Off Topic - 2708 eProm

[Elia Mady]

Hi guys,

This is a bit off topic but seeing how much knowledge this group has I thought to ask. I am doing a side project that requires a 2708 eprom. I do have one but my programmer will only do 2716 upwards. How can I programmer it or replace it with a 2716, any ideas?

For the curious, I am building the Elektor Junior Computer with a 6502 processor.

Thanks,
Elia

[Peter Fielden-Weston]

Elia,

What programmer are you using and what is the full number of the IC?

Peter

[Elia Mady]

Hi Peter,

I am using a programmer I got off eBay, the G. The chip  is MCM2708C. Thanks for helping out.

Elia

[Peter Willard]

While the 2708 Eprom was state of the art "once long ago", its need for +5V  -5V and +12V eventually made it an oddball and finding a prpgrammer that supports it will be a chore unless you own or have access to a VERY EXPENSIVE programmer from the 70's and 80's.

 Think of the 2716 as as being 2 Stacked  2708's.  You could leave off the top Address pin on the 2716 (tied LOW) and it would behave like a 2708 with 1/2 trhe chip going unused.

[Peter Willard]

Handy Chart:

[Thomas Riesen]

Hi Elia

What type of programmer did you bought?

Thomas

[Elia Mady]

I bought this one:

http://m.ebay.co.uk/itm/Pro-USB-G540-Universal-Bios-GAL-Programmer-EPROM-FLASH-51-AVR-PIC-MCU-SPI-B0206-/261361720423?epid=1791697093&hash=item3cda5f5c67%3Ag%3AKPYAAOxyRhBSvH0j&_trkparms=pageci%253A5c4a0887-7d2f-11e7-8263-74dbd1809fe2%257Cparentrq%253Ac83985c015d0a9c9b8c5eecbffffb022%257Ciid%253A13

[Elia Mady]

So if I use the 2716 as you explained Peter, how easy is it to programmer with the 2708 image?

Elia

[Peter Fielden-Weston]

Hi All,

During a little research I found that the book "Build Your Own Z80" has three circuit diagrams for 2708 programmers. It is currently available on t' interwebbies.

Peter

[Daniel Quadros]

It is fairly trivial: first fill the first 2K (0x0000 to 0x7FF) in the memory of the programmer with 0xFF, then load the image starting at 0x00 and then program the EProm.

Daniel

[Jan S]

Elia,

There are other issues regarding 2708/2508. I suggest You stick to 2716 :-)

/Jan

[Elia Mady]

Thank you all for the replies and suggestions. I have ordered some 2716's and will have a go at it.

Elia