Old composite computer monitors, such as the AppleColor Composite Monitor IIe, often had a "vertical size" knob that could be turned down to make overscan visible. Beannaich from #nesdev wants to know who has an NES, a monitor like this, and a way to run test ROMs.
I have access to a couple different Amiga monitors like the 1080 and 1084 which I believe do have a vertical and horizontal size adjustments. As well as a PowerPak, and pretty much all common mapper carts hacked to accept EPROMs for testing.
I use my NES on a Commodore 1802 which has the knob you are talking about. It definitely does make the overscan are visible. (At least if I understand it correctly) Unfortunately I do not currently have the option to run test roms, sorry :C
Many later CRT televisions also have a service mode that you can enter where there will be a control for at least v- and h- position, and very often vsize too.
(This isn't entirely safe: sometimes settings are available that could cause the set to damage itself or become unuseable)
I have used the service menu of my TV to make it show all the visible image.
I've got the green monochrome Apple //c monitor, ROM testing ability, and a camera with good macro.
I have a composite IIe monitor and many nesssess? and eprom programmer.
I have a Famicom and a Sony PVM monitor that explicitly allows for viewing of this area.
I'm the one who you'd expect to have an Apple II or IIGS monitor around, but don't! Sad panda.
I'm fairly certain my Sony Wega TV's service/technician menu can do this, however. (I have the technicians manual in PDF so I can review it if you'd like)
Edit: Oh, and yes, I can run test ROMs. I have a top-loader NES, a front-loader NES (both NTSC), a PowerPak, and of course the USB-to-serial-to-controller-port method thanks to thefox.
Do you want a TV with 'v hold' and 'h hold' or are these different? I know a guy with lots of these; he's giving them away
But not an Apple II monitor. Sorry.
I think he already did whatever test he wanted. I tested it on my Apple //c monitor and reported back.
I'm so sorry to bump this but I picked up a apple ][e monitor today. Just so you know that I can help anyone in future (I also have a famicom everdrive).