are good sellers and this vintage stock looks excellent to me, you can't go wrong with these (and the GQ-4x) I would suggest:

www.ebay.com

QTY-1 TMS2716JL-45 TI EPROM 2Kx8 Ceramic DIP VINTAGE OLD STYLE PKG RARE | eBay

Rare part we only have limited quantity. this is for 1 piece. NOS AS PER PHOTO.
www.ebay.com
 
daver2 said:
Yes they do. Ignore the 2716...

Dave
Click to expand...
okay found two 2816's for sale on ebay from someone only about 30 min away so shouldn't take long to get here $15 for the pair. They're EEPROMS as opposed to UV erasable though. So far I haven't tried to erase a prom with my programmer but they are listed as new old stock so assuming they program correctly I won't need to even try to erase.
 
Wow, you are right. 2816's are getting hard to find. If you have trouble programming the ebay parts, I will send you a programmed part. It is important that you test with daver's PETTESTE2KV04 program as it will help fix the PET.
-dave_m
 
Divarin said:
I thought the 2716's need the higher voltage? I was looking for 2816's or 27C32's.
Click to expand...
Yes they do but its pretty standard and supported by the GQ-4x. Similar higher voltages, than what your current programmer supports are also used for ICs like the TMS2532JL that are also useful for the PET. The 2716's are much more economical and easy to find than lower voltage eprom variants. So rather than trying to use a rarer & more expensive IC's to suit the lack of ability of your programmer, you should get the GQ-4x to be able to program more plentiful and readily available eproms like the 2716. The initial outlay for the GQ-4x will pay for itself in the time and costs it saves you later.
 
Btw, it looks like there's a successor to the TL866II-Plus, the T48, which can program 25V VPP EEPROMs according to the website: http://www.xgecu.com/en/

It would be interesting to know how it compares to the GQ-4x...
 
powerlot said:
Btw, it looks like there's a successor to the TL866II-Plus, the T48, which can program 25V VPP EEPROMs according to the website: http://www.xgecu.com/en/

It would be interesting to know how it compares to the GQ-4x...
Click to expand...
If i didn't already own the older model GQ-4x since 2010, I'd be tempted, On paper they seem to outshine the GQ-4x and newer GQ-4x4 in as much they support PAL/GAL and some TTL testing and a bit cheaper.
 
I also have the massive vintage BP1400 universal device programmer which interfaces to the computer on the parallel port. I was lucky to find one that was basically new with the original manual and driver disk. It supports many vintage devices.

One interesting thing about the GQ-4x (I was the one who found this out), if it is set to program or read the Dallas BBSRAM type DS1225, on those settings it will read & program the FM16W08 FRAM. The Dallas IC's are used in the famous Tek scope the 2465B. I moved to FRAMs in my three 2465B's, to avoid the battery going flat issue in the Dallas RAMS. I notified the makers of the GQ-4x and they added the FRAM to the supported devices list.
 
I also own a few older programmers, Serial and Parallel port, Data I/O, Needham, I like my GQ-4x but if it died tomorrow i probably wouldn't buy another considering the other options out there.
 
Malc said:
I also own a few older programmers, Serial and Parallel port, Data I/O, Needham, I like my GQ-4x but if it died tomorrow i probably wouldn't buy another considering the other options out there.
Click to expand...
Though, given that the GQ-4x's are only around the $100 mark, the build quality is reasonable too, they seem to have good proportions for function, quality and economy. And at least they are well supported by the manufacturer, with a good number of devices. So they are sort of middle of the road I guess, not too expensive, not too cheap and nasty. Mine has never given me any trouble. The software appears glitch free.
 
Although the T48 does look interesting and does allegedly support the 2716, I can't see any mention of the Hitachi or Texas 2532 EPROMs in its device support list - these are the ones which are most useful for replacing failed PROMs in PETs, so it is a great pity the T48 does not support them.

assuming they program correctly I won't need to even try to erase.
Click to expand...

If you try to program EEPROM devices which are already programmed you will probably get a 'device is programmed, do you want to patch?' message as you would if you tried to program an EPROM which wasn't blank. However, when you have the 28(C)16 device selected you will find there is an additional 'Erase' action available which you don't normally get when the selected device is an EPROM. Just use that to clear the 28(C)16 first, then programme it.
 
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