[Simh] DEC VT emulators on MAME

[Tim Stark]

I took a look on your pictures.  That is 32Kx8 27C256 EPROM chips.  Total 160K ROM space.

Use 27C256 EPROM programmer and connected to that ROM cartridge to access data inside chips.  Read Jason's message.

I do not have tools at this time.

Tim

-----Original Message-----
From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Armistead, Jason
Sent: Tuesday, April 18, 2017 9:54 AM
To: simh at trailing-edge.com
Subject: Re: [Simh] DEC VT emulators on MAME

Malcolm

After looking at the photos you took of the ROM cartridge internals I think you might be better leaving them in-place and making up an adapter from the edge connector to a 28 pin socket that you could plug into an EPROM programmer.  By the looks of it, there's no chip selection/data buffering logic on the PCB, and it's just the EPROMs and some decoupling capacitors.  If you activate the appropriate chip select and output enable lines of the EPROMS one at a time, you can make sure just a single chip is talking to the EPROM programmer and the rest would be dormant.  The pinouts of the 27C256 chips should be readily available.

Good luck !

Jason

-----Original Message-----
From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of malcolm at avitech.com.au
Sent: Tuesday, 18 April 2017 9:25 AM
To: simh at trailing-edge.com
Subject: Re: [Simh] DEC VT emulators on MAME

Just a quick update: I've broken open the VT340 ROM cartridge.  Inside are 5 x surface-mount N27C256 ROMs.

Some pictures of the ROM cartridge are now included on this page -> http://avitech.com.au/?p=1818

Is there anyone who has the tools, time and interest to remove these ROMs and dump the contents?  If so, please let me know and I will pay the cost of shipping to get this cartridge to you.

Malcolm.

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